Edificio EXPO cInca Garcilaso sn E-41092 Sevilla - Spain Telephone direct line (+34-95) 4488-284 switchboard 4488-318 Fax 4488-426 Internet httpeippcbjrces Email jrc-ipts-eippcbceceuint

EUROPEAN COMMISSION DIRECTORATE-GENERAL JRC JOINT RESEARCH CENTRE Institute for Prospective Technological Studies Sustainability in Industry Energy and Transport European IPPC Bureau

Integrated Pollution Prevention and Control

Draft Reference Document on

Energy Efficiency Techniques Draft April 2006

Measure energy consumptionand production

Review performanceand action plan

Implement energysaving measure

Develop targets

Produce reports to monitor energy use

against output

This document is one of a series of foreseen documents as below (at the time of writing not all documents have been drafted)

Reference Documents on Best Available Techniques Code Large Combustion Plants LCP Mineral Oil and Gas Refineries REF Production of Iron and Steel IampS Ferrous Metals Processing Industry FMP

Non Ferrous Metals Industries NFM Smitheries and Foundries Industry SF Surface Treatment of Metals and Plastics STM Cement and Lime Manufacturing Industries CL Glass Manufacturing Industry GLS Ceramic Manufacturing Industry CER

Large Volume Organic Chemical Industry LVOC Manufacture of Organic Fine Chemicals OFC Production of Polymers POL Chlor ndash Alkali Manufacturing Industry CAK Large Volume Inorganic Chemicals - Ammonia Acids and Fertilisers Industries LVIC-AAF Large Volume Inorganic Chemicals - Solid and Others industry LVIC-S

Production of Speciality Inorganic Chemicals SIC Common Waste Water and Waste Gas TreatmentManagement Systems in the Chemical Sector CWW Waste Treatments Industries WT Waste Incineration WI Management of Tailings and Waste-Rock in Mining Activities MTWR Pulp and Paper Industry PP

Textiles Industry TXT Tanning of Hides and Skins TAN

Slaughterhouses and Animals By-products Industries SA

Food Drink and Milk Industries FDM Intensive Rearing of Poultry and Pigs ILF Surface Treatment Using Organic Solvents STS

Industrial Cooling Systems CV Emissions from Storage ESB

Reference Documents

General Principles of Monitoring MON Economics and Cross-Media Effects ECM

Energy Efficiency Techniques ENE

Executive Summary

SSEIPPCBENE_Draft_1 Version April 2006 i

EXECUTIVE SUMMARY

To be written upon completion of the whole document

Preface

SSEIPPCBENE_Draft_1 Version April 2006 iii

PREFACE

1 Status of this document Unless otherwise stated references to lsquothe Directiversquo in this document means the Council Directive 9661EC as amended by Directive 200387EC on integrated pollution prevention and control As the Directive applies without prejudice to Community provisions on health and safety at the workplace or any energy efficiency provisions so does this document This document is a working draft of the European IPPC Bureau It is not an official publication of the European Communities and does not necessarily reflect the position of the European Commission

2 The mandate of the work The mandate for this document is threefold a) to implement a special request from the Commission Communication on the

implementation of the European Climate Change Programme (COM(2001)580 final) ECCP concerning energy efficiency in industrial installations The ECCP asks that effective implementation of the energy efficiency provisions of the IPPC Directive are promoted and that a special horizontal BREF addressing generic energy efficiency techniques is prepared

b) gives general guidance to operators and regulators on how to approach and implement

energy efficiency requirements set out in the IPPC Directive and c) be one of several measures foreseen in the European Climate Change Programme aimed at

reducing the emissions of greenhouse gases This document on energy efficiency has links to other Commission instruments eg the following actions have an interface with this document bull Green Paper on Energy Efficiency COM(2005)265 final of 22 June 2005 bull Directive on greenhouse gas emission trading (200387EC) bull Directive on the promotion of cogeneration (20048EC) bull Directive on the energy performance of buildings (200291EC) bull proposal on energy end-use energy efficiency and energy services COM(2003)739 bull the framework Directive for the setting of eco-design requirements for energy using

products EuP (200532EC) bull an Energy Efficiency Toolkit for SMEs developed in the framework of the EMAS

Regulation bull several studies and projects under the umbrella Intelligent Energy ndash Europe and SAVE

which deal with energy efficiency in buildings and industry

3 Relevant legal obligations of the IPPC Directive and the definition of BAT In order to help the reader understand the legal context in which this document has been drafted some of the most relevant provisions of the IPPC Directive including the definition of the term lsquobest available techniquesrsquo are described in this preface This description is inevitably incomplete and is given for information only It has no legal value and does not in any way alter or prejudice the actual provisions of the Directive

Preface

iv Version April 2006 SSEIPPCBENE_Draft_1

The purpose of the Directive is to achieve integrated prevention and control of pollution arising from the activities listed in its Annex I leading to a high level of protection of the environment as a whole including energy efficiency The legal basis of the Directive relates to environmental protection Its implementation should also take account of other Community objectives such as the competitiveness of the Communityrsquos industry thereby contributing to sustainable development More specifically it provides for a permitting system for certain categories of industrial installations requiring both operators and regulators to take an integrated overall look at the polluting and consuming potential of the installation The overall aim of such an integrated approach must be to improve the management and control of industrial processes so as to ensure a high level of protection for the environment as a whole Central to this approach is the general principle given in Article 3 that operators should take all appropriate preventative measures against pollution in particular through the application of best available techniques enabling them to improve their environmental performance including energy efficiency Competent authorities responsible for issuing permits are required to take account of the general principles set out in Article 3 when determining the conditions of the permit These conditions must include emission limit values supplemented or replaced where appropriate by equivalent parameters or technical measures According to Article 9(4) of the Directive these emission limit values equivalent parameters and technical measures must without prejudice to compliance with environmental quality standards be based on the best available techniques without prescribing the use of any technique or specific technology but taking into account the technical characteristics of the installation concerned its geographical location and the local environmental conditions In all circumstances the conditions of the permit must include provisions on the minimisation of long-distance or transboundary pollution and must ensure a high level of protection for the environment as a whole Member States have the obligation according to Article 11 of the Directive to ensure that competent authorities follow or are informed of developments in best available techniques

4 The IPPC Directive and energy efficiency Energy efficiency is not restricted to any one industry sector mentioned in Annex 1 to the Directive as such but is a horizontal issue which is required to be taken into account in all cases In the Directive there are indirect and direct references in energy efficiency in the following articles which will then be explained bull 211 definition of BAT indirect reference bull Annex IV considerations included in BAT direct reference This Directive requires that permits must contain conditions based on Best Available Techniques (BAT) as defined in Article 211 of the Directive to achieve a high level of protection of the environment as a whole A high level of protection means that in issuing the installations permits the regulators have to consider all environmental effects caused by the installation including the effects of energy use Article 211 of the Directive specifies BAT in the following way lsquoBestrsquo shall mean most effective in achieving a high general level of protection of the environment as a whole lsquoAvailablersquo techniques shall mean those developed on a scale which allows implementation in the relevant industrial sector under economically and technically viable conditions taking into consideration the costs and advantages whether or not the techniques are used or produced inside the Member State in question as long as they are reasonably accessible to the operator

Preface

SSEIPPCBENE_Draft_1 Version April 2006 v

lsquoTechniquesrsquo shall include both the technology used and the way in which the installation is designed built maintained operated and decommissioned Furthermore Annex IV specifies what considerations must be taken into account generally or in specific cases when determining best available techniques as defined in Article 2 (11) bearing in mind the likely costs and benefits of a measure and the principles of precaution and prevention The references to energy efficiency in the IPPC Directive are a) Annex IV One of the issues to be taken into account is the consumption and nature of raw

materials (including water) used in the process and their energy efficiency (item 9)b) Article 3 (d) direct reference The Directive requires that Member States shall take the

necessary measures to provide that the competent authorities ensure that installations are operated in such a way that among other things energy is used efficiently (Article 3 (d))

c) Article 61 direct reference In Article 6 it is said that Member States shall take the necessary measures to ensure that an application to the competent authority for a permit includes a description of the raw and auxiliary materials other substances and the energy used in or generated by the installation

d) Article 91 indirect reference In Article 91 concerning conditions of the permit it is stipulated that Member States shall ensure that the permit includes all measures necessary for compliance with the requirements of Articles 3 and 10

e) Article 93 direct reference (amendment) In Article 93 (amendments by Directive 200387EC) concerning limit values it is stipulated that IPPC-permit shall not include an emission value for direct emissions of that gas meaning greenhouse gases specified in Annex 1 to Directive 872003

Furthermore it is stipulated that for activities listed in Annex 1 to Directive 200387EC Member States may choose not to impose requirements relating to energy efficiency in respect of combustion units or other units emitting carbon dioxide on the site Directive 200387EC covers some but not all activities covered by the IPPC Directive This document gives general advice how to implement those requirements

5 Objective of this document Article 16(2) of the Directive requires the Commission to organise lsquoan exchange of information between Member States and the industries concerned on best available techniques associated monitoring and developments in themrsquo and to publish the results of the exchange

The purpose of the information exchange is given in recital 25 of the Directive which states that lsquothe development and exchange of information at Community level about best available techniques will help to redress the technological imbalances in the Community will promote the worldwide dissemination of limit values and techniques used in the Community and will help the Member States in the efficient implementation of this Directiversquo The Commission (Environment DG) established an information exchange forum (IEF) to assist the work under Article 16(2) and a number of technical working groups have been established under the umbrella of the IEF Both IEF and the technical working groups include representation from Member States and industry as required in Article 16(2)

Preface

vi Version April 2006 SSEIPPCBENE_Draft_1

The aim of this series of documents is to reflect accurately the exchange of information which has taken place as required by Article 16(2) and to provide reference information for the permitting authority to take into account when determining permit conditions By providing relevant information concerning best available techniques these documents should act as valuable tools to drive environmental performance including energy efficiency The special target of this document is to provide a comprehensive energy management structure which makes it possible for companies to demonstrate their energy efficiency and competent authorities to verify it This general structure will later be tailored for different sectors in sectoral BREFs The background and mandate of this work concerning generic energy efficiency techniques for industry differs from other BREFs in the sense that this document is prepared in the IPPC context but it can be used in a broader scope

6 Information Sources This document represents a summary of information collected from a number of sources including in particular the expertise of the groups established to assist the Commission in its work and verified by the Commission services All contributions are gratefully acknowledged

7 How to understand and use this document The information provided in this document is intended to be used as an input to the recommendations for goodbest practices to contribute energy efficiency in IPPC installations When determining BAT and setting BAT-based permit conditions account should always be taken of the overall goal to achieve a high level of protection for the environment as a whole including energy efficiency The rest of this section describes the type of information that is provided in each section of this document Chapter 1 provides general information on the basics of energy and thermodynamics It explains main features of energy and principles of thermodynamics as an introduction for understanding energy applications in industry and their restrictions Chapter 2 provides information on the definitions of energy efficiency relevant for industry and how to develop indicators to monitor energy efficiency Furthermore it deals with different aspects which influence energy efficiency some of them which company has control and some of them not It also gives examples how different system boundaries influence the energy efficiency Chapter 3 provides information on good energy management in industrial installations in broad terms It explains why good structured management is important and which issues will be considered and taken into account in a good system It covers the elements which are crucial to manage energy issues efficiently both from an environmental and economical point of view It gives examples of good management structures approaches audits methodologies and other tools which could be implemented to improve energy efficiency Systematic and transparent way to deal with energy issues is essential to reach best economical and environmental results Chapter 4 provides information on generic energy producing and using systems and unit operations which can be found in several industries It describes energy saving techniques related to these systems (eg steam system) and unit operations (eg motors) The approach is to describe different strategies to improve energy efficiency in these systems and also describe commonly used energy saving techniques (eg heat recovery) separately

Preface

SSEIPPCBENE_Draft_1 Version April 2006 vii

Chapter 5 recommends the best practices to be used in companies to manage energy issues Since the best available techniques change over time this document will be reviewed and updated as appropriate All comments and suggestions should be made to the European IPPC Bureau at the Institute for Prospective Technological Studies at the following address

Edificio Expo cInca Garcilaso sn E-41092 Sevilla Spain Telephone +34 95 4488 284 Fax +34 95 4488 426 e-mail JRC-IPTS-EIPPCBceceuint Internet httpeippcbjrces

SSEIPPCBENE_Draft_1 Version April 2006 ix

Best Available Techniques Reference Document on ENERGY EFFICIENCY TECHNIQUES

EXECUTIVE SUMMARYI PREFACE III SCOPE XVII 1 GENERAL FEATURES ON ENERGY 1

11 Introduction 1 111 Forms of energy 1 112 Energy transfer and storage 2 113 Energy losses 3 114 Exergy 3

12 Principles of thermodynamics 4 121 Characterisation of systems and processes 4 122 Forms of energy storage and transfer 4 123 Properties enthalpy and specific heat 5 124 Properties entropy and exergy 6

13 First and second laws of thermodynamics 7 131 First law of thermodynamics ndash energy balance 7

1311 Energy balance for closed systems 7 1312 Energy balance for open systems7 1313 Calculation of internal energy and enthalpy changes8 1314 First law efficiencies thermal efficiency and coefficient of performance 8

132 Second law of thermodynamics - entropy balance 9 133 Combination of the first and second laws - exergy balance 10

1331 Exergy balance for a closed system 10 1332 Exergy balance for an open system10 1333 Calculation of flow exergy changes11 1334 Second law efficiency exergetic efficiency11

14 Property diagrams tables databanks and computer programs 12 141 Pressure-temperature diagram 12 142 Pressure-specific volume and temperature-specific volume diagrams 13 143 Temperature-entropy diagram 14 144 Enthalpy-entropy diagram 15 145 Property tables databanks and simulation programs 15

15 Identification of inefficiencies 16 151 Case 1 Throttling devices 17 152 Case 2 Heat exchangers 19 153 Case 3 Mixing processes 21

2 ENERGY EFFICIENCY 27 21 Definitions of energy efficiency 27 22 Energy efficiency indicators in industry 28

221 Production processes 29 222 Energy intensity factor and energy efficiency index 29 223 Energy efficiency in production units 30 224 Energy efficiency of a site 34

23 Issues to be considered when defining energy efficiency indicators 35 231 System boundaries 35

2311 Definition of the system boundary35 2312 Examples of system boundaries36 2313 Some remarks on system boundaries 40

232 Other items to be decided by the company 41 233 Structural issues 45

24 Examples of application of energy efficiency 48 241 Mineral oil refineries 48 242 Ethylene cracker 49 243 VAM production 50 244 A rolling mill in a steel works 51 245 Heating of premises 53

3 ENERGY MANAGEMENT IN INDUSTRIAL INSTALLATIONS 55 31 The structure and the content of energy management 55

x Version April 2006 SSEIPPCBENE_Draft_1

311 General features and factors 55 312 Commitment of the top management 58 313 Planning 59

3131 Initial energy audit 59 3132 Energy performance targets 60 3133 Action plan 61

314 Doing 61 3141 Structures and responsibilities 62 3142 Awareness raising and capacity building62 3143 Communication and motivation63

315 Checking 63 3151 Monitoring and measurement 63 3152 Records 64 3153 Periodic energy audits64

316 Acting 64 317 Examples of energy management systems and its implementation 65

32 Methodologies and tools for energy use optimisation and energy efficiency 65 321 Energy audits 65

3211 Audit models66 32111 The scanning models67 32112 The analysing models68 32113 The technical coverage of energy audit models 69

3212 Audit tools 71 322 Energy monitoring 72 323 Energy models 73

3231 Example 1 Electric energy models74 3232 Example 2 Thermal energy models77 3233 Energy diagnosis using the energy models 79

324 Pinch methodology 81 325 Benchmarking 84 326 Assessment methods 88

3261 Time series comparison 88 3262 Comparison with theoretical approaches 89 3263 Benchmarks approaches90

327 Qualification of components in representative conditions 91 328 Cost calculations 93 329 Checklists 93 3210 Good housekeeping 93 3211 E-learning 93

33 Energy services company (ESCO) concept 93 34 Public schemes and tools to motivate energy saving in industry 94

341 Tax deductions for energy saving investments 94 342 Ecology premium 95 343 Support for demonstration projects in energy technology 96 344 Cogeneration certificates (blue certificates) 96 345 Energy planning regulation 97 346 Benchmarking covenant 98 347 Audit covenant 99 348 Energy saving certificates (white certificates) 100 349 EMAT - energy managerrsquos tool 102 3410 Energy saving agreements 103

4 APPLIED ENERGY SAVING TECHNIQUES 105 41 Introduction 105 42 Combustion 106

421 Choice of combustion techniques 106 422 Strategies to decrease losses in general 107 423 High temperature air combustion technology (HiTAC) 111

43 Steam systems 114 431 General features of steam 115 432 Measures to improve steam system performance 117 433 Use of economisers to preheat feed-water 119 434 Prevention removal of scale deposits on heat transfer surfaces 120 435 Minimising blowdown 122 436 Recovering heat from the boiler blowdown 124

SSEIPPCBENE_Draft_1 Version April 2006 xi

437 Implementing a control and repairing programme for steam traps 126 438 Collecting and returning condensate to the boiler for re-use 128 439 Re-use of flash steam 130 4310 Insulation on steam pipes and condensate return pipes 131 4311 Installation of removable insulating pads on valves and fittings 132 4312 Use of flash steam on the premises through recovery of condensate at low pressure 133 4313 Installing an air preheater 134 4314 Minimising boiler short cycling losses 136

44 Power production 137 45 Cogeneration 138

451 Different types of cogeneration 138 452 CHP in soda ash plants 144 453 Stationary reciprocating engine solutions 145 454 Trigeneration 148 455 District cooling 151

46 Waste heat recovery 154 461 Direct heat recovery 155 462 Heat pumps 157 463 Surplus heat recovery at a board mill 161 464 Mechanical vapour recompression (MVR) 163 465 Acid cleaning of heat exchangers 166 466 Heat exchangers with flashed steam - design 168

47 Electric motor driven systems 171 48 Compressed air systems 177

481 General description 177 482 Improvement of full loadno load regulation system 181 483 Variable speed drive technology (VSD) 182 484 Optimising the pressure level 184 485 Reducing leakages 186

49 Pumping systems 187 491 General description 187 492 Choice between steam turbine driven pumps and electrical pumps 188 493 Vacuum pumps replacing steam ejectors 192

410 Drying systems 193 4101 General description 193 4102 Techniques to reduce energy consumption 195

41021 Mechanical processes 195 41022 Computer-aided process controlprocess automation195 41023 Selecting the optimum drying technology 196

411 Process control systems 196 4111 General features 196 4112 Energy management and optimisation software tools 200 4113 Energy management for paper mills 201 4114 Fluidised bed boiler combustion optimisation 204 4115 Steam production and utilisation optimisation using a model predictive controller 205

412 Transport systems 207 413 Energy storage 211

5 BEST PRACTICES 213 51 Generic best practices 214 52 Energy efficiency indicators 214 53 Energy management structure and tools 215 54 Techniques to improve energy efficiency 216

541 Combustion 216 542 Steam systems 217 543 Cogeneration 217 544 Heat recovery 218 545 Electric motor drive systems 218 546 Compressed air systems 219 547 Pumping systems 219 548 Drying systems 219 549 Transport systems 219

6 CONCLUDING REMARKS 221

xii Version April 2006 SSEIPPCBENE_Draft_1

7 REFERENCES 223 8 GLOSSARY 227 9 ANNEXES 233

91 Annex 1 233

SSEIPPCBENE_Draft_1 Version April 2006 xiii

List of figures Figure 11 Pressure-temperature diagram 12 Figure 12 P-v diagram 13 Figure 13 T-v diagram 14 Figure 14 Temperature-entropy diagram 14 Figure 15 Enthalpy-entropy diagram 15 Figure 16 Steam throttling process 18 Figure 17 T-s and h-s diagrams for the steam throttling process of the example 18 Figure 18 Counterflow heat exchanger 20 Figure 19 Reheating process of a steam flow 20 Figure 110 T-s and h-s diagram for the steam reheating process of the example 21 Figure 111 IiRT0 versus molar fraction of one component in the mixture 22 Figure 112 Mixing chamber of two flows 23 Figure 113 T-s diagram for the mixing process of the example 24 Figure 21 Energy vectors in a simple production unit 30 Figure 22 Energy vectors in a production unit 32 Figure 23 Inputs and outputs in a site 34 Figure 24 System boundary ndash old electric motor 36 Figure 25 System boundary ndash new electric motor 37 Figure 26 System boundary ndash electric motor + old pump 37 Figure 27 System boundary ndash electric motor + new pump 38 Figure 28 Electric motor + new pump with constant output 38 Figure 29 New electric motor new pump and old heat exchanger 39 Figure 210 New electric motor new pump and two heat exchangers 40 Figure 211 Inputs and outputs for a vinyl acetate monomer (VAM) plant 50 Figure 212 Flow chart of a rolling mill 51 Figure 213 Specific energy consumption in a rolling mill 52 Figure 214 Specific energy consumption in a rolling mill 53 Figure 215 Energy consumption depending on outdoor temperature 53 Figure 216 Energy consumption depending on outdoor temperature 54 Figure 31 The plan-do-check-act-cycle (PDCA) 57 Figure 32 Continuous improvement of an energy management system 57 Figure 33 Basic energy auditing models 66 Figure 34 The properties of energy audit models 66 Figure 35 Coverage of an industrial site energy audit 69 Figure 36 Coverage of a district heating connected to a residential building energy audit 70 Figure 37 Coverage of a CHP plant energy audit 70 Figure 38 Structure of a monitoring system 72 Figure 39 Monitoring process 73 Figure 310 Power factor of a device depending on the load factor 75 Figure 311 Scheme of energy diagnosis 80 Figure 312 Hot and cold streams in Pinch methodology 81 Figure 313 Energy savings identified by pinch methodology 83 Figure 314 Mechanism when an ESCO is involved 100 Figure 41 Energy balance of a combustion installation 107 Figure 42 Working principle for regenerative burners 111 Figure 43 Different regions of combustion 112 Figure 44 The net heat output of test furnaces resulted by both conventional and HiTAC burners 113 Figure 45 Distribution of the energy content of steam in the sensible and latent component depending on

absolute pressure 116 Figure 46 Back-pressure plant 139 Figure 47 Extraction condensing plant 139 Figure 48 Gas turbine heat recovery boiler 140 Figure 49 Combined cycle power plant 140 Figure 410 Reciprocating plant 141 Figure 411 Comparison between efficiency of condensing power and combined heat and power plant142 Figure 412 Trigeneration compared to separate energy production 148 Figure 413 Trigeneration enables optimised plant operation around the year 149 Figure 414 District cooling in the winter by free cooling technology 152 Figure 415 District cooling by absoption technology in the summer 152 Figure 416 Diagram of a compression heat pump 158 Figure 417 Diagram of an absorption heat pump 159

xiv Version April 2006 SSEIPPCBENE_Draft_1

Figure 418 Heat recovery system connected to the district heating system 162 Figure 419 Simple MVR installation 163 Figure 420 COP versus temperature lift for a typical MVR system 164 Figure 421 Process scheme of Eurallumina alumina refinery 166 Figure 422 Operative cycle of heaters 167 Figure 423 A section of the heater 169 Figure 424 Scales in the tube bundle 170 Figure 425 A compressor motor with a rated output of 24 MW 173 Figure 426 Some methods of capacity control of a centrifugal pump 175 Figure 427 Performance of compressors with different controls 175 Figure 428 Pump power consumption 176 Figure 429 Fans with different controls 176 Figure 430 Compressed air system 178 Figure 431 Energy flow diagram for an inefficient compressed air station 179 Figure 432 Compressor lifecycle costs 183 Figure 433 Different kinds of compressor control 184 Figure 434 Steam distribution scheme of the alumina refinery 189 Figure 435 Bandwidths for the specific secondary energy consumption of different types of dryer when

vaporising water 194 Figure 436 Structure of an energy management tool 200 Figure 437 Paper mill energy management (system layout) 202 Figure 438 Tracking deviations from optimum consumption 202 Figure 439 Steam flow depending on fuel and time 204 Figure 440 Variable definition matrix 206

Scope

SSEIPPCBENE_Draft_1 Version April 2006 xv

List of tables Table 11 Some values of the derivatives 22 Table 12 Maximum values for mistures 23 Table 31 Energy management matrix 56 Table 32 A simple electric model 75 Table 33 Data ina thermal energy model (generators side) 77 Table 34 Data in a thermal energy model (users side) 78 Table 35 Steps in Pinch methodology 82 Table 36 Information template for energy efficiency motivation tools 94 Table 37 Areas covered in the application 102 Table 41 The template for information on energy efficiency techniques 105 Table 42 Higher and lower calorific values of certain fuels 107 Table 43 Differences in heat transfer 121 Table 44 Energy content of blowdown 123 Table 45 Recovered energy from blowdown losses 125 Table 46 Various operating phases of steam traps 126 Table 47 Operating factors for steam losses in steam traps 127 Table 48 Load factor for steam losses 127 Table 49 Percentage of total energy present in the condensate at atmospheric pressure and flash steam

129 Table 410 Percentage of total energy present in the condensate at atmospheric pressure and flash steam

130 Table 411 Heat losses per metre of pipes in function of the operating temperature and insulation

thickness 132 Table 412 Calculation of the Siegert Co-efficient for different types of fuel 135 Table 413 Technical data for the Barajas Airport trigeneration plant 151 Table 414 Components of an electric motor drive system 171 Table 415 Possible energy saving measures in compressed air systems 180 Table 416 Leakage costs 186 Table 91 Saturated water properties 234 Table 92 Superheated water properties I 235 Table 93 Superheated water properties II 236

Scope

SSEIPPCBENE_Draft_1 Version April 2006 xvii

SCOPE This document together with other BREFs in the series (see list on the reverse of the title page) are intended to cover the energy efficiency issues under IPPC Directive This document also responds to the special request from the Commission Communication on the implementation of the European Climate Change Programme (COM(2001)580 final) ECCP concerning energy efficiency in industrial installations The ECCP asks that effective implementation of the energy efficiency provisions of the IPPC Directive are promoted and that a special horizontal BREF addressing generic energy efficiency techniques is prepared The target of this document is to provide information on how to improve energy efficiency in industrial installations by giving generic guidance on how to approach assess implement and deal with energy efficiency related issues along with corresponding permit and supervising procedures Many of the proposed measures tools and methodologies dealt with may also be implemented in non-IPPC installations This document deals with generic energy efficiency techniques and best practices which can be applied in several industrial sectors without duplicating the work done in sectoral BREFs However it can feed other work that is in progress with information and ideas The coverage of this document is as follows bull industrial sectors which use or produce energy and apply generic techniques which are

possible to transfer to other sectors are covered bull it does not develop or conclude on sector specific techniques but will use examples from

various industry sectors to derive generic conclusions bull equipment (eg pumps fans) as parts of systems and installations are dealt with without

drawing conclusions which could conflict with EuP implementing measures bull it does not respond to fuel specific (eg bio fossil waste) issues bull the system boundary is set in most cases round the site but in some cases also smaller or

larger boundaries are considered The main question to be answered in this document is the following How to demonstrate if energy is used and produced efficiently

For finding answers to this question this document deals with the following issues bull what are appropriate definitions for energy efficiency bull what are and how to use energy efficiency indicators bull what methodologies techniques etc contribute to good energy management bull what are the possible measures both techniques and practices to improve energy

efficiency bull what are possible motivation tools To answer all the above-mentioned questions this document deals with the following issues bull energy management including different types of auditing bull methodologies bull monitoring bull indicators and measurements bull applied techniques and good practices

xviii Version April 2006 SSEIPPCBENE_Draft_1

In order to further clarify the scope the following can be said bull because energy efficiency means different things for different stakeholders clarification on

what energy efficiency means in this document is required First a distinction needs to be made between energy efficiency at the macro level (eg national) and at the micro level (eg company level) In this document only the latter is discussed

bull energy efficiency is dealt with from an industrial perspective within the installation boundaries without considering a productrsquos life cycle This is in line with the IPPC Directive which deals with production and not with products The fuel by which energy is produced is also not considered in this document

bull this document deals with production activities in industrial installations but energy demand of products is outside the scope Furthermore fuel specific issues are neither dealt with in this document

bull those techniques and measures to improve energy efficiency which are sector specific are not dealt within here but in sectoral BREFs For example it exists a BREF on large combustions plants where energy efficiency is also covered

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 1

1 GENERAL FEATURES ON ENERGY [2 Valero-Capilla 2005] [3 FEAD and Industry 2005] [97 Kreith 1997] This chapter deals with the basics of energy and thermodynamics It explains the main features of energy and the principles of thermodynamics as an introduction for understanding energy applications and their restrictions in industry There is a lot of generic information on thermodinamics available in the general literature

11 Introduction Energy is needed to fulfil the necessary or imagined needs of people To do this energy is needed directly (eg heating lighting) or indirectly (eg energy in products) Industry needs energy as one production factor to manufacture goods and provide services to the society Decoupling energy demand and supply is a challenging task

111 Forms of energy Energy can take a wide variety of forms There are five main forms of energy generally required in industry bull chemical energy the energy that bonds atoms or ions together (eg fuels) bull mechanical energy associated with motion bull thermal energy (or heat) the internal motion of particles of matter bull electrical (or electromagnetic) energy associated with the electrical charges and the

movement of them bull nuclear energy energy in the nuclei of atoms which can be released by fission or fusion of

the nuclei Chemical energy is stored in fuels and can be converted directly to mechanical energy (combustion engines) or to thermal energy (direct process heating) However most often the chemical energy is converted to a more usable form generally either to electrical energy or mechanical energy to drive machines or thermal energy as the source of a process

Mechanical energy can exist into two states kinetic or potential Kinetic energy is the energy that moving objects have due to their motion For example it can be an alternative motion (eg a piston) a rotary motion (eg transmission shaft) or a waterfall Potential energy is the energy stored in an object due to its position for instance water stored by a dam Thermal energyheat is quantified by temperature It can be created by chemical reactions such as burning nuclear reactions electromagnetic dissipation (as in electric stoves) or mechanical dissipation (such as friction)

Electrical energy or electromagnetic energy is a form of energy present in any electric field or magnetic field or in any volume containing electromagnetic radiation Nuclear energy will not be dealt within this document Energy can also be expressed as primary and secondary energies usually for statistical purposes Primary energy is energy contained in raw fuels and any other forms of energy received by a system as input to the system Primary energies are transformed to secondary energies in energy conversion processes to more convenient forms of energy such as electrical energy

Chapter 1

2 Version April 2006 SSEIPPCBENE_Draft_1

112 Energy transfer and storage Transfer Energy cannot be created or destroyed Energy can only be converted from one form to another (first law of thermodynamics see Section 131) Energy is converted to make it more useful for different purposes in industry and all society Energy found in fossil fuels solar radiation or nuclear fuels needs to be converted into other energy forms such as electrical propulsive or cooling to be useful Energy conversion is any process of converting energy from one form to another The efficiency of a converting machine characterises how well it can convert the energy Energy conversion can be done by eg the following means bull electricity can be turned into mechanical energy by an electrical motor bull inversely mechanical energy can be converted into electricity by an alternator bull thermal energy can be transformed into mechanical energy by a turbine bull electricity can be converted into heat by a resistance bull chemical energy can be turned into heat during a chemical reaction and also into (kinetic)

mechanical energy and heat for instance in an explosion bull an internal combustion engine converts chemical energy in the gasoline to the propulsive

energy that moves a car bull a solar cell converts solar radiation into electrical energy that can then be used to light a

bulb or power a computer Storage The storage of different forms of energy (see Section 111) are quite different Some are difficult or even impossible to store as such Electricity can hardly be stored as such Batteries store potential electrical energy but in fact chemically Mechanical and thermal energies can be stored in the medium term as potential energy water damshot water tanks but in general they are not so easy to store One of the most convenient ways for storing energy is undoubtedly as chemical energy in a material It can be stored for a long and even sometimes very long time It can be transported and it is often easy and quick to implement The most important chemical sources of energy are the fuels

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 3

113 Energy losses Energy losses are very different according to the transformation it undergoes Furthermore the transformation is neither total nor unique eg an electrical motor also generates heat Losses are unavoidable to some extent (second law of thermodynamics see Section 132) The following examples illustrate the losses from a combustion plant and from electricityheat conversion Combustion plant bull the first energy losses are due to incomplete combustion of the fuel Part of the fuel is not

burnt at all or only partially and in this case produces other reactants (such as CO2) than the ones resulting from complete combustion This is an incomplete conversion of chemical energy into thermal energy

bull some other losses are due to an incomplete transfer of the heat of the combustion gases to the watersteam of the boiler losses through the lagging of the combustion chamber and of the boiler losses to the air by the flue-gas losses to the air via the ashes

bull the heat of the combustion gases is mostly transferred to the steam cycle but part of it is transferred to the air instead of the fluid which is required (watersteam)

bull similarly if heat is exported via a heat exchanger there will be some losses by transfer of part of it to the air instead of to the secondary fluid

bull when steam is sent to a turbo generator set part of its energy is transferred to the air by direct heat losses and mechanical frictions in the turbo generator set However most of the losses here are due to the latent heat which is released by steam when condensed at the cold source The latent heat is the energy released or absorbed during a change of state (released when passing from the gaseous state of steam to the liquid state of water) Of course the losses are significantly reduced if this energy can be used as happens in the case of cogeneration

Electricityheat conversion bull when turning electricity into heat nearly 100 of the electricity input will be turned into

heat However converting the heat released by the combustion of a fuel into electricity can typically result a conversion efficiency of about 35 of the fuel energy input Using electricity just for making heat is not considered to be an efficient use of energy since the electricity which is used was most probably made from heat in a thermal cycle So it is much more beneficial when possible to use a heat source directly than to convert heat into electricity then electricity into heat even if the second transformation is made with high efficiency

114 Exergy The term lsquoexergyrsquo is used to describe differences in energy quality in other words exergy shows the maximum useful work obtainable in the system The exergy content of a system indicates its distance from the thermodynamic equilibrium See Section 124 and 133 For instance 1 GJ of steam at 400 degC40 bar contains the same energy as 1 GJ of water at 40 degC but different exergy The usefulness of these energies are really different on the one hand there is 300 kg of steam on the other 6 tonnes of water and steam at 40 bar can be used for generating electricity moving mechanical equipment heating etc but there is little use for water at 40 degC The exergy of low temperature energies can be raised by eg heat pumps

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12 Principles of thermodynamics Thermodynamics is the physics that deals with the relationships and conversions between heat and other forms of energy 121 Characterisation of systems and processes A system (as a thermodynamic concept) is the quantity of matter within the prescribed boundary under consideration everything external to the system is called the surroundings Systems may be considered as closed or open A system can be considered closed if there is no interchange of matter between the system and the surroundings If there is an interchange the system is considered to be open A very important class of systems that is frequently encountered by engineers is steady-flow systems A steady-flow system can be defined as any fixed region-of-space system through which a fluid flows and the properties of this fluid either internal to the system or at its boundaries do not change as time passes Typical examples include air compressors gas turbines steam turbines boilers pumps heat exchangers etc All these devices have in common that each has one or more fluid streams entering and leaving Devices with these characteristics are also known as steady-state steady-flow systems steady-flow control volumes and flow systems Any characteristic of a system is called property Temperature volume pressure or mass are some of the most familiar examples

122 Forms of energy storage and transfer The energy of a system consists of the kinetic potential and internal energies expressed as

mgzmCUPTKNUU PK ++=++=2

2

(J) Equation 11

Where

bull U is the internal energy which is associated with the microscopic forms of energy ie to the motion position and internal state of the atoms or molecules of the substance

bull KN is the kinetic energy which is associated to the motion of the system as a whole relative to some reference frame

bull C is the velocity of the system relative to some fixed reference frame bull m is the mass of the body in motion

bull PT is the change in gravitational potential energy which is associated with the position of the system as a whole (elevation) in the earthrsquos gravitational field

bull g is the gravitational acceleration

bull z is the elevation of the centre of gravity of a system relative to some arbitrarily selected reference frame

Thermal energy is a huge drain of energy when compared with kinetic or potential energies Therefore in many energy analyses these two last energies may be disregarded Energy storage Energy can be stored in numerous forms (some more information in Section 112) The most important encountered forms in thermodynamic applications are internal kinetic and potential energy Other forms of energy such as magnetic electric and surface tension effects are significant only in some specialised cases and will not be considered here

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Energy transfer The forms of energy discussed above which constitute the total energy of a system are static forms of energy and can be stored in a system However energy can also be transformed from one form to another and transferred between systems For closed systems energy can be transferred through work and heat transfer Heat and work are not properties because they depend on the details of a process and not just the end states bull heat (Q) can be defined as energy in transit from one mass to another because of a

temperature difference between the two It accounts for the amount of energy transferred to a closed system during a process by means other than work The transfer of energy occurs only in the direction of decreasing temperature Heat can be transferred in three different ways conduction convection and radiation Conduction is the transfer of energy from the more energetic particles of a substance to the adjacent particles that are less energetic due to interactions between the particles Conduction can take place in solids liquids and gases Convection is the energy transfer between a solid surface at a certain temperature and an adjacent moving gas or liquid at another temperature Finally thermal radiation is emitted by matter as a result of changes in the electronic configurations of the atoms or molecules within it The energy is transported by electromagnetic waves and it requires no intervening medium to propagate and can even take place in vacuum

bull work (W) has the following thermodynamic definition work is done by a system on its surroundings if the sole effect on everything external to the system could have been the raising of a weight Like heat work is also energy in transit

123 Properties enthalpy and specific heat Enthalpy A property related to internal energy U pressure p and volume V is enthalpy H defined by

H = U + pV (J) Equation 12 Or per unit of mass using specific internal energy u and specific volume v (internal energy and volume per unit of mass) as follows h = u + pv (J) Equation 13 Specific heat capacity The property specific heat capacity C (commonly named specific heat) relates energy and temperature The specific heat is defined as the energy required to raise the temperature of a unit mass of a substance by one degree Two different specific heats are usually considered in thermodynamics specific heat at constant volume CV and specific heat at constant pressure CPSpecific heat at constant volume CV expresses the energy required to raise the temperature of the unit mass of a substance by one degree as the volume is maintained as constant The energy required to do the same to the pressure being maintained as constant is the specific heat at constant pressure CP CV and CP are expressed as follows

vv T

uC

partpart

= (JK) Equation 14

pp T

hC

partpart

= (JK) Equation 15

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The values of internal energy enthalpy and heat capacities can be calculated as shown in Section 1313 and they are extensively available through property tables databases and programs for a great variety of substances as explained in Section 145

124 Properties entropy and exergy Entropy The concept of entropy is very important to state the second law of thermodynamics in (see Section 132) a general and usable form When two stable states of a system are connected by different internally reversible processes the integral of the heat interchanged over its temperature is found not to be dependent on process path This proves the existence of the function called entropy which only depends on the state of the properties of the system The change of entropy is defined as follows

(JK) Equation 16

Entropy is an abstract property and can be viewed as a measure of disorder Unlike energy entropy is a non-conserved property However entropy is easily calculated following procedures like those explained in Section 143 Thermodynamic databanks as explained in Section 144 include values of entropy for many substances mixtures and pressure and temperature ranges Exergy Exergy of a thermodynamic system is the maximum theoretical useful work (shaft work or electrical work) obtainable as the system is brought into complete thermodynamic equilibrium with the thermodynamic environment while the system interacts with this environment only (some more information can be found in Section 114) A system is said to be in the dead state when it is in thermodynamic equilibrium with its surroundings In the dead state a system is at the temperature and pressure of its surroundings it has no kinetic or potential energy and it does not interact with the surroundings Exergy can be defined as well as a measure of the departure of the state of a system from the environment Once the environment is specified a value can be assigned to exergy in terms of property values for the system only and exergy can be regarded as a property of the system The value of exergy as defined in Equation 17 cannot be negative and is not conserved but destroyed by irreversibilities The specific exergy on a unit mass basis is e = (u-u0) + p0 (v-v0) ndash T0(s-s0) + C22 + gz (J) Equation 17 Where bull 0 denotes the dead state When a mass flows across the boundaries of a control volume there is an exergy transfer accompanying the mass and work flows This is named lsquospecific flow exergyrsquo or lsquophysical exergyrsquo of a material stream and is given by e = (h-h0) - T0 (s-s0) + C22 + gz (J) Equation 18 Flow exergy is commonly used in the analysis of open systems and calculating it is as simple as any other thermodynamic property as explained in Section 14

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13 First and second laws of thermodynamics The two fundamental and general laws of thermodynamics are (1) energy is conserved and (2) it is impossible to bring about any change or series of changes The sole net result of which is the transfer of energy as heat from a low to a high temperature In other words heat will not flow from low to high temperatures by itself A thermodynamic process will not occur unless it satisfies both the first and the second laws of thermodynamics

131 First law of thermodynamics ndash energy balance The first law of thermodynamics is the general principle of physics and it states that energy is conserved Although the law has been stated in a variety of ways all have essentially the same meaning The following are examples of typical statements bull whenever energy is transformed from one form to another energy is always conserved bull energy can neither be created nor destroyed bull the total sum of all energies remains constant for a given system bull the net energy in the form of heat added or removed from a system that operates in a cyclic

manner equals the net energy in the form of work produced or consumed by the system bull the value of the net work done by or on a closed system undergoing an adiabatic process

between two given states depends solely on the end states and not on the details of the adiabatic process

1311 Energy balance for closed systems For a closed system the first law implies that the change in system energy equals the net energy transfer to the system by means of heat and work That is U2 ndash U1 = Q - W (J) Equation 19 In systems undergoing cycles the net work output equals the net heat transfer to the cycle Wcycle = Qin - Qout (J) Equation 110

1312 Energy balance for open systems Most applications of engineering thermodynamics are conducted on a controlled volume basis In such cases the conservation of the mass principle must be applied The time rate of accumulation of mass within the control volume equals the difference between the total rates of mass flow in and out across the boundary as shown below

sumsum minus=2

21

1 mmdtdm

(kgs) Equation 111

The energy rate balance for such a system is

++minus

+++minus= 2

22

22

1

21

11

22gzChmgzChmWQ

dtdU

(W) Equation 112

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For steady-flow systems the mass flowrates and the rates of energy transfer by heat and work are constant with time

sumsum =2

21

1 mm (kgs) Equation 113

Hence at steady state the first law of thermodynamics can be expressed as

++minus

++=minus 2

22

22

1

21

11

22gzChmgzChmWQ (W) Equation 114

1313 Calculation of internal energy and enthalpy changes The change in internal energy and enthalpy for an ideal gas during a process from state 1 to state 2 is determined as follows

int=minus=∆2

112 )( dTTCuuu v (J) Equation 115

int=minus=∆2

112 )( dTTChhh p (J) Equation 116

The values of CV and CP can be obtained through tables databases and programs for many substances as explained in Section 123 For incompressible substances (those whose specific volume or density is constant) CV = CPand following equations can be applied

(J) Equation 117

Where bull Cav is a C value at the average temperature for small temperature intervals ∆h = ∆u + v∆P (J) Equation 118

1314 First law efficiencies thermal efficiency and coefficient of performance

The thermal efficiency η measures the performance of a heat engine and can be defined as the fraction of the heat input that is converted to net work output

in

outnet

QW =η (-) Equation 119

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It can also be expressed as

in

out

QQ

minus= 1η (-) Equation 120

For a power cycle operating between thermal reservoirs at temperatures TH and TC(T temperature H hot and C cold) the thermal efficiency is

H

C

QQ

minus= 1η (-) Equation 121

The maximum efficiency that can be achieved is given by the Carnot efficiency which is shown in Equation 122 below

H

C

TT

minus= 1η (-) Equation 122

The equations above are also applicable to refrigeration and heat pump cycles operating between two thermal reservoirs but for these QC represents the heat added to the cycle from the cold reservoir at temperature TC and QH is the heat discharged to the hot reservoir at temperature TH More informative coefficients are perhaps the Coefficients of Performance COP of any refrigeration cycle COPR and heat pump cycles COPHP given by

CH

CR QQ

QCOP

minus= (-) Equation 123

CH

HHP QQ

QCOPminus

= (-) Equation 124

Unlike the thermal efficiency the value of COP can be greater than unity This means that the amount of heat removed from the refrigerated space can be greater than the amount of work input

132 Second law of thermodynamics - entropy balance The second law of thermodynamics shows which types of transformations are possible or not and in which direction they occur Like the first law the second can be assumed in many different ways and some of them are listed below bull it is not possible to construct a heat engine which produces no other effect than the

exchange of heat from a single source initially in an equilibrium state and the production of work Heat engines must always reject heat to a thermal-energy reservoir

bull no cyclical device can cause heat to transfer from thermal-energy reservoirs at low temperatures to reservoirs at high temperatures with no other effects

bull the total entropy of an engine and all of the surrounding components that interact with the engine must increase when the heat engine is not completely reversible

bull the only processes that can occur are those for which the entropy of the isolated system increases This statement is known as the increase of entropy principle

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133 Combination of the first and second laws - exergy balance The first and second laws can be combined into a form that is useful for conducting analyses of exergy work potential and the second law efficiencies among others This form also provides additional insight into systems their operation and optimisation

1331 Exergy balance for a closed system The exergy balance for a closed system is obtained with the combination of the energy and entropy balances The exergy change in a closed system is equal to the sum of the exergy transfer accompanying heat the exergy transfer accompanying work minus the destruction of exergy The final equation is

[ ]

ndestructioExergy

workngaccompanyi

transferExergy

heatngaccompanyi

transferExergy

jchangeExergy

TVVpWQTT

EEE σδ 0120

2

1

012 )(1 minusminusminusminus

minus=minus=∆ int 44 344 21

443442143421

(J) Equation 125

bull T0 denotes the temperature at ambient conditions bull p0 denotes pressure at ambient conditions bull Tj is the surface temperature where the heat transfer takes place The term T0σ accounts for the destruction of exergy or thermodynamic irreversibility and is often denoted as I The value of exergy destruction is always positive and ideally zero when no irreversibilities are present within the system As explained in this section if the principal task of any energy analyst is to pinpoint irreversibilities it is quite logical to make use of exergy balances instead of the entropy ones This is because exergy has the familiar units of energy rather than units of energy over temperature and exergy can be easily interpreted as the thermodynamic quality part of an energy stream As explained in this section exergy can easily be calculated as any other thermodynamic property once the properties of the surrounding environment are defined Note that exergy is a definition of thermodynamic availability and equivalence and is not a definition of technical usefulness As an example if natural gas is needed for a given process the same amount of exergy with say steam or coal does not satisfy the needs and could not be used alternatively Lack of interpretation is in many cases the real cause of the not so widely used exergy analyses Energy analysts should be quite knowledgeable about thermodynamics

1332 Exergy balance for an open system The exergy rate balance for a control volume is equal to

ndestructioExergyofRate

transferexergyofRate

eee

iiicvj

j j

changeexergyofRate

cv Iememdt

dVcvpWQTT

dtdE

0

01 minusminus+

minusminus

minus= sumsumsum

4444444444 34444444444 21

(W) Equation 126

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For steady-flow systems the balance obtained is

010 IememWQ

TT

ee

eiii

cvjj j

minusminus+minus

minus= sumsumsum (W) Equation 127

1333 Calculation of flow exergy changes The specific exergy change can be evaluated using following equation

)(2

)()( 21

22

21

2102121 zzgCCssThhee minus+minus

+minusminusminus=minus (Jkg) Equation 128

The values of enthalpy and entropy can be obtained either through property tables or with equations in Sections 123 124 and 131

1334 Second law efficiency exergetic efficiency The thermal efficiency and coefficient of performance defined in Section 1314 are based only on the first law of thermodynamics and make no reference to the best possible performance However the exergetic efficiency or second law efficiency overcomes this deficiency and gives a measure of approximation to reversible operation Exergetic efficiencies are useful for distinguishing means for utilising energy resources that are thermodynamically effective from those that are less so They can be used to evaluate the effectiveness of engineering measures taken to improve the performance of a thermal system The exergetic efficiency is defined in a generic form as the ratio between the exergy recovered and the exergy supplied

E recovered ε= E supplied (-) Equation 129

Exergetic efficiency expressions can take many different forms depending on the analysed system For a heat engine the exergy supplied is the decrease in the exergy of the heat transferred to the engine which is the difference between the exergy of the heat supplied and the exergy of the heat rejected The net work output is the recovered exergy For a refrigerator or heat pump the exergy supplied is the work input and the recovered exergy is the exergy of the heat transferred to the high temperature medium for a heat pump and the exergy of the heat transferred from the low temperature medium for a refrigerator More in general exergy producing systems and exergy dissipating ones can be distinguished The objective of the former is to transfer the exergy of the fuels to the products as much as possible thereby minimising both exergy losses and exergy destructions Most of the energy systems fall within this classification such as turbines compressors pumps boilers and most of the engines On the contrary devices exist whose objective is to dissipate a given flow with the less possible exergy input These devices are for instance draft fans for stack gases dryers or lamps among others From the second law point of view the objective of both types of devices is to dissipate as little exergy as possible The second law efficiency of the first devices is never greater than one On the contrary the second law efficiency of the latter devices needs to be as much greater than one as possible In any case both the numerator namely the product or objective and the denominator namely the expended fuel should be expressed in exergy units

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14 Property diagrams tables databanks and computer programs

In the general literature diagrams tables databanks and computer programs exists on thermodynamic properties of substances

141 Pressure-temperature diagram The p-T diagram also called the phase diagram (Figure 11) shows the three phases of a pure substance separated by a line In each of the single-phase regions (solid liquid and gas) the phase of the substance is fixed by the temperature and pressure conditions The lines between one-phase regions are called two-phase regions and represent the conditions where two phases exist in equilibrium In these areas pressure and temperature are not independent and only one intensive property is required to fix the state of the substance The sublimation line separates the solid and vapour regions the vaporisation line separates the liquid and vapour regions and the melting or fusion line separates the solid and liquid regions A substance being to the left of the vaporisation line is said to be at the state of a sub-cooled or compressed liquid if it is found at the right of the same line the substance is in a superheated vapour state All three lines meet at the triple point where all the phases coexist simultaneously in equilibrium In this case there are no independent intensive properties there is only one pressure and one temperature for a substance in its triple state The so called critical point can be found at the end of the vaporisation line At pressures and temperatures above the critical point the substance is said to be at a supercritical state where no clear distinction can be made between liquid and vapour phases

Substances thatexpand on

freezingSubstances that contract

on freezing

Critical pointS L

LV

Triple point

SV

SOLID

SOLID

P

T

Figure 11 Pressure-temperature diagram

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142 Pressure-specific volume and temperature-specific volume diagrams

Figure 12 and Figure 13 show a pressure-specific volume (P-v) and a temperature-specific volume (T-v) diagram respectively The two-phased region labelled liquid-vapour in both diagrams is commonly called the wet or the dome region The state at the top of that region is again the critical point Inside the dome a substance is a mixture of saturated liquid and saturated vapour The area under a given curve on the P-v diagram representing a quasi equilibrium process is

expressed as dvp

v

vint2

1 which is according to Equation 119 the specific boundary work Therefore P-v diagrams are very useful in the analysis of processes involving boundary work The isotherm lines (states with equal temperature) appearing on the P-v diagram indicate that inside the dome the pressure remains constant at a fixed temperature However in the single-phase liquid and vapour regions the pressure decreases as the specific volume increases Similarly the isobars (states with equal pressure) shown on the T-v diagram indicate that inside the dome the temperature remains constant at a fixed pressure but in the single-phase regions the temperature increases with the specific volume

P

f g

Vapour

TgtTC

Liquid-vapour

Liquid

TltTC

Criticalpoint

TC

VTC = critical temperaturef = saturated liquidg = saturated gas

Figure 12 P-v diagram

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14 Version April 2006 SSEIPPCBENE_Draft_1

V

T

f g

VapourLiquid

Liquid-vapour

PltPC

PgtPC

PC

Criticalpoint

PC = critical pressuref = saturated liquidg = saturated gas

Figure 13 T-v diagram

143 Temperature-entropy diagram Temperature entropy (T-s) diagrams are widely used in thermodynamics because they are very useful in visualising irreversibilities of processes Constant volume constant pressure and constant enthalpy lines can be seen in T-s diagrams The slope of constant volume lines in single-phase regions are always steeper than those of constant pressure lines For superheated vapour states the constant enthalpy lines become almost horizontal as pressure is reduced The pressure change between states in this region can be neglected therefore entropy is the only function when temperature and gases behave more like ideal gases

Since the internally reversible heat transfer is expressed as int=

2

1int TdSQrev (see Equation 16)

the area under the curve on a T-s diagram represents revQint

Vertical lines on T-s diagrams represent processes undergoing isentropic (same entropy) compressionexpansion while horizontal lines inside the dome mean isothermal phase changes (vaporisationcondensation)

s

T

Vapour

p=constv=const

h=constp=const

v=const

Liquid-vapour

Criticalpoint

Liquid

Figure 14 Temperature-entropy diagram

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144 Enthalpy-entropy diagram By means of an enthalpy-entropy diagram (h-s) commonly called Mollier diagram (see Figure 15) the two major properties of interest in the first and second law analysis of open systems are represented The change in enthalpy ∆h corresponds to a vertical line in the h-s diagram and is related to the work changes for turbines compressors etc in adiabatic steady-flow processes The change in entropy ∆s is represented in the diagram by a horizontal line and gives an idea of the irreversibility for an adiabatic process On an h-s diagram constant pressure and constant temperature lines are straight in the dome region In the superheated region constant temperature lines become horizontal meaning that enthalpy and temperature are directly proportional This is the region where the ideal gas model can be reasonably applied

s

h

Liquid Liquid-vapour

Criticalpoint

Vapour

p=const

p=const

T=const

T=const

x=quality

Figure 15 Enthalpy-entropy diagram

145 Property tables databanks and simulation programs For many substances associated with industrial processes properties can be presented in the form of tables They come from experimental data The most frequently listed properties in tables are specific volume internal energy specific enthalpy specific entropy and specific heat Property tables can be found in thermodynamic books and there is also an example in Annex 1 Due to the fact that in one-phase regions two intensive properties must be known to fix the state for superheated vapour and compressed liquid the properties v u h and s are listed versus temperature for selected pressures If there are no available data for a compressed liquid a reasonable approximation is to treat compressed liquid as saturated liquid at the given temperature This is because the compressed liquid properties depend on temperature more strongly than they do on pressure The so called saturation tables are used for saturated liquid and saturated vapour states Since in two-phase regions pressure and temperature are not independent one of the properties is enough to fix the state Therefore in saturation tables the properties v u h and s for saturated liquid and saturated vapour are listed either versus temperature or pressure In the case of a saturated liquid-vapour mixture an additional property called quality (x) must be defined Quality is defined as the vapour mass fraction in a saturated liquid-vapour mixture

(-) Equation 130

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Where mg represents the mass of saturated vapour and mf the mass of saturated liquid The properties of such a mixture are determined by the aid of the saturated tables and the calculated quality is as follows yav = yf+xyfg Equation 131 Where bull y calculated quality bull v specific volume bull u internal energy per unit of mass bull x quality bull yfg mixture of quality (gas and liquid) yfg = yg - yf Equation 132 Tables in the real world are not enough There is a strong need to have thermodynamic properties of many substances both pure and mixed In fact complex thermodynamic data banks and associated physical property models form the heart of any computer energy simulator The need is so important that inaccuracy or unavailable data may lead to the rejection of attractive energy conservation solutions Fortunately a considerable amount of databases and computer programs may be found in thermodynamic literature and on the market A problem arises in having the knowledge to select data with good criteria even if contradictory data are found Quality accurate and up-to-date information is in many cases critical This is a key issue when calculating mixture properties in which departure from non-ideal behaviour is common Some major data compilations can be found from the following sources bull the American Petroleum Institute API bull Beilstein Institute of Organic Chemistry BEILSTEIN bull Design Institute for Physical Property Data DIPPR of AIChE bull Deutsche Gesellshaft fuumlr Chemisches Apparatewesen Chemische Technik und

Biotechnologie eV DECHEMA bull Physical Property Data Service PPDS in the UK For instance DIPPR has a comprehensive pure component data compilation meanwhile a primary source of mixture data is DECHEMA Commercial simulation programs with extensive capabilities for calculating thermodynamic properties can be easily found Three of the most experienced programs are the trademarked ASPEN PLUS HYSIM and PROII However these computer packages may do more than what a common energy saving analyst needs to do or perhaps they perform in a less specialised way On the other side these programs are costly both in effort of handling and money for acquiring and maintaining Intermediate solutions that allow the analyst to compose their own simulating solutions and include pure substance properties are for instance EES Thermoptim and BBlocks Therefore the analyst must devote time in judging which is worth buying Starting from scratch is not very advisable in most cases

15 Identification of inefficiencies Mechanical thermal and chemical equilibrium conditions of a thermodynamic system also imply three causes of disequilibrium or inefficiencies (irreversibilities in thermodynamics) Mechanical irreversibilities are due to pressure changes and always appear in processes that involve friction Entropy generation and exergy destruction are always associated with mechanical irreversibilities the greater the pressure change the greater the irreversibility created within the system

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Thermal irreversibilities appear when there is a finite temperature change within the system as for instance in every heat exchanger The heat passes from a warm body to a cold one spontaneously thereby losing exergy Again the irreversibility produced increases with the temperature change Chemical irreversibilities are due to a chemical disequilibrium occurring in mixtures solutions and chemical reactions For example when water and salt are mixed exergy is destroyed This exergy loss is equivalent to the minimum work that has been previously needed to purify water in order to obtain the salt All atmospheric and water pollution effects are included here It is very easy to contaminate (mix) but a lot of exergy is needed to clean up The thermodynamic analysis of irreversible processes reveals that in order to obtain a good efficiency and save energy it is required to control and minimise all the mechanical thermal and chemical irreversibilities appearing in the plant Three case studies now follow throttling devices (see Section 151) focusing in mechanical irreversibilities heat exchanges (see Section 152) focussing on thermal irreversibilities and mixing processes (see Section 153) focussing on thermal irreversibilities and have been developed in order to illustrate the ideas and calculation methodologies for identifying and minimising irreversibilities

151 Case 1 Throttling devices Throttling devices are very common in industry and are used to control and reduce pressure mainly through valves Since the throttling process is isenthalpic (where the enthalpy up and down flows are equal) no energy is lost and according to the first law of thermodynamics its efficiency is optimal However this is a typical mechanical irreversibility which reduces pressure and increases the entropy of the fluid without giving any additional benefit Consequently exergy is lost and the fluid is less capable of producing energy in a turbine expansion process for instance Therefore if the point is to reduce the pressure of a fluid it is desirable to tend to isentropic expansions providing useful work as an additional result through turbines If this is not possible the working pressure should always be the highest possible because this will avoid the use of compressors or pumps for fluid transportation (additional useful energy) A very frequent practice in industrial installations is to keep the pressure at the inlet of the turbine at the design conditions This usually implies the use and abuse of admission valves to control the turbine According to the second law it is better to have flotation of the pressure specifications (sliding pressure) and to keep the admission valves completely open As a general recommendation valves should be sized as large as possible A satisfactory throttling process can be achieved with a pressure drop of 5 - 10 at maximum flow instead of 25 ndash 50 as it happened in the past where valves were small sized Of course the pump driving the fluid must be also sized according to the variable conditions Finally it must be stressed that pipes also act as throttling devices decreasing the pressure of the fluid flowing through them Therefore a good design with good materials and few obstacles such as unnecessary valves elbows bows etc will limit the exergy losses across the process In any case it is clear that an exergy accounting that considers all the energy levels existing in the plant must be performed because from the first law point of view irreversibilities are very difficult or impossible to identify

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Numerical example During a unit commissioning in a power plant a steam extraction coming from the high pressure turbine (P = 40 kgcm2 T = 350 ordmC) is used in order to feed a turbopump Since the turbopump operates at an inlet pressure of 8 kgcm2 the steam coming from the high pressure turbine must be throttled (see Figure 16) In the following thermodynamic example variables of the steam are evaluated at the inlet and outlet of the valve The process is sketched on the T-s and h-s diagrams (see Figure 17) and the exergy flow is obtained when the nominal flow is 45000 kgh

1 2

P1= 40 kgcm2

T1= 350 degCP2= 8 kgcm2

Figure 16 Steam throttling process

Solution The first law of thermodynamics reveals that the process is isenthalpic since no work or heat transfer is associated with the throttling process 0 = m1(h2-h1) gt h2 = h1 Equation 133 The specific enthalpy and entropy obtained through the property tables are bull At P1 and T1

o h1 = 309195 kJkg and s1 = 658 kJkg K bull At P2 and h2 = h1

o T2 = 319 ordmC o S2 = 730 kJkg K

S

T

T1

T2

s2s1

1

2

h = 309195 kJkg

h

1 2

Ss2s1

h1 = h2

Figure 17 T-s and h-s diagrams for the steam throttling process of the example

The specific flow exergy is calculated as e = h ndash T0s Equation 134

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Where T0 = 273 K and the potential and kinetic energy are considered negligible Hence e1 = 309195 ndash 273 x 658 = 129561 kJkg and e2 = 309195 ndash 273 x 730 = 109905 kJkg This process is completely irreversible (mechanical irreversibility) The exergy loss is obtained through an exergy balance to the system Since there is no heat or work transfer the exergy balance reduces to

152 Case 2 Heat exchangers Heat exchangers are devices where two streams exchange heat Every heat transfer is the result of a temperature difference and thus is always associated with entropy generation and exergy destruction Therefore there is a contradiction between the ideas of minimum exergy loss and maximum heat transfer efficiency (see Section 461) In a counterflow heat exchanger like the one shown in Figure 18 where a hot fluid at T1in is cooled down to T1out by releasing heat to a cold fluid that heats up from T2in to T2out therefore the exergy loss in the process is calculated as follows The change in kinetic and potential energy are usually negligible and no work interactions are present For a first approximation the pressure drop can also be considered negligible The irreversibility created in the heat exchanger is given by I = (e1in + e2in) ndash (e1out + e2out) = (h1in + h2in) ndash (h1out + h2out)

T1out T2out - T [(s1in + s2in) ndash (s1out + s2out)] = T0 [ m1Cp1ln T1in

+m2Cp2 ln T2in Equation 135

It can be demonstrated from the equation above that I is always positive and increases with the temperature differences at the inlet and outlet of the fluids in the counterflow exchanger and between the top and bottom in a parallel-flow one In any case a counterflow exchanger is always better than a concurrent one (parallel-flow) from the exergy point of view because exergy is always being giving off to a system at a similar temperature The irreversibilities taking place in heat exchangers are due to two factors heat transfer caused by the temperature difference and pressure loss associated with the fluid circulation Both fluid friction and irreversible heat transfer can be reduced decreasing the fluid flow However in order to obtain the same effect of heat exchange a larger transfer area is required ie larger heat exchangers must be designed The idea of extending the use of counterflow heat exchange to the whole installation ie extending it to all flows to be heated or cooled in the plant so that the temperature change through which heat must flow is reasonably low leads to the energy integration of processes and the use of energy cascades This is the philosophy of the pinch methodology developed for the integration of heat exchanger networks The integration can also be extended to power cycles heat pumps and refrigeration cycles in the most efficient way In summary this procedure assures the lowest steam consumption (or any another heat source) and the lowest cooling water (or any other cold source) under the thermodynamic and technical conditions that may be assessed

Chapter 1

20 Version April 2006 SSEIPPCBENE_Draft_1

Fluid T1in

Fluid T2in

Fluid T1out

Fluid T2out

Figure 18 Counterflow heat exchanger

Numerical example In a boiler reheater (see Figure 19) 1100000 kgh of steam is heated from 350 to 540 ordmC at a pressure of 40 kgcm2 The heat absorbed by the steam comes from the exhaust gases of a combustion process The average temperature where the heat transfer occurs is 1000 ordmC In Figure 110 the process is sketched on the T-s and h-s diagrams and the heat absorbed by the steam and exergy losses is determined

P1 = 40 kgcm2

T1 = 350 degC

Q

P2 = 40 kgcm2

T2 = 540 degC

Figure 19 Reheating process of a steam flow

Solution The energy balance of the system considered in Figure 19 is m (h2 ndash h1) = Q Equation 136 The specific enthalpy and entropy obtained through the property tables is bull At P1 and T1

o h1 = 309195 kJkg and o s1 = 658 kJkg K

bull At P2 and T2

o h2 = 353085 kJkg and o s2 = 721 kJkg K

Hence the heat transfer obtained is Q = 11100000 x (353085 ndash 309195) = 4389 kJkg = 4827 x 106 kJh T-s and h-s diagrams are shown in Figure 110

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 21

S

T

S1

1

2

S2

P = 40 kgcm2

h

12

SS1 S2

P = 40 kgcm2h1

h2

Figure 110 T-s and h-s diagram for the steam reheating process of the example

The specific flow exergy is calculated as e= h ndash T0s Equation 137 Where T0 = 273 K and the potential and kinetic energy are considered negligible Hence e1 = 309195 ndash 273 x 658 = 129561 kJkg and e2 = 353085 ndash 273 x 721 = 156252 kJkg The exergy loss generated is given by

153 Case 3 Mixing processes The mixing of fluids with different compositions or temperatures is another process very common in industry This concept includes tempering processes for temperature control mixing processes for quality control substance purifying processes distillation etc For example an adiabatic mixture of two different ideal gases flows at the same temperature and pressure and n1 and n2 equals the number of moles of each flow The generation of entropy in the mixing process corresponds to the sum of the entropy increase of each gas due to their expansions from P to their new partial pressure of the mixture Hence

summinus=

minus

+= ii xxR

PP

RnPP

Rnnn

lnlnln1 22

1

1

2

1

σ (JK) Equation 138

Chapter 1

22 Version April 2006 SSEIPPCBENE_Draft_1

Since Pi = xiPi and sum=

i

ii

n

nx

the exergy loss is calculated as follows I = T0σ = - RT0sum xi ln xi (J) Equation 139 This expression is always positive and symmetrical with respect to the value xi = 05 It tends to zero when xi tends to zero (maximum purity) Figure 111 shows IiRT0 versus the molar fraction of one component in the mixture xi The maximum exergy is reached when xi = 0 butunder these conditions it is relatively easy to separate both components As the mixture is being purified the exergy loss per mol of the separated component increases

08

Mole fraction of one component x

02 100806040

02

04

06

Ixiln xi

x

R=minusΣ

xilnximinus

Figure 111 IiRT0 versus molar fraction of one component in the mixture

For the considered binary system the irreversibility is equal to

[ ])1ln()1(ln0 xxxxRTI minusminus+minus= and

minus

minus=)1(

ln0 xxRT

dxdI

Equation 140 Some of the values of this derivative are presented in Table 11

x IRT0 (1RT0) dIdx 010 0325 220 001 0056 496

10 - 3 791 x 10 - 3 691 10 - 4 102 x 10 - 3 921

Table 11 Some values of the derivatives

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 23

This derivative indicates the work required to improve the purity of the product and the easiness to pollute In other words the exergy value of the product is related with this derivative Multicomponent mixtures behave in the same way The maximum value of the function -sum xi ln xi that takes place for equimolar mixtures is shown in Table 12

N - sumxilnxi N - sumxilnxi2 0693 5 1609 3 1099 7 1946 4 1386 10 2302

Table 12 Maximum values for mistures

As the number of components of the mixture increases the irreversibility effects become more dramatic These ideas lead to a set of recommendations for energy saving in mixing processes Firstly and most importantly mixing processes must be avoided whenever it is possible Obtaining high quality steam or a very pure substance requires a great amount of exergy that is mostly lost when mixed with a lower quality flow (even if the energy loss is zero) Secondly the quality specifications of a certain product must not be exceeded and above all once they are exceeded they should never be mixed with lower quality flows This way if a product with 01 purity is mixed equimolarly with another of 1 purity the final product will have 055 purity but the exergy value of this product will decrease

significantly with respect to the individual flows since this is related with the derivative dxdI

and not with the mean composition value Some quality specifications of products should be reviewed and should be made lsquosofterrsquo if possible This is something basic in the chemical industry in which it is very common to find partially refined matter mixed with over purified products or mixtures of products coming from two parallel units for achieving an average purity Numerical example A steam flow at a pressure of 180 kgcm2 and a temperature of 550ordmC is mixed with saturated liquid at 180 kgcm2 in order to reach the temperature design specifications of a certain equipment (see Figure 112) In Figure 113 the final temperature of the mixture and the exergy loss is determined when the mass flow of steam is 1100000 kgh and of the liquid 30000 kgh

Hot stream (1)

Cold stream (2)Mixed stream (3)

P3 = 180 kgcm2

P1 = 180 kgcm2 T1 = 550 degC x = 0

P2 = 180 kgcm2 x = 0

Figure 112 Mixing chamber of two flows

Chapter 1

24 Version April 2006 SSEIPPCBENE_Draft_1

Solution The mass balance of the system is m1 + m2 = m3 Equation 141 Since there is no work or heat transfer to the process and the kinetic and potential energy can be assumed to be zero the energy balance reduces to m1 h1 + m2 h2 = (m2 + m1) h3 Equation 142 At P1 and T1 the specific enthalpy and entropy obtained through the property tables is h1 = 34142 kJkg and s1 = 641 kJkg K respectively For the saturated liquid at the cold stream (2) only one property (pressure in this case) is needed to fix the state h2 = 171706 kJkg and s2 = 385 kJkg K From the energy balance applied above

At the mixed stream (3) with h3 and P3 T3 = 534 ordmC and s3 = 635 kJkg K The change in specific enthalpy and entropy can be obtained with the help of the property tables in Annex 1 The specific flow exergy is calculated as Equation 137 where T0 = 273 K and the potential and kinetic energy are considered negligible Hence e1 = 166452 kJkg e2 = 66667 kJkg and e3 = 163455 kJkg The irreversibility is obtained through the exergy balance I = m1(e1 - e3) + m2 (e2 ndash e3) =gt I = 11 x 106(166452 ndash 163455) + 30 x 103(66667 ndash 163455) = 376 x 106 kJh = 104 MW The T-s diagram is shown in Figure 113

S

T

T1

T3

T2

S2 S3 S1

P = 180 kgcm2

1

2

3

Figure 113 T-s diagram for the mixing process of the example

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 25

Remarks for all three case studies Irreversibilities are the effects of any improvable energy system Besides avoiding finite pressure temperature andor chemical potential differences the causes of poor energy design come from decoupling supply and demand Time plays an important role in energy efficient systems Energy systems spontaneously decrease its pressure temperature and chemical potential to reach equilibrium with its surroundings To avoid this there are two strategies bull to couple energy donors with energy acceptors immediately bull storage to enclose a system within rigid walls for pressure adiabatic walls for temperature

andor to confine the chemical systems into metastable states In other words confine the systems into reservoirs that maintain their intensive properties constant with time

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 27

2 ENERGY EFFICIENCY [4 Cefic 2005] [5 Hardell and Fors 2005] This chapter deals with definitions of energy efficiency relevant for industry and how to develop indicators to monitor energy efficiency Furthermore it deals with different aspects which influence energy efficiency some of which a company has control over and some of them not It also gives examples on how different system boundaries influence energy efficiency

21 Definitions of energy efficiency Defining energy efficiency is a complex task It is not possible to present a solution that will fit in all cases and will satisfy all stakeholders When the term energy efficiency is used the meaning of the term is usually not defined When it is defined the meaning depends on the context in which it is used The main reason is that everyone does not deal with energy in the same way or use the same system boundary It may be simple to describe the meaning of energy efficiency for a single component or a subsystem whereas some difficulties arise as soon as it comes to definitions of energy efficiency for complex industrial plants Because energy efficiency means different things for different stakeholders clarification on what energy efficiency means in this document is required First a distinction needs to be made between energy efficiency at the macro level (eg national) and at the micro level (eg company level) In this document only the latter is discussed (see Scope) Furthermore the main focus of this document is on physical energy efficiency although economic efficiency will be touched on as well In this document energy efficiency is dealt with from an industrial perspective within the installation boundaries without considering a productrsquos life cycle This is in line with the IPPC Directive which deals with production and not with products The fuel by which energy is produced is also not considered in this document There is not a commonly agreed definition of energy efficiency in the EU The IPPC Directive does not define energy efficiency either However it requires IPPC installations to be driven energy efficiently and energy efficiency is part of the BAT consideration and should be addressed in permit application and permit conditions Thus to fulfil the requirements of demonstrating energy efficiency good indicators are needed Energy efficiency has been defined eg in the following ways bull a ratio between an output of performance service goods and energy and an input of

energy A definition can be found in the Common Position No 342005 on Energy and Use Efficiency and Energy Service Directive (9376EEC) where energy efficiency is defined According to this definition the replacement of other fuels by renewables does not improve energy efficiency Also energy efficiency improvement is defined in the same Common Position as an increase in energy end-use efficiency as a result of technological behavioural andor economic changes These definitions have a broader scope than just energy efficiency in industry

bull to obtain an unchanged output value at a reduced energy consumption level (the Swedish Energy Agency)

bull to obtain an increased output value with unchanged energy consumption or to obtain an output value that in relative terms surpasses the increase in energy consumption (the Swedish Energy Agency)

bull the amount of energy consumed per unit of productoutput bull the amount of energy consumed per unit of feedstock

Chapter 2

28 Version April 2006 SSEIPPCBENE_Draft_1

bull energy consumption per unit of product where the consumption of energy is from energy carriers This does not refer to non-energy consumption in the form of feedstocks The energy consumption from secondary energy carriers will be allocated back to the net caloric value (lowest combustion value) of the primary energy carriers Net electricity purchases will be offset at a generation yield requiring the approval of the independent authority When this is used the determination of the proportion of feedstock in energy consumption for each relevant processing plant typically requires the approval of the independent authority [13 Dijkstra ]

In industry the most commonly used definition for energy efficiency is the amount of energy consumed per unit of productoutput which can also be called specific energy consumption or energy intensity factor Improving energy efficiency therefore means reducing the amount of energy required to produce a unit of product This definition will mainly be used in this document The definition looks deceptively simple However once one tries to quantify the concept for monitoring processes experience shows that a framework is required to better define and measure energy efficiency This framework is provided in Section 22 The definition as such does say much about the issue of whether energy is used or produced efficiently To be informative and useful energy efficiency must be compared to something (another unit company over time) and for comparison there must be rules In the case of comparing energy efficiency it is especially important to define system boundaries so that all users are speaking equally As it simplest the definition neither takes a view on how efficiently energy is produced nor how lsquowastersquo energy is used after the system boundary Eg these issues and several others must be decided transparently so that it is possible to evaluate improvements of energy efficiency All these issues will be dealt with in Section 23 Energy efficiency is considered mainly from the perspective of a single industrial company and from the perspective of a production site grouping several production processesunits However the best energy efficiency for a site is not always equal to the sum of the optimum of the energy efficiency of the contained production processesunitscomponents De-optimisation of the energy efficiency of one or more production processesunits may be required to achieve the optimum energy efficiency of the site That is why it is crucial to understand how the definition of a system boundary will influence energy efficiency Furthermore by extending system boundaries outside a companyrsquos activities and by integrating industrial energy production and consumption with the needs of community outside the site the total energy efficiency could be increased eg by providing low value energy for heating purposes in the neighbourhood

22 Energy efficiency indicators in industry Definitions used for energy efficiency were discussed in Section 21 This section express how energy efficiency and indicators are developed for individual industrial production processesunitssites It explains what and how to consider the relevant issues The main target of the indicators is to make a self analysis possible or to compare units to other units or to other companies The importance of clear decisions of system boundaries energy vectors (energy flows) and the way to deal with other related issues (eg wastefuel electricity conversion factor) is expressed

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 29

221 Production processes A production processunit is a process which takes in one or more feeds and converts these into one or more valuable products and in doing so consumes energy Examples of production processesunitssites are bull a gas powered electricity plant takes in gas as its feedstock and the product of this

production process is electricity The energy used is the energy available within the gas Electricity can be also produced in a combined heat and power plant and then the total efficiency is of course better

bull a refinery takes in crude oil and transforms this into gasoline diesel fuel oil and a number of other products A part of these products is burned internally to provide the necessary energy for the conversion process Usually some electricity also needs to be imported unless a cogeneration plant is installed within the refinery in which case the refinery may become a net exporter of electricity

bull a steam cracker takes in liquid and gaseous feeds from a refinery and converts these to ethylene and propylene plus a number of by-products Part of the energy consumed is generated internally in the process supplemented by imports of steam electricity and fuel

bull the feeding to the rolling mill in a steel works consists of approximately 2 decimetres thick flat steel plates that are to be rolled out to bands with a thickness of a few millimetres The rolling mill consists of furnaces rolling mill equipment cooling equipment and support systems including pumps fans hydraulics and lubricating systems lights a mechanical workshop staff space changing rooms etc See Section 244

After defining energy efficiency indicators it will be possible to measure and evaluate the changes in efficiency eg demonstrate that energy is usedproduced efficiently

222 Energy intensity factor and energy efficiency index To show how energy efficiency is developed over time in a company or to make benchmarks between different companies the following indicators may be used the energy intensity factor and the energy efficiency index The energy intensity factor is often called the specific energy consumption and it expresses the amount of energy used to produce the given product(s) How to develop the structure to define energy efficiency and indicators for production units and sites will be expressed in Sections 223 and 224 The main purpose of the energy efficiency indicators is to be able to monitor the progress of the energy efficiency of a given production unit over time and to see the impact of energy efficiency improvement measures and projects on the energy performance of the production processunit In its simplest form the energy intensity factor (EIF) can be defined as EIF = (energy imported ndash energy exported)products produced Equation 21 EIF is a number with dimensions eg GJtonne The energy efficiency index (EEI) is defined by dividing a reference energy intensity factor by the energy intensity factor EEI = EIFrefEIF Equation 22 EIFref can either be a reference number which is generally accepted by the industry sector to which the production process belongs or it can be the energy intensity factor of the production process at a given reference year

Chapter 2

30 Version April 2006 SSEIPPCBENE_Draft_1

The energy efficiency index is a dimensionless number and can be used to for instance measure the progress on energy efficiency of the given process over time EIF is a number that decreases with increasing energy efficiency whereas EEI is a number that increases Energy management therefore targets the lowest possible EIF and the highest possible EEI EIF shows how much energy is used to produce given products but without any reference to previous achievements That is why the value of one single figure alone is not very big EEI shows the trend and is more useful For monitoring purposes the time frame on which the energy efficiency is calculated is best taken for long periods (eg months or years) For example on an hourly basis the energy efficiency indicator may show large fluctuations for a continuous process and it would actually not even make sense for a batch process These fluctuations are smoothed out on longer period basis While Equation 21 and Equation 22 look deceptively simple experience shows that the definitions leave room for interpretation and issues like system boundaries energy vectors and how to deal with different fuels must be defined and decided before use them especially when comparing one production process with another In addition to the two main indicators dealt with here there are also other indicators and sub-indicators One example of a sub-indicator is a pressure level in a compressing system which clearly indicates energy efficiency

223 Energy efficiency in production units In the following two examples the concepts of EIF and EEI are illustrated Example 1 Simple case Figure 21 shows an example of a simple production unit For transparency reasons the handled process will be without energy exports and with only one feedstock and one product The production process makes use of steam electricity and fuel

SteamEsin

Productionunit

Main product P

Fuelimport

Efin

ElectricityEein

Feed F

Figure 21 Energy vectors in a simple production unit

The EIF of this process is given by

Equation 23

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 31

Where bull Esin energy supplied to the process via steam to produce an amount of product P bull Eein energy supplied to the process via electricity to produce an amount of product P bull Efin energy supplied to the process via fuel to produce an amount of product P In Equation 23 it is essential that the various energy vectors (energy flows) are expressed as primary energy and on the same footing For instance 1 MWh of electricity requires more energy to produce than 1 MWh of steam as electricity is typically generated with an efficiency of 35 ndash 55 and steam with an efficiency of 85 - 95 The energy use of the different energy vectors in Equation 23 therefore needs to be expressed in primary energy This includes the efficiency to produce that energy vector (see also Section 232) An example of a calculation of energy efficiencyAssume that to produce 1 tonne of product P1 the following energy vectors have to be used bull 001 tonne of fuel bull 10 kWh of electricity bull 01 tonne of steam Now assume further the following bull lower calorific value of fuel = 50 GJtonne bull efficiency to produce electricity = 40 bull steam is generated from water at 25 degC bull the difference between the enthalpy of steam and the enthalpy of water at

25 degC = 28 GJtonne bull steam is generated with an efficiency of 85 To produce 1 tonne of product P1 the energy consumption is as follows bull Efin = 001 tonne fuel x 50 GJtonne = 050 GJ bull Eein = 10 kWh x 00036 GJkWh x 104 = 009 GJ bull Esin = 01 tonne steam x 28 GJtonne x 1085 = 033 GJ The EIF of this process is then given by bull EIF = (050 + 009 + 033) GJtonne = 092 GJtonne For the concept of EEI assume that this is the reference EIF Now assume that the plant carries out a number of energy efficiency improvement projects so that a year later the energy consumption of the production process has become bull 001 tonne of fuel bull 15 kWh of electricity bull 005 tonne of steam As a result of these energy efficiency improvement projects the new EIF of the process is bull EIF = (05 + 0135 + 0165) GJtonne = 08 The EEI of this process is then bull EEI = 09208 = 115 This indicates that the energy efficiency of the production process has increased by 15

Chapter 2

32 Version April 2006 SSEIPPCBENE_Draft_1

Example 2 More general case Figure 22 deals with a more general case when there is both export of energy and internal recycling of fuel The general case presented here is believed to be sufficiently flexible to be applicable for most industries

Production unit

Recycled fuel Efrec

Main products P1

Other products P2

ElectricityEeout

OtherEoout

Wastelosses W (incinerationflareeffluentto environment)

SteamEsout

Feed F1

Feed Fn

SteamEsin

ElectricityEein

OtherEoin

Fuel importEfin

Recycled fuel Pf

Figure 22 Energy vectors in a production unit

The energy intensity factor EIF of this process is then defined as follows

Equation 24

This generic formula can be applied to each production processunit or site but its various components have to be adapted to each specific production processunitsite The unit of this indicator is (unit of energy)(unit of mass) usually GJt product or MWht product Some consideration to take into account when applying Equation 24 (some also applicable to Equation 23) are described in the seven points follow

1 Feedproduct flows (Fi Pi)

In the horizontal direction the mass-flow of the products is shown in Figure 22 The feeds Fiare the different raw materials used to produce the product The products coming out of the process are split into main products P1 and by-products These by-products are split in two fractions a fraction which is recycled as fuel (Pf) and the remaining other products (P2) An example that can be derived from the petrochemical industry is the ethylene steam crackers where energy consumption can be expressed in GJ per tonne ethylene in GJ per tonne olefins (ethylene + propylene) or in GJ per tonne of high value chemicals (olefins + butadiene + benzene + pure hydrogen) This approach is also valid in the chlor-alkali field where consumptions are usually related to the tonne of Cl2

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 33

2 Energy vectors flows (Ei)

Energy vectors are different types of energy flows going and going into the unit In the vertical direction of Figure 22 the energy imported and the energy exported which is used elsewhere are shown The following energy vectors are considered bull Es = steam andor hot water bull Ee = electricity to the process bull Ef = fuel (gas liquid solid) A split is made between the externally purchased fuel and the

fuel which is internally recycled in the process bull Eo = other this covers any utility which requires energy to be produced Examples are hot

oil and cooling water This cooling water requires energy to produce it (energy is required to operate the pumps circulating cooling water and the fans on the cooling towers)

It is important that on the export side only those energy vectors which are lsquousefullyrsquo used after a main processunit in another process are counted In particular the energy associated with cooling of the product to cooling water or air can never be included as the lsquoenergy outrsquo in Equation 24 Energy is consumed to produce cooling water (operation of pumps and fans) but this energy is not always included which is similar to compressed air and N2 Heat losses to the air should also never be counted

3 Different steam levels (Es)

The production plant could be using or producing more than one type of steam (different pressures andor temperatures) Each of these steam levels needs to be included in the term EsHot water if used (or produced and used by another production plant) should be included Each level of steam may have to produce its own efficiency factor

4 Waste flows (W) Each process will also generate an amount of waste products These waste products can be solids liquids or gaseous and may be bull disposed of to landfill (solids only) or by incineration bull be used as fuel (Pf) or bull recycled The relevance of this waste stream will be discussed in more detail in Section 232

5 Fuel or product or waste (E0 Pf)

In Figure 22 fuel is not shown as an exported energy vector The reason for this is that fuel is considered as a product rather than an energy carrier and that the fuel value which would be attributed to the fuel is already present in the feed going to the production unit This philosophy is standard within refineries and the chemical industry Other industries may apply different practices For instance in the chlor-alkali industry some operators count the H2 (a co-product of the Cl2 and NaOH produced) as an energy vector independent of whether this H2 is subsequently used as a chemical or as a fuel (only the H2 flared is not counted) It is therefore important to establish the rules for defining energy efficiency specific to a given industrial sector such as feeds products energy carriers imported and energy carriers exported

Chapter 2

34 Version April 2006 SSEIPPCBENE_Draft_1

6 Time frame The energy intensity factor can be calculated on any desired time frame (hour week month year) The preferred time basis to compare energy efficiency is however a month or a year as this will better capture and level recurring energy consuming disturbances in the process For instance a process may have low relative energy consumption during normal operation but may have frequent shutdowns and restarts related to fouling which consume significant amounts of energy the monthly or yearly energy intensity factor will better capture the effect of these recurring events which measure the energy efficiency of the process

7 Measured or estimated Equation 24 assumes that the different energy vectors to the production process are known However for a typical production process the different utility consumptions (eg cooling water nitrogen steam tracing steam to a turbine electricity) are not always measured Often only the major individual utility consumptions of the production process are measured in order to control the process (eg steam to a reboiler fuel to a furnace) The total energy consumption is then the sum of many individual contributors of which some are measured and some are lsquoestimatedrsquo Rules for estimation must be defined and documented in a transparent way

224 Energy efficiency of a site Complex production sites operate more than one production processunits To define energy efficiency of a whole site it has to be divided into smaller units which contain process units and utility units The energy vectors around a production site can be schematically represented as in Figure 23

Unit Unit

Unit Utilities

Energy imported

Products out

Energy exported

Feeds in

Figure 23 Inputs and outputs in a site

A production site may make different types of products each having its own energy intensity factor It is therefore not always easy to define a meaningful energy efficiency indicator for a site The indicator may be the following

Equation 25

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 35

An issue which needs to be addressed when dividing the production sites into production units (see Section 232) is whether the utility centre should be seen as a separate production unit Usually this is the case as the utility centre produces utilities for more than one production unit The next issue is whether this utility centre will have its own energy consumption or whether it just converts one energy vector in another The utility section in itself may be divided in several sections for instance it could be divided in a part related to the storage and loadingunloading area a part related to hot utilities (steam) and a part related to cold utilities (cooling water N2 compressed air) The following equation should always be verified

sectionutility byusedEnergy PEIF site by the usedEnergy units i

i +lowast= sum=

iEquation 26

For implementation of energy management in the site it is essential to divide the site into its production units including the exact system boundary of these production units to clearly define the energy flows in and out of the site and between the different production units (Unit boxes in the Figure 23) This then clearly defines the way in which the energy efficiency of a given production process is calculated This break-up of a site into production units will depend on the complexity of the production site and has to be decided ndash in every single case ndash by the operator responsible

23 Issues to be considered when defining energy efficiency indicators

In Sections 223 and 224 it was discussed how to develop energy efficiency for a production unit and for a site Sections 231 and 232 discusses some important issues that can be decided by the company and which should be taken into account in the definition of energy efficiency and indicators Section 233 discusses structural issues that are not typically under the decision of a single company but influence the definition of energy efficiency

231 System boundaries

2311 Definition of the system boundary It is most important to clearly define the system boundaries of a processunit when defining the efficiency of a processunitsite (eg whether the boilers are included in the main process unit or whether they are independent) When this has been decided once the same decisions will always apply Steam boilersSteam boilers may be included as an individual unit or as a part of process unit For instance on small sites with only one production process on the site the steam boiler will often be included in the system boundary of the production process The primary energy source in this case will be the fuels burned on the steam boiler In contrast on large sites which often have common boilers for all processes the steam boiler will often be left out of the system boundary of the production process and the main energy carrier will be steam rather than fuel

Chapter 2

36 Version April 2006 SSEIPPCBENE_Draft_1

Auxiliary unitsAnother issue is when auxiliary units are included in the system boundary An example is the case of gasoline hydrotreaters in a steam cracker Gasoline is a co-product of a steam cracker (hence is counted in P2 rather than P1 in Figure 22) Before it can be added to the gasoline pool it needs however to be hydrotreated to saturate the olefins and diolefins present and to remove the sulphur components Most operators would treat the gasoline hydrotreater as a separate unit of the steam cracker However in some sites the gasoline hydrotreater is integrated to the cracker so that for simplicity purposes it is sometimes included within the cracker system boundary Not surprisingly those crackers which include the gasoline hydrotreater in their system boundary will tend to have higher energy consumptions than those which do not This of course does not imply that their energy efficiency is lower Components and sub-systemsIn Section 2312 there are several examples of how the definition of a system boundary influences the efficiency

2312 Examples of system boundaries In this section it will be illustrated how the efficiency changes when a system boundary is extended from a single component to a unit The section deals with single components subsystems or aggregate systems ie equipment types that are frequently to be found in the manufacturing and the process industries A number of examples have been chosen to illustrate the complications that may arise when trying to define the results of different measures for energy efficiency improvements Starting with the consideration of the efficiency of components and subsystems the further discussion takes into account what happens when a lot of subsystems are interconnected as is the case in industrial plants System 1 Old electric motorAn electric motor has been chosen as an example to show the differences in system boundaries In the company concerned an overview was made of existing motor drives and it was found that this motor was very old (see Figure 24) The electric power was 100 kW The efficiency of the motor was 90 and accordingly the mechanical output power was 90 kW

Old electric motor

System boundary

Electric power 100 kW

Mechanicalpower (90 kW)

Power input (100 kW) Output value (90 kW) Efficiency (90 )

Figure 24 System boundary ndash old electric motor

System 2 New electric motorTo improve the efficiency the motor was replaced by a high efficiency motor The effects of this change are shown in Figure 25

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 37

New electric motor

(937 )

Electric power 96 kW

Mechanicalpower (90 kW)

System Boundary

Power input (96 kW) Output value (90 kW) Efficiency improvement (4 kW)Output unchanged

Figure 25 System boundary ndash new electric motor

The electric power needed to produce the same output power 90 kW is now 96 kW due to the higher efficiency of the new motor The energy efficiency improvement is thus 4 kW

System 3 New electric motor and old pumpAs shown in Figure 26 an electric motor is used to operate a pump that provides cooling water for a cooling system The combination of pump and drive is regarded here as one component The output value of this component is the hydraulic power in the form of cooling water flow and pressure Due to the low efficiency of the pump the output value is limited to 45 kW

New electric motor and old pump

(937 )

Electric power 96 kW

System boundary

Power input (96 kW) Output value (45 kW) Efficiency (47 )Output unchanged

Hydraulic power (45 kW)

Cooling water

(50 )

Figure 26 System boundary ndash electric motor + old pump

System 4 New electric motor and new pumpSix months after the replacement of the motor it was found to be necessary to replace the old pump by a new one thereby increasing the pump efficiency from 50 to about 80 The result of the replacement is shown in Figure 27

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38 Version April 2006 SSEIPPCBENE_Draft_1

New electric motor and new pump

(937 )

Electric power 90 kW

System boundary

Power input (90 kW) Output value (67 kW) Efficiency (75 )

Hydraulic power (67 kW)

(80)

Figure 27 System boundary ndash electric motor + new pump

The efficiency of the new equipment is evidently much higher than the previous one The hydraulic power has increased from 45 to 67 kW What improvement of energy efficiency has been attained if one Figure 26 and Figure 27 are compared A reduction of the input power by 6 kW Or an increase of the hydraulic power by 22 kW Or the sum of these changes ie 28 kW As was indicated in Figure 26 the cooling system worked properly even at a hydraulic power of 45 kW What is the benefit of an increase of the hydraulic power by 50 to 67 kW Does it mean that the pumping losses have now been transferred to a control valve and the piping system That was certainly not the intended aim of the replacement of components

System 5 New electric pump new pump and constant output valueAn unbiassed study of the cooling system might have shown that a hydraulic power of 45 kW was sufficient and in this case the shaft power can be estimated at 4508 = 56 kW The electric power needed to drive the motor would then be about 560937 = 60 kW See Figure 28

New electric motor and new pump with constant output value

(937 )

Electric power 60 kW

Power input (60 kW) Output value (45 kW) Efficiency (75 )

Hydraulic power (45 kW)

(80 )

Figure 28 Electric motor + new pump with constant output

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SSEIPPCBENE_Draft_1 Version April 2006 39

In this case the power input was 40 kW lower than before see Figure 24 The question is whether it could have been possible to reduce the size of both motor and pump without harmful effects on the cooling Or could it even be possible to reduce the required hydraulic power to eg 20 kW These types of questions are rarely brought up for discussion and even so no answers will generally be given Still in many cases asking good questions may be the starting-point for profitable improvements to energy efficiency

System 6 System 5 coupled with an heat exchangerIn Figure 29 the system boundary has been extended and the subsystem now includes a new motor a new pump and an old heat exchanger for the cooling process The process cooling power is 13000 kWth (th = thermal)

Hydraulicpower (67 kW)

New electric motor new pump and old heat exchanger

System boundaryCooling

water

(80)Heat from process

(13000 kWth)

Electric power 90 kW

Control valve

13000 kWth

Power input (90 kW) Output value 1 Process cooling 13000 kWth

Output value 2 Hydraulic power 67 kW

Figure 29 New electric motor new pump and old heat exchanger

The output value is represented by the removal of process heat and hydraulic power due to increased water flow and pressure How is the efficiency of the entire system to be defined And how will the efficiency be changed if the cooling needs decrease to 8000 kW caused by a reduction of the utilisation of production capacity

System 7 System 6 with recovery of heatDue to environmental concerns a decision was taken by the company to reduce the emissions of carbon and nitrogen dioxides by recovering heat from the cooling water thereby reducing the use of oil in the heating plant (see Figure 210)

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40 Version April 2006 SSEIPPCBENE_Draft_1

Electric power 90 kW

System boundary Coolingwater

(80)

Power input 90 kW

Control valve

Output value 1 Process cooling 8000 kWth

Heat from process 8000 kWth

Heat recovered replacing fuel oil for heating of premises 4000 kWth

Hydraulic power67 kW

unused heat4000 kWth

Output value 3 Hydraulic power 67 kWth

8000 kWth

Output value 2 Recovered heat 4000 kWth

Figure 210 New electric motor new pump and two heat exchangers

It is evident that the heat recovery arrangement represents an increased output value of the subsystem To estimate the value of the heat recovery in more detail the oil-fired heating plant needs to be considered as well The value of the reduction of the oil consumption the reduction of emissions and the decreasing heat recovery from hot flue-gases from the heating plant need to be taken into account In this case like in most others the subsystems are interconnected which means that the energy efficiency of one subsystem often has an influence on the efficiency of another

2313 Some remarks on system boundaries bull the importance of defining system boundaries is emphasised There are no general rules to

be applied but the lack of definitions can easily cause ambiguities in the understanding of what is included in a system

bull the more narrow the system boundary the easier will it be to state the energy consumption and the output value (See Figure 24 and Figure 25) In complex systems difficulties will often arise when trying to add up different energy savings

bull when the system boundaries are extended (see Figure 26 Figure 27 and Figure 28) to include a pump the output value will increase considerably when installing a new and modern pump The efficiency will increase from 47 to 75

bull in Figure 29 the system boundary has been further extended The major output value is represented by the cooling of process heat In comparison the produced hydraulic power is of minor importance

bull in Figure 210 the cooling power has been reduced considerably entailing reduced production The reason for this is a lower customer demand or changed market conditions Furthermore heat recovery has been introduced The input power to the motor is identical in Figure 29 and Figure 210 but in reality it would be lower in Figure 210 as the cooling demand has been reduced

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232 Other items to be decided by the company

1 Denominator in energy intensity factor and energy efficiency index In most cases it is quite clear that the denominator is the productoutput However sometimes it may be relevant to use the feedstock as a divisor and furthermore in cases when several products are produced over time it should be considered which is the most relevant denominator to achieve the best results bull products co-products and feedstock - in the simplest case the production unit will produce

one main product which can then be used as the divisor In some cases a number of equally important products or a number of important co-products can be produced Where appropriate the sum of these products can be used as the divisor Otherwise the boundaries have to be taken in order to have a meaningful consistence between the energy balance and the products balance

bull in some cases it may be more meaningful to use the amount of feedstock as the divisor This is often the case for mineral oil refineries where the number of product streams is high (eg typically 5 to 7 stream products for an atmospheric crude distillation) and constant and the number of feed streams is low (typically one stream) This divisor is recommended if the energy consumption of a given production unit is determined mainly by the amount of feedstock taken in and less by the amount of product coming out which could be the case when the latter quantity depends strongly on the quality of the feedstock However using feedstock as a divisor cannot take into accout a lost of efficiency of the process

bull several products in batch or in campaigns - special attention should be paid to sites making several different products either in batch or in campaigns As an example a polymer plant could make polymer grades A B and C These grades are made in campaigns for instance grade A may be produced for two weeks then grade B for four weeks and then grade C for one week before producing grade A again The market may determine the production quantities of these various grades and the relative fractions of these grades may vary from year to year Each grade may have its specific energy consumption for instance grade A may consume more energy per unit of product than grade B which itself consumes more energy than grade C To be able to monitor the energy efficiency indicator of the process it may be useful to define a reference energy efficiency indicator per grade (based on the average energy consumption for that given grade) The relevant energy efficiency indicator over a specific period could then be defined

period during produced Cand BAproducts ofSumconsidered periodover unit productionbyusedEnergy

irefCBAi

i EIFxEEI

lowast=

sum= Equation 27

Where xi is the fraction of grade i on total product produced over the given period and EIFrefi is the reference energy efficiency factor for grade i (calculated for instance by averaging the energy efficiency indicator over a reference period when only grade i was produced This is also applicable when the production plant produces only one product but with different specifications and each having a different energy usage

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2 Internal production and use of energy In several processes (eg refineries black liquor in pulp and paper plants) fuel that is produced in the process is consumed internally It is essential that the energy in this fuel is taken into account when looking at the energy efficiency of a process Indeed as shown in Section 222 refineries would have very low energy consumptions as all liquid and gaseous fuels (unless natural gas is used) consumed in the refining process are generated internally from the crude oil imported Typically 4 ndash 8 of the crude oil imported is converted into fuels which are consumed internally The only energy vector imported is then electricity (which is a small contribution compared to fuels burned) When the refinery is moreover equipped with a cogeneration facility it may be exporting electricity while increasing the internal fuel consumption According to the Equation 21 and Equation 22 a refinery equipped with a cogeneration facility would become a net energy producer Clearly this does not seem a good reflection of reality as common sense suggests that refineries consume significant amounts of energy Being aware of the above-mentioned issues it must be stated that system boundaries and energy vectors can be freely chosen but once defined for a specific plant these should be binding

3 Waste and flare recovery WasteAny process generates a quantity of solids liquid andor gaseous waste Often this waste will be recycled as a material or exported to an external incineration company Consider the case where the waste is sent to an external incinerator company Now assume that the production site finds a way to use this waste internally eg as fuel on its boilers or its furnaces Some reflection is required as to whether this improves the energy efficiency of the production unitsite bull the internal use of this waste reduces the need for external fuels but the overall energy

consumption still stays the same bull on the other hand the incinerator company may have an installation where the fuel value of

that waste is recovered via the production of steam In this case the rerouting of the waste stream for use as an internal fuel rather than sending it to an incinerator company may not result in any overall improvement of the energy efficiency when looking at the total picture of production company + incinerator company

In the proposed Equation 24 no credit is given for recovering waste as fuel However the switch from external incineration to internal use may be driven by commercial conditions Some industrial sectors may however have a different point of view and valorise the internal use of waste in their energy efficiency It is important that each industrial sector andor company clearly defines the standard practice applied

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FlareAny gas sent to flare is burned without recovery of any of the calories contained in the flare gas The reason is that the flare is really a safety device and well maintained operated and designed sites will have under normal operating conditions a small to negligible flow to flare Most sites will however have a constant small flow to the flare due to eg leaking relief valves and venting due to loadingunloading operations of storage tanks Some sites have therefore decided to install a flare gas recovery system which recovers this small flow and recycles it to the site fuel gas system Now suppose a production process which previously did not have a flare gas recovery system decides to install one This will reduce the external consumption of fuel gas whereas the overall fuel gas consumption of the process remains the same It is extremely important to define whether a credit for this fuel gas recovery system is allowed This is especially important if one production process recovers not only its own flare losses but also the losses to flare of other production processes on the site From the above considerations it should be clear that it is important to agree on the rules of how to deal with waste when setting up the framework to define the EIFEEI of a processunit One possibility is to define for a given process the reference practice on the amount of waste generated and to what extent it is recycled and to give an energy credit to those operators who are able to use the waste in a more efficient way than the reference case In any case it is essential that each industry defines clearly how to deal with wastes to allow a fair comparison between competing production processes

4 Primary energy conversion factor for electricity To be able to compare different forms of energy vectors it is necessary to define the concept of primary energy For electricity this is the quantity of energy required to produce one unit of electricity For instance current gas powered electricity stations based on combined cycle technology have an efficiency of approximately 55 to convert gas to electricity (defined as the amount of electricity out (in GJ)lower combustion value of gas going in) With CHP it is possible to reach 85 efficiency Different countries may use different conversion factors depending on the actual mix of plants used to produce electricity (eg hydropower combustion plants nuclear) Moreover this efficiency factor may increase over time as older plants are closed and more efficient plants are taken in operation Again it is important to clearly define which efficiency factor should be used Examples of defining the primary energy conversation factor bull when monitoring the energy efficiency improvement of a production process over time it

is important that in the definition of EIF and EEI the electricity conversion factor is kept constant If not it is not possible to separate the effect of an improvement in the energy efficiency of the process itself and the effect of the improvement of the energy efficiency of the electricity production in the country where the production process is located

bull however when reviewing the impact on the energy efficiency of a process when switching from one energy vector to electricity (eg changing from a steam turbine to an electric motor) it could make sense to use the actual electricity efficiency production factor of the country This allows the operator to look at what the best solution is for the combined total picture of the production process and the electricity production which may have another optimum than that of the production process alone

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5 Steam A definition which is often used for steam is the following (also see Section 43) Energetic value of steam = hs-hwnb Equation 28 Where bull hs enthalpy of steam bull hw enthalpy of boiler feed-water (after deaeration) bull nb thermal efficiency of boiler Often this thermal efficiency only takes into account the losses of heat in the stack of the boiler The deaerator is often not seen as part of the boiler (often this deaerator is common to many boilers and furnaces) Hence the following energy inputs are sometimes not taken into account for defining the energy value of steam bull energy required to pump boiler feed-water to operating pressure of the boiler bull heat added to boiler feed-water to bring it to the temperature of the deaerator bull steam sparged in the deaerator to remove oxygen from the boiler feed-water bull energy consumed by the air fan providing forced draft to the boiler

The difference in the energy required to produce the steam and the energetic value of the steam will then be counted at the site level rather than at the production process level At site level the steam will be allocated to the utilities plant (see Section 224) This is in principle not a problem The approach presented in Equation 22 and Equation 24 allows measurements to be made in the improvement of energy efficiency of a process itself and decoupling it from improvements in the energy efficiency of the steam generation process However again for a comparison between different plants making the same product one needs to make a comparison based on the same assumptions for the energetic value determination of steam

6 Load factor the reduction of the specific energy consumption (energy intensity factor EIF) with an increasing production rate is quite normal and is caused by two factors bull the production equipment will be operating for longer periods when the production rate is

high This means that the idling periods become shorter Some types of equipment run continuously even during non-production times This period will be reduced when the non-production time gets shorter (see Figure 214)

bull there is a base energy consumption that does not depend on the utilisation of production capacity This consumption is related to the use of lighting fans for ventilation office machines etc Neither is the heating of the premises dependant on the production but rather on the outdoor temperature as is shown in Figure 216 At higher production rates the consumption will be spread over more tonnes of products

This will be taken into account by the sectorsite-specific correction factor

7 Standards For some components and systems there are already energy efficiency standards (eg boilers motors) which are minimum requirements for appliances and systems

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233 Structural issues In addition to items dealt within Sections 231 and 232 related to internal issues to be decided when deciding on energy efficiency indicators there are several more structural issues which influence energy efficiency and should be considered and understood when deciding the system boundaries In this section there are some examples of issues companies may face and when decisions must be made on how these measures and changes influence the energy efficiency and how to update the indicators not to lose transparency However in all cases if structural changes are implemented also reference performance for energy indicators should be updated The origin and changes in energy efficiency are sometimes difficult to interpret The factors to influence energy efficiency can be active measures of company policy to improve energy efficiency by investments in processes or utilities or some measures over which the company does not have full control Effects by improvements of practices are in every case difficult to measure evaluate and maintain The decision of system boundaries and energy vectors (energy flows) should be made in a transparent way to follow the logic and decide what the real energy efficiency measures are and what the structural changes In some cases structural changes may improve energy efficiency and in some cases not this also depends on the system boundary When changes happen it should be easy to update the data Some examples follow and relate to the manufacturing and process industries In these cases system boundaries are drawn around the company If system boundaries are different eg extended to cover energy production plants in the country the recommendationoutcome would be different

1 Changes in the utilisation of production capacity Changes in production may have a significant impact on specific energy consumption Such changes are often caused by fluctuations on the market the competitiveness of the company and the buyersrsquo demand for the product In cases when the changes are due to market fluctuations and beyond the companyrsquos control they should not be quoted as energy efficiency measures If on the other hand the utilisation of capacity will be changed due to improved production planning meaning eg that the plant will be operated more intensely during fewer shifts this change should be regarded as an action to improve the energy efficiency (see Figure 213)

2 Changes in production technology Changes in production technology may be carried through eg as a result of technical development or because of new components or technical systems being available on the market Obsolete technical systems may need to be replaced and new control systems may need to be introduced to improve the production efficiency The introduction of such changes of production technology may also lead to improvements of energy efficiency Changes in production technology leading to more efficient energy use will be regarded as measures for energy efficiency improvements

3 Product development In some cases new units may need to be added to a production process to meet the market demand or to comply with new product specifications or with environmental requirements In these cases the EEI may deteriorate after the new unit has been put into operation because the new unit requires additional energy to work This does not mean that the site has suddenly neglected its management of energy

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An example of this situation was the adaptation of the refineries in years 2000 ndash 2005 to meet the new fuel specifications (low sulphur diesel and gasoline) set by the EURO IV regulation which has led to an increase of the refineries energy consumption Another example is from the pulp and paper industry which makes improvements of the fibers used in the process which leads to a reduction of energy use Somewhat later the quality of the finished product was also improved and this required an increased grinding After these two steps in technical development it turns out that the total energy use has increased

4 Lifecycle of a product A steel industry improves the strength of the delivered steel products The energy consumption in the new processes will increase The customers can reduce the plate thicknesses in their products by several tens of per cents The steel industry will experience an increase of the energy consumption per tonne product whereas the customers will benefit from the weight reductions in their final products

5 Changes in the production layout Changes in the production layout may eg mean that unprofitable production lines will be shut down media support systems will be exchanged similar lines of business will be merged etc Energy consumption will be changed as a consequence but this change will if regarded from a company standpoint be looked upon as a secondary effect Changes in the production layout can also be regarded to be measures for energy efficiency improvements

6 Close down of the manufacturing of a high energy product A company closes down the manufacturing of a product that requires high energy input Both the total and the specific energy consumption will be reduced This can be claimed to be a measure to improve the energy efficiency in spite of the fact that no other measures have been taken

7 Outsourcing By outsourcing the supply of media a company could eg shut off its compressed air centre The energy consumption could thus be reduced by buying compressed air from an external source The energy use will of course be increase by the supplier of compressed air The change must be clearly taken into account in the updating of energy efficiency indicators but it is not an energy efficiency measure

8 Laying out of process steps to other companies A company may for instance lay out the enamelling of plates to another company This is an example of an energy intensive process that is moved out of the first company but should not be looked upon as an action for energy efficiency improvements An automobile industry decides to increase their purchase of components instead of manufacturing such components themselves The result will be that the total and the specific energy consumption will decrease This must be taken into account in the updating of energy efficiency indicators

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9 Energy integration Internal power production without the additional supply of primary energy sources is an obvious means of improving energy efficiency If it is connected with an exchange of energy with surrounding enterprises system boundaries need to be defined and possible ambiguities settled When comparing electric energy with primary energy sources a conversion factor needs to be applied In the case of an additional supply of primary energy to a CHP plant in the company this may be regarded as an energy efficiency improvement

10 Use of oxygen in a combustion plant A company that increases the use of oxygen in a combustion plant will increase combustion efficiency and reduce fuel purchases Oxygen is not denoted as an energy source and the company may claim that they have improved their energy efficiency

11 Site or company integration Over the last few decades integration of industries has developed eg chemical sites with a high degree of integration have been formed This strategy offers considerable economic advantages This has resulted in complex sites with many operators present and with the utilities being generated either by one of these operators or even by a third party It may also result in complex energy flows between the different operators In general these big integrated complexes offer the highest potential for an efficient use of energy through integration However special caution is called for when defining the system boundary for energy efficiency for such complex sites In an isolated examination of a production process certain energy uses might seem inefficient even though they constitute a highly efficient approach within the integrated system of the site This may result in a situation where single operators are not always operating at their most optimum energy efficiency point but are compensated via commercial incentives in order to obtain the most competitive commercial environment for the integration of the site as a whole Some examples of benefits due to integration are bull the use of steam in a drying process seems to be less energy efficient than the direct use of

natural gas However when considering that this low pressure steam stems from a CHP process combined with highly efficient electricity generation the question of energy efficiency must be viewed in a different light

bull cogeneration plants located at the production site are not always owned by the production site but are often a joint venture with the local electricity generation company whereby the steam is owned by the site operator and the electricity is owned by the electricity company Care should therefore be taken in how these facilities are accounted for

bull when electricity is generated and consumed at the same site much lower transmission losses are expected and then the conclusion is evident that energy efficiency at integrated sites ndash which are quite common at chemical industry locations ndash is usually very high

bull within a highly integrated system residues from production processes are returned into the energy cycle Some examples are the return of waste heat steam into the steam network the use of hydrogen from the electrolysis process as a fuel substitute gas in the power plant process or as a chemical (eg raw material in hydrogen peroxide production) and the incineration of production residues in power plant boilers

All this makes it obvious that selecting appropriate system boundaries to define the energy efficiency of production processes is a sensitive matter

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48 Version April 2006 SSEIPPCBENE_Draft_1

24 Examples of application of energy efficiency 241 Mineral oil refineries The refineries already take seriously into account energy efficiency issues because energy costs represent more than 50 of global operating costs On a single refinery level energy efficiency can be followed by the energy intensity factor as defined in Section 222 In fact it is simpler to use the ratio between globally consumed energy on the site to the amount of treated crude which is equivalent to the EIF Following this ratio against time requires interpretation in order to clarify what comes from energy management and what comes from other factors However this ratio cannot be used for the purpose of comparing the energetic performance of different refineries as all refineries are different in complexities schemes processed crudes and production mixes All these parameters affect the energy needs of the refineries An attempt to catch this complexity is the Solomon Energy Benchmark for refineries For refineries Solomon associates have introduced the concept of the energy intensity index (EII) Solomon associates carry out a worldwide benchmark study of refineries every two years It covers all aspects such as capacity maintenance costs operational expenditure and also energy efficiency The energy efficiency is measured via the EII indicator which is defined as follows

Total actual refinery energy consumed EII = 100 x

Σ(Unit utilised capacity x Unit energy standard) + Sensible heat + Offsite energy

Equation 29 In Equation 29 bull the numerator is the total actual refinery energy consumption (expressed in lower heating

value) and equals the total consumption of fuelelectricity (both import and internal generation) but also takes into account any export of steam andor electricity Electricity from the external grid is converted to primary energy using a standard efficiency factor of 375

bull the denominator is the standard energy consumption according to Solomon (called guide energy) and consists of three main elements o the sum of the guide energies for each of the production units this guide energies are

calculated by multiplying the unit utilised capacity (normal throughput or feed rate) with a unit specific energy standard factor provided by Solomon for each unit For some production units this energy factor depends on feed quality (eg crude density)operation severity (catalytic reformers catalytic crackers etc)type of production facility etc These guide energies per unit are summed to give the total standard energy consumption for all of the refineries production facilities according to Solomon

o a sensible heat factor this factor accounts for the energy required to raise the plant input from ambient temperature to 1044 degC The basis for the plant input is all gross raw material input streams (and their respective densities) that are lsquoprocessedrsquo in process units Blend stocks are not taken into account

o an offsite energy factor this factor accounts for the energy consumed in utility distribution systems and operation of product blending tank farms (tank heating heating of rundown lines terminalling facilities) and environmental facilities The basis for the calculation is the raw material input to process units as well as to blending operations and a complexity factor of the refinery

The EII is dimensionless and in contrast to the definition of EEI presented in Section 222 decreases with increasing energy efficiency

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The EII attempts to compare the energy efficiencies of refineries having different complexities and different units Still this tool is considered by the refining industry as an imperfect tool for comparison purposes at best Some refineries that have a poor EII have few opportunities for improving energy efficiency whereas others with a good EII sometimes still have a large potential for improvement Moreover the EII does not give a good insight to the areasunits that need improvement The detailed breakdown of the site into main production units can be of more help in this respect to identify opportunities for improving energy efficiency

242 Ethylene cracker Ethylene crackers convert feedstock coming from the refinery into ethylene and propylene which form the main feedstock for the polymers industry Ethylene crackers are highly energy intensive Energy costs represent more than 50 of the operational costs of a unit Feedstocks (Fi) typically are naphtha LPG and gasoil coming from refineries The main products (P1) are ethylene and propylene (see Figure 22) Within the industry however it is the custom to add three other high value products to the main products for comparison purposes butadiene benzene and hydrogen Butadiene and benzene do not in fact come out as pure products in a cracker Butadiene is part of the C4 stream and benzene of the cracker gasoline stream They are usually extracted in dedicated extraction units which do not form part of the overall picture of the ethylene crackers Usually the ratio of these high value products to ethylene varies in a narrow window (between 17 and 23) and will depend on cracking conditions and feedstock qualitytype For plants where the economics are mostly driven by ethylene production a more meaningful energy indicator might be to divide energy use by ethylene production rather than by high value chemicals Energy vectors

bull steam a typical ethylene cracker would usually have several steam levels (a high pressure level of approx 100 barg a medium pressure level of approx 20 barg and low pressure level of approx 4 barg) Depending on the configuration the cracker will import steam at some levels and export at other levels

bull electricity most crackers are net electricity consumers Those equipped with cogeneration may be net exporters of electricity Within the industry the convention is to use a conversion factor of 375 to convert electricity to primary energy when comparing different plants

bull hot water most crackers produce relatively large amounts of hot water However in most cases the temperature of this hot water is too low for use by other plants but in some cases integration with other plants or outside consumers is possible In this case a credit should be given for export of these calories So an improvement of energy efficiency is determined by an lsquoexternalrsquo circumstance independent of the lsquointrinsicrsquo performance characteristics of the unit under examination that is the actual possibility of using an output stream for a duty that otherwise should be satisfied with additional primary energy As a consequence two units with the same lsquointrinsicrsquo performancersquo would be rated differently if only one of them can find an energy use for one of its output streams (heat integration)

bull fuel most crackers produce a liquid fuel (pyrolysis fuel oil) and gaseous fuel (a methane rich mixture) Most of the gaseous fuel is recycled to fire the ethylene furnaces Depending on the configuration and mode of operation the gaseous fuel produced may be self sufficient to fire all the furnaces and the rest of fuel gas is exported or there may still be a deficit so the import of an external fuel is required which is typically natural gas Only the fuel consumed internally by the ethylene cracker is taken into account in the energy balance All fuels exported are counted as products (this is logic as the fuel value was already present in the feedstock)

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bull cooling water all crackers use cooling water Sometimes cooling towers are part of the ethylene cracker however this cooling water comes from cooling towers which also supply cooling water to other production units In this case the energy related to the production of cooling water is often not reported when calculating the energy efficiency of the process

bull ethylene processes also use other utilities such as N2 and compressed air Often these utilities are produced centrally on the site or by a third party The energy related to these utilities is often not counted

243 VAM production Some of the components of the proposed Equation 24 Section 223 to calculate the energy intensity factor (EIF) may not be applicable for each process Therefore it has to be modified to the prevailing needs As an example a vinyl acetate monomer (VAM) plant is taken Several components of a VAM plant are not being measured or quantified (here marked with ()) whereas others can easily be named (here marked with ()) see Figure 211

VAM plant

Electrical power

Steam

Cooling water

Utilities

Catalyst inhibitor

Ethylene

Acetic acid

Oxygen

Recycled steam

Condensate

Cooling water return

Light ends

Heavy ends

Purge gas

Waste gas

Heat losses (isolation)

VAM

Water

CO2

Input Output

Figure 211 Inputs and outputs for a vinyl acetate monomer (VAM) plant

As stated in Section 223 heat losses via cooling water return and isolation should never be counted in the EIF or EEI Waste gas and purge gas should not be counted if it is incinerated without heat recovery For those terms it may however be useful to gain some insight into their order of magnitude to verify the economic potential needed to reduce these losses or waste streams In contrast more reflection is required on the other terms such as light and heavy ends or if waste andor purge gas are valorised in other processes In the proposed Equation 24 these streams were not included as it is assumed that the fuel content of these streams is already present in the feedstock However it is the responsibility of the operator to define how to account for these terms

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244 A rolling mill in a steel works The feeding to a rolling mill consists of approximately 2 decimetres thick flat steel plates that are to be rolled out to bands with a thickness of a few millimetres The rolling mill consists of furnaces rolling mill equipment cooling equipment and support systems including pumps fans hydraulics and lubricating systems lights a mechanical workshop staff space changing rooms etc A flow chart of a rolling mill is shown in Figure 212

Furnace

Furnace

Furnace

Rolling equipment

Boiler

Compressor

Cooling bed

Hundreds of pumps and fans at different locationsHundreds of pumps and fans at different locations

Slabs (materialsto be rolled)

Liquefiedpetroleum gas Electricity Cooling water Air

Exhaustgases

Air Scrap(reject

products)

Coolingwater Heat

lossesRolled

products

Figure 212 Flow chart of a rolling mill In this case several different primary energy sources are involved However the following discussion is restricted to the use of electric energy The number of electrically driven components or subsystems in a rolling mill can be estimated at more than one thousand The electric energy consumption can be registered easily with reliable electricity meters The steel production may either mean the weight of slabs entering the rolling mill or the weight of rolled and approved final products The difference corresponds to the weight of scraps that may fall at different stages in the rolling mill An analysis of data taken from an existing rolling mill during a period of 11 weeks was made and some of the results are shown in Figure 213 The energy consumption varied between around 120 and 80 kWh per tonne delivered products dependent on how many tonnes that were produced per week The average consumption was thus 100 kWhtonne and the variation plusmn 20 No energy saving measures were taken during this period

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52 Version April 2006 SSEIPPCBENE_Draft_1

Specific energy consumption in a rolling mill

200

600

1000

1400

010000 20000

kWh

tonn

e

Tonnesweek

Figure 213 Specific energy consumption in a rolling mill

The reduction of the specific energy consumption (energy intensity factor EIF) with an increasing production rate is quite normal and is caused by two factors bull the production equipment will be operating for longer periods when the production rate is

high This means that the idling periods become shorter Some types of equipment are running continuously even during non-production time This type of energy consumption will be reduced when the non-production time gets shorter

bull there is a base energy consumption that does not depend on the utilisation of production capacity This consumption is related to the use of lighting fans for ventilation office machines etc At higher production rates the consumption will be spread over more tonnes of products

The decrease in the specific energy consumption with increasing production rate is thus caused by fluctuations in market conditions which are beyond the companyrsquos control The question is if increasing the production and thereby reducing the specific energy consumption should be regarded as a measure for energy efficiency improvement

A program for improvement of the energy efficiency was later carried out at the rolling mill A number of measures were taken with the aim of decreasing the energy consumption and the results of these measures are illustrated in Figure 214

In this case a direct result of the energy saving measures could be observed The results appeared to be largely independent of the production rate As can be seen in Figure 214 it is possible to separate the results of energy saving efforts and results caused by other factors such as the utilisation of capacity

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SSEIPPCBENE_Draft_1 Version April 2006 53

Specific energy consumption in a rolling mill

10000 20000

Tonnesweek

kWh

tonn

e Energy efficiencyImprovements as aresult of an energysaving programme

Reduction of the energyconsumption as a resultof increased production

1400

1000

600

0

200

Figure 214 Specific energy consumption in a rolling mill

It is also obvious that interpretation difficulties will arise when comparing the specific energy consumption month by month or year by year The specific energy consumption may very well increase from one period to the next though a number of energy saving measures have been taken In this case the effect of such measures is not large enough to compensate for the increase in energy consumption due to low production rates

245 Heating of premises The heating of premises represents another case where the variation of the energy consumption to a great extent is beyond the userrsquos control The energy use is strongly dependent on the outdoor temperature as is shown in Figure 215

-20 0

Energy consumption forheating (MWhweek)

Weekly average outdoortemperature (degC)

Figure 215 Energy consumption depending on outdoor temperature

If measures like heat recovery from the outlet of ventilation air or improvement of house insulation are taken the graphline in Figure 215 will be moved downwards as seen in Figure 216 Estimates of the results of energy saving measures must thus be made with due consideration to outdoor temperature variations

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54 Version April 2006 SSEIPPCBENE_Draft_1

-20 0

Energy consumption forheating MWhweek

Reduction of energyconsumption due toenergy saving measures

Weekly average outdoortemperature (degC)

Figure 216 Energy consumption depending on outdoor temperature

There are apparent similarities between the diagrams in Figure 214 and Figure 216 The output value is the production of steel and the provision of a comfortable indoor temperature respectively In both cases the operator of the system has no control of the most important parameters customersrsquo purchasing of steel products and the outdoor temperature respectively

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3 ENERGY MANAGEMENT IN INDUSTRIAL INSTALLATIONS [6 Cefic 2005] [9 Bolder 2003] [89 European Commission 2004] [92 Motiva Oy 2005] [96 Honskus 2006] [108 Intelligent Energy - Europe 2005] This chapter deals with energy management in industrial installations in broad terms It explains why good structured management is important and which issues will be considered and taken into account in a good systemstructure It covers the elements which are crucial to manage energy issues efficiently both from an environmental and economic point of view It gives examples of good management structures approaches audits methodologies and other tools which could be implemented to improve energy efficiency Detailed descriptions of the tools is in the Section 32 dealing with methodologies Systematic and transparent ways to deal with energy issues are essential to reach the best environmental and economic results Energy is as any other valuable raw material resource required to run a business ndash not a mere overhead and part of business maintenance Energy has costs and environmental impacts and need to be managed well in order to increase the businessrsquo profitability and competitiveness and to mitigate the seriousness of these impacts All industrial companies can save energy by applying the same sound management principles and techniques they use elsewhere in the business for key resources such as raw material and labour as well as for environment and health and safety These management practices include full managerial accountability for energy use The management of energy consumption and costs eliminates waste and brings in ongoing cumulative savings

31 The structure and the content of energy management 311 General features and factors Energy management means structured attention to energy with the objective of continuously reducing energy consumption and improving efficiency in production and utilities and sustaining the achieved improvements Energy management is a useful instrument to improve the efficiency of energy systems both at company and site level It provides a structure and a basis for the determination of the current energy efficiency defining possibilities for improvement and ensuring continuous improvement All effective energy (and environmental) management standards programmes and guides contain the notion of continuous improvement meaning that energy management is a process not a project which eventually comes to an end Energy management does not only focus on technical possibilities (such as the installation of a special technique) but also takes into consideration the organisation the motivation of employees good practices and the co-operation of different departments and costs Very often energy management (energy issues) is an integral part of an environmental management system or other management system Energy management can be carried out at different levels which is expressed in following bull lsquolightrsquo energy management which could be described as lsquomanagement by intuitionrsquo bull energy conservation plans (ECP) based on the plan-do-check-act cycle (see Figure 31) of

continuous improvement bull energy management based on national standards (such as the Danish DS 2403 IR and SE)

or international guidelines (international standards or guidelines on energy management) However the company may not seek certification

bull energy management following a specific standard (and certified)

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56 Version April 2006 SSEIPPCBENE_Draft_1

Table 31 illustrates different levels of energy management in more detail It should be noticed that level 4 shows the best performance

Level Energy policy Organising Motivation Information systems

Marketing Investment

4 Energy policy action plans and regular reviews have the commitment of top management as part of an environmental strategy

Energy management fully integrated into managementstructure Clear delegation of responsibility for energy consumption

Formal and informal channels of communication regularly exploited by energy manager and energy staff at all levels

Comprehensive system sets targets monitors consumption identifies faults quantifies savings and provides budget tracking

Marketing the value of energy efficiency and the performance of energy management both within the organisation and outside

Positive discrimination in favour of lsquogreenrsquoschemes with detailed investment appraisal of all new-build and refurbishment opportunities

3 Formal energy policy but no active commitment from top management

Energy manager accountable to energy committee representing all users chaired by a member of the managing board

Energy committee used as main channel together with direct contact with major users

MampT reports for individual premises based on sub-metering but savings not reported effectively to users

Programme of staff awareness and regular publicity campaigns

Same payback criteria employed as for all other investment

2 Unadoptedenergy policy set by energy manager or departmental manager

Energy manager in post reporting to ad-hoc committee but line management and authority are unclear

Contact with major users through ad -hoc committee chaired by senior departmental manager

Monitoring and targeting reports based on supply meter data Energy unit has ad-hoc involvement in budget setting

Some ad -hoc staff awareness training

Investment using short term payback criteria only

1 An unwritten set of guidelines

Energy management is the part -time responsibility of someone with limited authority or influence

Informal contacts between engineer and a few users

Cost reporting based on invoice data Engineer compiles reports for internal use within technical department

Informal contacts used to promote energy efficiency

Only low cost measures taken

0 No explicit policy No energy management or any formal delegation of responsibility for energyconsumption

No contact with users

No information system No accounting for energy consumption

No promotion of energy efficiency

No investment in increasing energy efficiency in premises

MampT ndash monitoring and targeting

Table 31 Energy management matrix [107 Good Practice Guide 2004]

To illustrate the process thinking different models have been developed but one of the most commonly used is the plan-do-check-act (PDCA) 1 cycle (see Figure 31) The PDCA cycle is often known by company management from other contexts but energy This approach is also in line with the most commonly used management approaches and standards that are relevant to industry The PDCA cycle provides a framework for the continuous improvement of a process or system The cycle is designed as a dynamic model where the completion of one turn of the cycle flows into the beginning of the next

1 The PDCA Cycle was developed by Walter Shewhart the pioneering statistician who developed statistical process control in the Bell Laboratories in the US during the 1930s Therefore it is also often referred to as lsquothe Shewhart Cyclersquo It was taken up and promoted very effectively from the 1950s on by a famous quality management authority W Edwards Deming and is consequently known by many as lsquothe Deming Wheelrsquo

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ACT PLAN

CHECK DO

Figure 31 The plan-do-check-act-cycle (PDCA) [108 Intelligent Energy - Europe 2005]

Usually good energy management practices are based on a standard or a specification which is derived from something which is already known in particular the ISO 9001 management standard and the related environmental energy management standard ISO 14001 or EMAS An increasingly popular approach are also specific energy management standards which have been developed in three EU countries (DK SE and IE) and which (as a standard or as guidelines) are also planned by the CENCENELEC Successful implementation of energy management requires commitment by the company management conducting an energy audit analysis and target setting for example by making an energy conservation plan executing the actions needed to fulfil the targets setting up a monitoringmeasuring system motivating staff and having management reviews Finally it is necessary to implement the energy management system or a corresponding structure throughout the company on a permanent basis to ensure the continuous follow-up and improvement of energy efficiency Figure 32 illustrates the continuous improvement of an energy management system

Plan ndashgt Do ndashgt Check ndashgt Act approach

5 Management review (improve) (ACT)bull Management reportingbull Deviation reportsbull Review of Targets

4 Control and corrective actions (monitor) (CHECK)bull Control of deviations + corrective actionsbull Internal and external system auditbull Benchmarking

1 Energy policy (commitment)bull Legislation LTAbull Targets CO2 or energy efficiencybull BAT LCA LCC

2 PLANbull Targets and plan of action (ECP)bull EM system standards design

3 Implementation and operation (DO)bull Organisation and responsibilitiesbull Motivating awards trainingbull Energy monitoring and reportingbull Energy purchase reporting of LTA

Figure 32 Continuous improvement of an energy management system [92 Motiva Oy 2005]

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58 Version April 2006 SSEIPPCBENE_Draft_1

Energy management can be used in all companies because it provides a general approach and structure that offers flexibility to accommodate any specific branch of business With respect to corporate management this may be understood as being either the management of the holding company or of a business unit or of a site In the following sections a good environmental structure is dealt with on the basis of a management system It expresses what items a good energy management system includes A good energy management structure is based on PDCA cycle and contains corporate commitment planning and implementing of the structure to manage energy issues concrete measures tools and resources and monitoring both technical and management commitments

312 Commitment of the top management Top management commitment is the precondition for successful energy management If energy efficiency is high on the company agenda the necessary driving forces are created for the organisation Long range visions must be defined by top management In addition the corporate management needs to communicate the commitment of resources ndash people and financial - towards this vision This commitment enables the build-up of the necessary organisational structure and some benefits are bull make it clear to the staff that energy efficiency is to be taken seriously and will give it a

higher status bull organisationally this gives the company a platform where energy problems crosscutting

various departments can be solved bull investment decisions can be taken at the appropriate level bull prevents decline in attention to energy efficiency This commitment also needs to be visible and agreed at the highest levels in the company The vision needs to be clear and visible to all employees This includes reviews of progress by high level management of the company Reviews are part of the PDCA cycle Top management also needs to help initiate an organisational structure that can work towards the goal in an efficient productive manner A culture needs to be created and demonstrated that keeps the energy topic an everyday topic This means that enough resources are allocated and good practices are implemented and kept going If the company has included energy issues in its environmental management system (or other management system) the commitment of top management is always there and is included in company energy policy As much as possible existing structures should be used although new structures can also be considered If the company has a certified (ISO EMAS) environmental management system this will automatically include the continuous improvement approach

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SSEIPPCBENE_Draft_1 Version April 2006 59

The following bullets list success factors that motivate top management to carry out energy management bull participation in a well designed long-term agreement can be a good driver to work on

energy efficiency bull need to gain competitiveness by reducing production costs as the competition in the

European markets is increasing bull increasing energy prices are a driving force bull new investments in industry enhance the penetration of new technologies in the market

As a rule new technologies are more energy efficient bull in some countries new legislation and regulations are preconditions for improving energy

efficiency bull liberalised energy markets with new emerging energy services as well as public promotion

of cogeneration and renewable energies create new opportunities for effective energy management

313 Planning To implement the top management commitment which is included in companycorporation energy policy in practice in order to achieve results in energy efficiency the company has to start and continue to do proper planning A company needs to know where is it and what it is working towards A clear measurable and traceable common goal with a timeline and defined improvement steps is the first step on the road to implementation When deciding on a definition for the timeline and the improvement steps it is important that all relevant employees co-operate and work as a team The work starts by doing the initial energy audit and continues by deciding on targets measures and resources The following list of success factors for good energy management is identified bull case studies of good practices are helpful bull work in a methodical way do not implement measures in a random way

3131 Initial energy audit Essential for this first step is the inventory of actual status (absolute energy consumption flow of energies consumers energy accounting system) versus a reference (eg competition thermodynamic targets best available techniques trends over time) With the help of this information and the company vision the energy goals can be developed The tools and methodologies for inventories are dealt with in detail in Section 32 The target of the initial energy audit is to identify a companyrsquos energy consumptions and find measures to decrease the consumption Based on this information the company can prioritise and decide on efficiency goals In the audit relevant action areas for improvement and energy efficiency opportunities can be identified

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60 Version April 2006 SSEIPPCBENE_Draft_1

The initial energy audit contains the following items bull the identification of areas or activities with significant energy consumptions bull the collection and analysis of energy consumption data bull the identification of energy efficiency opportunities bull the identification of legal and other requirements bull the determination of baseline energy consumptions bull the identification of appropriate energy efficiency indicators bull the identification of practices related to energy issues bull identification with legal and other requirements to which the company subscribes and are

applicable to the energy aspects of its activities bull the documentation of the energy audit and its revisions Different types of audits are dealt with in Section 321

3132 Energy performance targets To set up performance targets and thestructure to implement those is a key issue in improving energy efficiency in a company The performance targets will be set for processes and other activities which have significant energy consumption and conservation potential and are related with legal or other rules and requirements It is important to understand the character of the individual business units to improve their energy efficiency On the other hand only an understanding of the interrelation of these units will guarantee the overall best results bull goal setting needs to take into account the other units on the site and even in the local

environment bull the definition of plans and distribution of resources needs to bear in mind the corporate

network conditions bull waste from one unit can be valorised as an energy carrier in another unit The energy performance targets are clearly defined and measurable They are documented and there is a time frame for their achievement Energy management achievements are monitored and benchmarked systematically The company also sets and revises its energy performance targets systematically according to bull the energy consumption significance bull the relevant legal aspects bull the companyrsquos current technological operational and financial capacity The energy performance targets are appropriate for benchmarking and consistent with the energy policy Appropriate indicators are very important for understanding the current situation and also for checking progress versus goals Thus all necessary data need to be collected stored and communicated constantly and consistently to calculate these indicators For finding measures to improve energy efficiency there are different tools like Pinch methodology audits etc These are dealt with in more detail in Section 32

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Continuous improvement is an essential element to drive energy efficiency Good energy management needs to follow the plan-do-check-act cycle which should be included in all management systems It guarantees that task and responsibilities are defined and progress is checked on a regular basis When operating within this cycle the actual performance is compared to planned performance Depending on results of this cycle further measures and tasks need to be defined or redefined

3133 Action plan The company will establish and maintain an action plan for achieving its energy performance targets and the realisation of the energy policy The action plan will include bull actions for the achievement of the energy targets bull the means and resources for each action bull designation of responsibility for each action bull determination of the time frame for each action bull deciding the indicators bull means to monitor indicators and targets The action plan is consistent with the companyrsquos energy policy and its current technical financial and operational capacity

314 Doing To achieve the goals it is necessary to have a proper action plan and a focused organisation Existing structures (like qualityenvironmental management) or it can be helpful to develop a new (independent) structure The tools that are used to drive energy efficiency can be energy specific like Pinch methodology energy audits and studies or come from general management toolsets which are either externally or internally developed The following list of success factors for good energy management is identified bull guide the company step-by-step through the implementation of energy management is

useful Energy advisors and other helpdesks are instrumental in this process Practical action-specific programmes are better than generic support and guidance

bull give the company access to tools that are easy to use for example o checklist for the level of energy management o tools for the implementation of energy management o tools for dailymonthlyyearly energy monitoring o reporting modules (eg for the competent authorities)

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3141 Structures and responsibilities The structures will allow for implementation and control of all aspects of the action plan like technical measures training of employees improvement of internal procedures communication and tracking The company will define and document roles and responsibilities of the staff and then communicate them in order to facilitate effective energy management Furthermore top management will provide resources essential to the implementation and control of the energy management systemstructure eg resources include human resources specialised skills technology and financial resources It will be beneficial to appoint an Energy Manager who irrespective of other responsibilities will have defined roles responsibilities and authority for bull the continuous improvement of the companyrsquos energy performance bull the implementation of the energy management system bull the monitoring benchmarking and reporting of the energy performance bull the staff involvement in the effort for energy performance improvement The company should assign responsibilities according to function level education experience personality and capability in order to achieve efficient implementation of the energy management system

3142 Awareness raising and capacity building The best energy efficiency cannot be achieved only by technological measures but also good practices and staff involvement are needed Benefits of investments may even be destroyed if human resources are not included and motivated It is crucial that staff are trained The company will communicate energy policy to all the personnel in order to inform and encourage personnel to contribute to energy performance improvement The company will inform its personnel about the following energy related issues bull the importance of energy efficiency to the company bull the companyrsquos efforts towards energy efficiency bull the consequences of their work activities in energy consumption bull their roles and responsibilities in the effort towards energy efficiency The company will identify the key personnel whose work significantly affects energy performance and specific training should be organised for these people in order for them to be efficient in energy management Appropriate training activities should be planned and carried out

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3143 Communication and motivation Communication and motivation are crucial tools so that modern companies can implement all kinds of issues Communication is a key element because it provides feedback to all partners about their performance Communication is used positively to provide recognition of achievers Communication includes bull inside an individual company all staff should be involved bull involving several companies from the same sector in a working group (energy networking)

to exchange experiences has proven useful The companies should all be at the same level of energy management implementation Networking is especially useful for solving typical difficulties such as defining an energy efficiency index or setting up an energy monitoring system Networking may also introduce an element of competition in energy efficiency and provide a platform for negotiation with potential energy efficient equipment or service suppliers

bull positive effects should be made clearly visible Awards for best practices are a possibility to implement this

Well structured communication secures the flow of information of goalscommitments as well as the achieved results The company will implement practices that ensure efficient two-way internal communication concerning the effort towards energy efficiency The company will also inform its staff about energy efficiency and systematically support encourage and motivate them to contribute to energy efficiency by conserving energy preventing unnecessary consumption working efficiently and making recommendations and observations Communication is also used to encourage the exchange of information with other companies - to swap best practice ideas and to pass success stories from one company to another etc The possible means of communication are a system of specific energy consumption numbers (daily weekly monthly yearly) over time or in correlation with important parameters (like production rate weather conditions) combined with success stories in periodically published reports Graphics are an excellent way to provide information

315 Checking The company cannot demonstrate its energy efficiency and improve its energy performance if it is not monitoring and measuring its energy flows and other important indicators This enables feedback to the management on the effectiveness of energy efficiency measures Take care that those responsible for energy efficiency have the ability to control it This means that good monitoring (lsquoif you canrsquot measure it you canrsquot manage itrsquo) and reporting are essential

3151 Monitoring and measurement Monitoring is an important element of the PDCA cycle and a prerequisite for demonstration of efficient energy use and benchmarking Monitoring is planned together with energy efficiency indicators

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64 Version April 2006 SSEIPPCBENE_Draft_1

A company will systematically measure and monitor its energy flows and other relevant factors which have been identified as crucial to follow Tools for monitoring are dealt with in Section 32 Appropriate energy indicators (see Section 22) are periodically calculated registered analysed and reported A company will evaluate its energy performance according to its energy targets Actions and practices will be amended for the achievement of energy targets whenever necessary A company will have practices to detect and investigate non-conformances that significantly affect its energy efficiency and will respond to them in order to minimise their negative impacts Monitoring will be dealt with in more detail in Section 322 Information will be collected via an energy information system which will also analyse and report the results

3152 Records The company will keep records of its energy performance that are tailored to their energy management system requirements Records should be legible identifiable accessible and traceable to the relevant process activity or person

3153 Periodic energy audits In addition to initial energy audits the company will periodically perform different energy audits in order to bull determine its current energy performance bull check the systemrsquos implementation and maintenance bull compare results with system targets bull provide benchmarking information bull investigate problems and identify causes and weaknesses bull inform the management of the company bull find new measures to improve energy efficiency Energy audits are dealt with in Section 321

316 Acting The companyrsquos top management will periodically review the energy management system and the results to ensure its continuing suitability adequacy and effectiveness and to evaluate its performance via benchmarking The review process will ensure that the necessary information is collected to allow management perform this evaluation The management review will address the possible need for changes to energy management policy objectives and practices in the light of energy audits results changing conditions and the commitment to continual improvement of the companyrsquos energy performance

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317 Examples of energy management systems and its implementation No information provided We expect to include here real examples of application of energy management systems in different industrial sectors and companies This also includes bull all steps in the management cycle bull data of energy efficiency improvements bull economic data

32 Methodologies and tools for energy use optimisation and energy efficiency

This section describes the tools which have been developed to support energy management The following list shows various tools which have been identified and which are described in more detail in the succeeding sections bull energy audits bull energy monitoring bull energy models bull pinch methodology bull benchmarking bull e-learning bull checklists bull good housekeeping The different tools are described in a relevant and suitable way in every case

321 Energy audits [92 Motiva Oy 2005] [40 Meireles 2005] [31 Despretz ] [7 Lytras 2005] The term lsquoenergy auditrsquo is in principle well known and commonly used What is actually meant by the term in individual cases can in practise include an extremely wide range of different applications The variety within the family of energy audits should be understood as should the importance of also defining the the scope content and depth of the audit in more detail Audits are crucial tools in energy management Different types of audits (technical audit best practice audits management audits) may be used in different phases and four different purposes during the implementation of energy management systems An energy audit is a systematic analysis of energy usage which identifies the main areas operations and types of energy used in a unitprocesssite It may also identify the cost effective energy saving opportunities and report the findings

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3211 Audit models In most cases energy audit is one module among other energy efficiency activities Figure 33 shows the basic energy audit models

THE SCANNINGMODELS

THE ANALYSINGMODELS

The walk throughenergy audit

The preliminaryenergy audit

The selectiveenergy audit

The targetedenergy audit

The comprehensiveenergy audit

MAG

NIT

UD

E

AC

CU

RA

CY

VERTICAL HO

RIZ

ON

TAL

The systemSpecific Energy

Audit

Figure 33 Basic energy auditing models [92 Motiva Oy 2005]

An audit model is usually a standardised commonly known and commonly followed procedure with written guidelines The requirements are usually defined in the guidelinesstandards given by company itself or by the standardisation body An energy audit may cover a site or a building in various ways ndash the scope of audits may be different At the lsquonarrowestrsquo an energy audit covers typically only one specific system (or a process) and at the lsquowidestrsquo an energy audit covers everything inside the site fence Between these lsquonarrow and wide endsrsquo there are energy audits that deliberately ignore some areas or issues In most audits related to the implementation of standards there are clear requirements as to what audits should include Energy audits are used for different purposes either for pointing out the areas where savings can be made or for describing in detail the actual saving measures so that they can be easily implemented These properties of energy audit models are illustrated in Figure 34

NARROW WIDE

ROUGH COMB FINE COMB

TO POINT OUT TO PROPOSE

THE SCOPE

THE THOROUGHNESS

THE AIM

Every systemall sites

Detailed potentialassessment

Specific energysaving measures

Specific systemarea

General potentialassessment

General energysaving areas

Figure 34 The properties of energy audit models [7 Lytras 2005]

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SSEIPPCBENE_Draft_1 Version April 2006 67

This section presents the different energy audit models divided into two main classes according to their aim to the scanning energy audit models and to the analysing energy audit models (see Sections 32111 and 32112) Within these two classes the different models have been specified according to their scope and thoroughness The basic energy audit models are not used very often as such and therefore the models in actual use are different types basic model applications The applications have different features depending on an interface to the connected activities

32111 The scanning models The main aim of the scanning energy audit model is to point out areas where energy saving possibilities exist (or may exist) and also to point out the most obvious saving measures Scanning audits do not go deeply into the profitability of the areas pointed out or into the details of the suggested measures Before any action can be taken the areas pointed out need to be analysed further A scanning audit model is a good choice if large audit volumes need to be achieved in a short time These types of audits are usually quite cheap and quick to carry out From the companyrsquos point of view a scanning audit may not bring the expected results because it does not necessarily bring actual saving measures ready for implementation but usually suggests further analysis of key areas

Walk-through energy audit A walk-through energy audit is suitable for small and medium sized industrial sites if the production processes are not very complicated in the sense of primary and secondary energy flows A walk-through energy audit gives an overview of the energy use of the site points out the most obvious savings and also points out the needs for the next steps (supplementary lsquosecond-phasersquo audits) The walk-through energy audit has been used by ESCOs in the scanning phase of third party financing projects

Preliminary energy audit The scanning energy audit model for large sites is called the preliminary energy audit Audits of this type are typically used in the process industry Although the main aim of the preliminary energy audit is in line with the walk-through energy audit the size and type of the site requires a different approach Most of the work in the preliminary energy audit is in building up a reliable breakdown of the present total energy consumption and defining the areas of significant energy consumption and usually also of the probable energy saving measures The reporting also points out the areas where supplementary lsquosecond-phasersquo audits are needed and how they should be targeted (see Section 3131) The preliminary energy audit normally needs to be carried out by a team of experts Expertise is needed both on the auditing procedure itself as well as on the production process The preliminary energy audit always requires committed participation from the technical personnel of the site

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32112 The analysing models The analysing energy audit models produce detailed specifications for energy saving measures providing the audited client with enough information for decision-making Audits of this type are more expensive require more work and a longer time schedule but bring concrete suggestions on how to save energy From the companyrsquos point of view the saving potential can be seen and no additional surveys are needed The analysing models can be divided into two main types bull selective energy audits where the auditor is allowed to choose the main areas of interest bull targeted energy audits where the company has defined the main areas of interest

Selective energy audit The selective energy audit looks mainly for major savings and does not pay attention to minor saving measures This audit model is very cost effective when used by experienced auditors but may in the worst case be real lsquocream skimmingrsquo There is always the risk that when a few significant saving measures are found the rest will be ignored

Targeted energy audit The content of work in the targeted energy audit is specified by detailed guidelines from the company and this means that most of the systems to be covered by the targeted energy audit are known in advance The guidelines set by the Company may deliberately exclude some areas The reason for excluding certain areas may be that they are known to be normally non-cost relevant The targeted energy audit usually produces a consumption breakdown and includes detailed calculations on energy savings and investments If the guidelines are adequate the audit produces a standard report From the companyrsquos point of view the targeted energy audit is always a risk if quality control is neglected if there is no control on the auditorsrsquo work they may be tempted to slowly move towards the selective energy audit because this model always includes less work System specific energy auditAn example of the targeted energy audit at the simplest and smallest is the system specific energy audit This type of audit has a tightly limited target (one system device or process) but the thoroughness of the work is usually very high The benefit of this audit model is that it is possible to have the best expertise on the work normally better than what an average auditor can provide The system specific energy audit produces a detailed description of the system and points out all profitable saving measures with alternative options concerning the specific system One good option is to combine this kind of audit as a sub-model with some more comprehensive audit models System specific energy audits give high saving potentials compared to the energy use of the system The problem is that when looking at only one part of the site the lsquobigger picturersquo is missing and a risk of partial optimisation exists For example when only studying only energy efficiency of compressed air or cooling systems heat recovery opportunities cannot be evaluated because there is no knowledge as to where heat could be used in the most efficient way Energy systems are usually interrelated and seldom independent

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SSEIPPCBENE_Draft_1 Version April 2006 69

Comprenhensive energy audit A comprehensive energy audit is a targeted energy audit at the lsquowidestrsquo end of the scale it covers all energy usage of the site including mechanical and electrical systems process supply systems all energy using processes etc Some minor systems may be excluded but they should not really be relevant in proportion to the total energy consumption The clear difference to the targeted energy audit is that the targeted energy audit deliberately ignores some areas that are known and specified in advance and the comprehensive energy audit covers everything The starting point in this type of audit is always an analysis on the detailed breakdown of the total consumption The comprehensive energy audit comments on all systems using energy specified at the beginning - regardless if savings are found or not it points out all profitable saving measures and includes detailed calculations on energy savings and investment costs This model also creates a basis for a very standard and detailed reporting which brings some advantages to the company especially in quality control and monitoring

32113 The technical coverage of energy audit models Depending on the goals of the energy audit programme or activity the audit models can be defined to cover different aspects of the site If the main target of the programme is to achieve energy savings then all energy use should be analysed However if the main aim is to promote the use of renewable energy sources the viewpoint is slightly different The technical content of an audit model can be illustrated by a lsquobox-modelrsquo Figure 35 Figure 36 and Figure 37 give an idea of the different approaches

ENERGY PRODUCTION ON SITEENERGY PRODUCTION ON SITEBUILDING ENVELOPEBUILDING ENVELOPE

BUILDING SERVICE SYSTEMSBUILDING SERVICE SYSTEMS

PROCESS SUPPLY

PRODUCTIONPROCESSHEATING AND FUELS

WATER

ELECTRICITY

RENEWABLES

Figure 35 Coverage of an industrial site energy audit [7 Lytras 2005]

The comprehensive energy audit for an industrial site covers all energy use of process process supply systems building service systems and heat production

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70 Version April 2006 SSEIPPCBENE_Draft_1

ENERGY PRODUCTION ON SITEENERGY PRODUCTION ON SITEBUILDING ENVELOPEBUILDING ENVELOPE

BUILDING SERVICE SYSTEMSBUILDING SERVICE SYSTEMS

PROCESS SUPPLY

PRODUCTIONPROCESSHEATING AND FUELS

WATER

ELECTRICITY

RENEWABLES

Figure 36 Coverage of a district heating connected to a residential building energy audit [7 Lytras 2005]

In a district heating connected to a residential building the energy audit covers the total picture of the building service systems Electricity use by the residents is ignored

ENERGY PRODUCTION ON SITEENERGY PRODUCTION ON SITEBUILDING ENVELOPEBUILDING ENVELOPE

BUILDING SERVICE SYSTEMSBUILDING SERVICE SYSTEMS

PROCESS SUPPLY

PRODUCTIONPROCESSHEATING AND FUELS

WATER

ELECTRICITY

RENEWABLES

Figure 37 Coverage of a CHP plant energy audit [7 Lytras 2005]

In a CHP power plant energy audit the energy production process is analysed and the possibilities for using renewable are investigated

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SSEIPPCBENE_Draft_1 Version April 2006 71

3212 Audit tools Lot of tools have been developed to lsquostandardisersquo contents and approaches of audits Usually companies have tailor-made tools like checklists to use in auditing procedures The following paragraphs will describe some of the tools bull informationdocumentation on technical topics (eg ECOs1 branch specific) - this is

an information support document which is often based on case studies and intended to help in marketing the audits in view of successful examples The main target is the benefactor of the audit This document focuses on one particular technique andor a specific subsector (in the industry) and the information given is summarised mainly on results and interviews Depending on the accuracy of the information these tools can also be considered andor used as promotion support elements

bull audit guide or audit handbook energy management handbook ndash this is a core component of an energy audit scheme which is the basis of training sessions and is targeted essentially to auditors It explains and describes how an audit is to be made how the calculations are to be conducted the types and contents of the most frequently proposed energy conservation options (ECOs) Although auditors are supposed to have a fair background in thermodynamics (and also electricity) these handbooks frequently entail a section of reminders of these energy related topics

bull energy checks checklists or walk-through guides - associated with energy audit models of the scanning type these supporting documents are developed in order to facilitate the work of the auditor assuring at the same time both quality and rapidity of the survey They are primarily intended for energy auditors but can also be used as self auditing tools for those energy managers in industrial premises who intend to start an energy management process by themselves before requiring external assistance

bull calculation methods and software - another core component of energy audit schemes are calculation methods and software which are associated to energy audit models of the analysing type Their primary objective is to help the auditor in the quantitative assessment of energy saving potentials and evaluation of investment costs and paybacks The use (by an auditor) of a recommended or certified calculation tool (provided it is used correctly) is a certainty for quality results quality for the audited client

bull data collection form(s) - generally associated to the calculation tool for which they constitute the input data this type of support document helps the auditor in collecting all the necessary information for the survey It will be part of the final report and will also contribute to facilitating the follow-up of the site energy features and the interpretation of the audit results and recommendations

bull report templates - as for data collection forms report templates are also frequently associated with the calculation tool of which the output results must be integrated in the report The report is the deliverable of the audit proposing a template helps all the participants to make the most profitable use of the audit service and produce good quality audit reports

bull checklist for quality control of audit reports ndash this checklist is a document which can be used at both company level and at auditor level (self-check) it is a complement or an alternative to report templates and a practical translation of energy audit models what is specified in the energy audit model as expected results should be in the report and the checklist is an easy way to verify that the work has thus been done according to the specifications

bull building ratings target values or benchmarking - key figures can be used either as marketing information to spark off the need for energy audits they are also used by the auditors as technical data to justify their recommendations in the case of simplified audits and can even contribute to detailed audits in checking calculations or replacing data difficult to meter or evaluate either way

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72 Version April 2006 SSEIPPCBENE_Draft_1

bull databases on energy conservation options (ECOs) - one difficult part of the audit is having detailed information on costs and consequences of energy saving recommendations A database of ECOs encompassing this information will save a lot of time and money for the auditorcompany and thus help lower the cost of the audits with a maintained quality Keeping the data up-to-date requires quite a lot of work

Many of these tools may overlap and it is the responsibility of the company to determine what is necessary to use The above-mentioned tools are in general not specific of a target sector or an energy audit model but their usefulness frequently corresponds to one or several phases of the audit survey

322 Energy monitoring [55 Best practice programme 1998] [56 Best practice programme 1996] [98 Sitny 2006] Energy monitoring is the predominant activity within energy management to use and interpret energy use information The objective of monitoring is to get reliable and traceable information on the issues which influence energy efficiency (eg energy flows press-levels) Energy monitoring is a practical tool used for demonstrating that energy efficiency objectives set in energy programme for a whole company are implemented and achieved To achieve those objectives some sub-objectives or targets are set in the monitoring system Also eg material flows can be incorporated in the monitoring system Monitoring is at the heart of any strategic approach to energy management If there is no special energy management system the monitoring must be linked to other management systems Monitoring enforces the principle that energy should be viewed as a production cost rather than an overhead A monitoring system provides management information on the use of energy and other resources This information is collected by several relevant measuring points in the process and utilities and then analysed in cost accounting centres (EACs) and further at department and site level Energyenvironmental account centres are the units at the site where energy usage can be related to a production variable such as throughput The structure of the monitoring system is illustrated in Figure 38

Meters

SITELevel 1

DepartmentLevel 2

DepartmentLevel 2

Account centreLevel 3

Account centreLevel 3

Account centreLevel 3

Account centreLevel 3

Figure 38 Structure of a monitoring system [98 Sitny 2006]

This monitoring process is continued on a regular basis and the information is collected in the form of reports on performance against targets Regular reviews of these reports improve awareness of resource consumption and highlight areas where efficiency can be improved as shown in Figure 39

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SSEIPPCBENE_Draft_1 Version April 2006 73

Measure energy consumptionand production

Review performanceand action plan

Implement energysaving measure

Develop targets

Produce reports to monitor energy use

against output

Figure 39 Monitoring process [98 Sitny 2006]

The principle of this monitoring is a universal methodology and so not limited to a specific sector Therefore the approach can be used for virtually all sectors eg for the food and drink industry metal industry chemical industry buildings and transport but the degree of complexity varies An operating monitoring system consists of six major steps These are bull metering metering energy usage through a system of sub-meters to identifiable areas or

individual pieces of plants eg named as energy account centres (EACs) The most common intervals are weekly daily or shifts Monthly invoices from utilities are generally not sufficient

bull targeting determining target levels for each of the EACs by relating the energy usage to a measure of activity eg the output of the production line in a factory or outside temperature

bull analysis establishing a regular reporting system in most cases weekly that gives a performance measure for each EAC and identifies variances in terms of financial gain or loss A variance prompts an analysis maybe including further investigation and then an action

bull accountability to make people responsible is a powerful way of ensuring their commitment bull energy teams setting up energy teams that meet regularly to discuss ways of improving

performance and to carry out the actions identified In addition a regular feedback mechanism on performance to all levels of the company creates greater awareness and the motivation to improve

bull action taking action to reduce waste of energy The monitoring system reveals energy losses and all those involved must make decisions to implement the measures to improve the situation Monitoring helps to identify problems and then the correct action can be taken Action is essential for achieving savings

323 Energy models [11 Franco 2005] A very basic issue for improving energy efficiency is to know the starting point In many cases there are not proper measurements and so the information even from the use of energy is very vague To improve the situation a measurement system must be set up Usually an energy audit is needed and based on that information will be gathered

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Energy models are useful tools to carry out complete and in-depth energy diagnoses in whatever context (industrial service buildings) The aim of an energy diagnosis is to identify and select a number of actions that once implemented reduce the cost of the supplied energy It is possible to reach such an aim by bull rationalising important energy streams bull identifying ad-hoc energy saving technologies bull recovering waste energy streams bull optimising energy supplying contracts Each of the above goals has to be focused on two aspects one technical and the other economic however only the technical aspect is described here The technical aspect both under a theoretical andor experimental point of view concerns knowledge of productive plants and services Such knowledge has to be formalised so that it can be easily managed The first tool to fix the technical knowledge about plants is an energy model The model both electric and thermal summarises all the energy consumptions in the studied context in the form of a data sheet A reliable energy model is the primary tool one can face the energy question with It should be complete but not redundant easy to write out handy to consult useful for the heads of different departments such as energy management maintenance purchasing and accounts An energy model is based upon data collected lsquoin the fieldrsquo or after hypothesis and evaluations It is preferable if the data are collected and classified as follows bull department or production line bull utilities (compressed air pumping vacuum external lighting etc)

3231 Example 1 Electric energy models For the electric model at least the following data for each working device needing electricity such as motors and drives pumps compressors electric furnaces etc are gathered bull rated power bull rated efficiency bull load factor bull working hours per year Whereas power and efficiency are easy to detect as they are normally labelled on the device itself the load factor and the hours per year is estimated When the load factor is estimated to be greater than 50 then the load factor itself is approximately equal to

P(eff) LF= P(rated) x ŋ Equation 31

where bull LF is the load factor bull P(eff) is the estimated average electric power effectively absorbed by the device during its

working hours (kW) bull P(rated) is the rated power (kW) bull Ŋ is the rated efficiency of the device (at full load)

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If necessary Peff can easily be measured by some electric power meters It must be pointed out that the efficiency and the power factor of a device depend on the load factor according to Figure 310 drawn in this case for a generic motor

Efficiency

Power factor

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100Load factor ()

Figure 310 Power factor of a device depending on the load factor [11 Franco 2005]

If the single case must be handled attentively eg because of the dimensions of the machinery or its importance in the process then the auditor must calculate the real efficiency by means of a specific diagram for a specific device Once the real efficiency has been determined then this correct value should be used in Equation 31 The contect of a simple electric model is illustrated in Table 32

A B C D E F G

DEPARTMENTS DEVICES n Rated power

kW

Rated efficiency

Working hours per

year

Load factor

Energy consumed

kWh

Department 1 Device 1 10 55 092 500 1 298913

Device 2 20 4 085 4000 08 301176

Device 3 15 10 09 4000 09 600000

Total Dept1 780 1200089 175

Department 2 Device 1 1 500 085 3500 05 1029411

Device 2 20 15 09 4000 1 1333333

Device 3 5 75 08 4500 09 189844

Device 4 10 2 075 1500 08 32000

Device 5 3 150 092 3000 095 1394022

Total Dept 2 1307 3978611 581

Department Device hellip hellip hellip hellip hellip hellip

TOTALS 3250 5425000 1000

Table 32 A simple electric model lsquonrsquo in column lsquoArsquo represents the number of identical devices (under both a technical and an operating point of view) present in that department

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76 Version April 2006 SSEIPPCBENE_Draft_1

The lsquoenergy consumedrsquo in column lsquoFrsquo is given by multiplying the number of devices x rated power x working hours x load factor and dividing by rated efficiency

A x B x D x EF= C Equation 32

By adding all energies consumed in each department the total energy consumed by the entire plant can be calculated If the context studied is not so broad or complex this kind of model could be adequate to detect the areas where energy saving possibilities are most likely to be found It is sufficient to direct attention to the distribution of electricity consumptions for each department shown in column lsquoGrsquo It is very likely that a series of actions to improve energy efficiency will be found in those departments where consumption of energy is the highest while departments whose consumption is low can be neglected or taken into account later When the context deserves it (because the cycle of production is extremely complex or when energy data have never been collected before) it would also be useful to collect following data to identify energy saving actions eg bull for motors and drives

o kind of machinery driven by the motor (compressor fan pump etc) o identification code o manufacturer and model name o type of motor o installation year or residual life o number of rewinds carried out so far o type of speed control if existing o type of mechanical transmission o possibility to shift the operation to different times (to exploit more favourable electricity

tariffs at specific times or on specific days) bull for lighting apparatus

o type of lighting body o number of lamps in a body o number of lighting bodies o type of lamps o rated power of the lamp o efficiency of the lamp o kind of ballast (iron copper or high frequency)

Validation Since a good energy model is a strategic tool to carry out an energy audit it is mandatory to validate it before use The first step to validate an energy model is to compare the total amount of energy consumed as derived from calculations with the amount consumed as shown in the invoices for energy supplies If the context is very broad or complex it would be useful to compare partial amounts of energy consumed in each department with the amounts locally recorded by some automatic accounting device

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If there is not a good correspondence between the two amounts of energy (coming from the energy model and from invoices) this means that the hypothesis assumed at the beginning to draw up the energy model must be modified In particular the load factors and the working hours for the different devices must be determined with greater accuracy Another cause for non correspondence is the failure to take into account all devices really working in the plant

3232 Example 2 Thermal energy models The drawing up of a thermal energy model is more complex than an electric model To have an exact and reliable picture of the thermal consumption two kinds of models are compiled first level models and second level models To compile the first level energy model it is necessary to take a census of all users of any kind of fuel For any consumer of fuel (eg boilers furnaces etc) the following data should be recorded bull kind of fuel supplied quantity in a year bull kind of thermal carrier entering the boiler (eg pressurised water) flowrate temperature

pressure bull condensate percentage of recovery temperature pressure bull boiler body manufacturer model installation year thermal power rated efficiency

exchange surface area number of working hours in a year body temperature average load factor

bull burner manufacturer model installation year thermal power bull exhaust flowrate temperature average carbon dioxide content bull kind of thermal carrier leaving the boiler (eg steam) temperature pressure Though all previous data should be collected in the first level thermal model (lsquogeneratorsrsquo sidersquo) only a few of them must be taken into account as in the drawing of an electric model (see Table 33)

A B C D E F G

PROCESS Device n Rated power kWth

Rated efficiency

Working hours per

year

Load factor

Energy consumed Nm3 CH4

Big kilns 4 800 085 7700 08 2417000 Phase 1 (eg burning) Small

kilns 5 600 085 7700 08 2266000

Total Phase 1 6200 4683000 765

Hot water boiler 2 2500 092 1000 05 283200

Steam boiler 2 1000 092 7000 05 793200

Phase 2 (eg heat production) Hot water

boiler 2 1000 092 1600 05 181200

Total Phase 2 9000 1257600 205

Spray drier 1 400 07 200 1 11900 hellip Hot air generator 1 400 085 1600 05 39200

Small heaters 37 30 08 1600 05 115700

Phase 3 (eg Services)

Big heaters 2 60 08 1600 05 12500 30 Total Phase 3 2030 179300

TOTALS 3250 6119900 1000

Table 33 Data ina thermal energy model (generators side)

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78 Version April 2006 SSEIPPCBENE_Draft_1

In this case to make the comparison easier the energy consumed has been estimated as Nm3 of natural gas The amounts of natural gas consumed are given in this case by

A x B x D x E x 3600F= C x 34500 Equation 33

Where 1 3600 conversion factor from kWh to kJ 2 34500 is the net heating value for natural gas (kJNm3) The first level thermal model (lsquogeneratorsrsquo sidersquo) must be checked to see if the total amount of energy demand is equal to the total energy reported in the invoices for natural gas supply If so the model is reliable and useful to indicate the best areas in which to implement energy saving actions When assessing the thermal use of energy second level models (lsquousersrsquo sidersquo) are also required to be built To draw up such data sheets it is necessary to take a census of all machineries needing thermal energy in any form (hot water steam hot air etc) except fuel (taken into account in the first level model) For every item of machinery the following data should be collected bull kind of thermal carrier needed bull hoursyear of thermal demand bull load factor at which thermal energy is used bull rated thermal power

Such data can be arranged in Table 34 as follows

A B C D E F G

DEPARTMENTS DEVICES n Thermal carrier

Thermal power kWth

Working hours

per year

Load factor

Energy request

Nm3 CH4

Department 1 Device 1 2 steam 500 1000 1 104200

Device 2 1 steam 125 500 08 5200

Device 3 5 hot water 75 5000 08 156400 Total Dept 1 265800 218

Department 2 Device 1 1 steam 75 2500 05 9800

Device 2 20 hot air 10 3000 1 62500

Device 3 5 steam 50 2500 08 52100

Device 4 10 hot water 5 1500 08 6300

Device 5 3 steam 25 3000 09 21100 Total Dept 2 151800 125

Department Device

TOTALS 1215700 1000

Table 34 Data in a thermal energy model (users side)

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SSEIPPCBENE_Draft_1 Version April 2006 79

The second level model (lsquousersrsquo sidersquo) is useful to verify the match between the heat supplied by the utilities (boilers heat generators etchellip) and the heat requested by the users In this case the amounts in column F are given by

A x C x D x E x 3600F= 34500 Equation 34

In the previous example the calculation was as follows 1257600 + 179300 = 1436900 Nm3 of natural gas supplied In the second level model the calculation shows 1215700 Nm3 of natural gas demand The 15 difference is due to the efficiencies at following steps heat generation distribution piping and regulation and final use If this difference is acceptable then the two models can be considered as lsquocertifiedrsquo in the opposite case some correction (normally to the number of working hours or the load factors) is needed to reach convergence If the difference between the two amounts is big this is due to a high level of losses in the production-distribution-use for different carriers (eg steam hot water etc) In this case different actions aiming to improve the energy efficiencies for example in the field of insulations of recovery of condensate etc are likely to be possible

3233 Energy diagnosis using the energy models A complete energy diagnosis for a given organisation can be carried out according to Figure 311

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80 Version April 2006 SSEIPPCBENE_Draft_1

1) Process analysis

2) Drawing up ofenergy models

3) Theoretical energyindicators

6) Effective energyindicators

4) Energy invoicescollection

7) Areindicators

comparable

9) Areindicators

comparable

8) Reference energyindicators

10) Detecting energysaving actions

11) Cost-benefitanalysis

12) Priority foreconomically viable

actions only13) End of diagnosis

5) Production datacollection

NO

YES

YES

NO

Figure 311 Scheme of energy diagnosis [11 Franco 2005]

Notes bull points 1) 2) 3) are the collection of energy data coming from the electric and thermal models and the

calculation of appropriate energy indicators (eg MJtonne of product kWhm2 etc) bull the same indicators must be calculated from the data of production and for energy supplies points 4)

5) 6) bull such indicators are compared (7) and if they are almost equal then the energy models can be

considered lsquocertifiedrsquo otherwise corrections have to be made to the models themselves until convergence is reached

bull the lsquocertifiedrsquo indicators have now to be compared with energy benchmarks coming from literature energy agencies scientific associations etc If this kind of indicator is still comparable then it means that the lsquoenergy behaviourrsquo of the organisation is in the mainstream average and that it will be difficult to find corrective actions

bull finally if the certified indicators are greater than the benchmarks then energy use in the organisation can be improved It is likely that some energy saving actions will be detected and once only those viable from an economic point of view have been implemented the energy indicators will converge and at this stage the diagnosis can be considered finished

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SSEIPPCBENE_Draft_1 Version April 2006 81

324 Pinch methodology Description of the energy efficiency technique Pinch methodology is a process integration methodology which provides several tools in order to analyse industrial processes in terms of energy saving and pollution prevention according to costbenefits assessment Pinch is a computer-based simulation tool to analyse the minimum energy targets of industrial plants The analysis will identify realistic energy saving projects The starting point is the analysis of involved streams (hot and cold) and utilities (eg fuel steam cooling water) and then the creation of composite curves Each process stream can be represented by a curve in the enthalpytemperature plot moving from the hot temperature to the cold temperature with a fixed heat capacity (CP) All the hot streams could be represented by the hot composite curve obtained by the sum of heat capacity flowrates of streams that are presents in each temperature interval The hot composite curve represents the energy accumulated in the process streams and the temperature range in which it is available Similarly all the cold streams are represented by the cold composite curve The composite curves are plotted in the same HT plot to provide information about the system (see Figure 312) these information are bull minimum process heat required from hot utilities QHmin bull minimum process heat released to cold utilities QCmin bull heat recovery

Hot composite curve

∆∆TTminmin

Cold composite curve

PINCH

QHmin

QCmin Heat recovery

H

T

Figure 312 Hot and cold streams in Pinch methodology [12 Pini 2005]

These are the energy targets for the process From this evaluation it is possible to perform a complete pinch methodology study aimed at identify how these targets could be achieved Heat recovery and integration opportunities are analysed by studying how hot material streams can heat and cold material streams cool the process flows

Chapter 3

82 Version April 2006 SSEIPPCBENE_Draft_1

One of the most important features of this procedure is the template creation The templates are Excel files where the input and output data describing the industrial processes are presented The creation of these files allows us to manipulate the data in effective way so that local operating conditions at other sites can be accurately represented For example the template created for crude distillation unit of a refinery if rightly manipulated should be suitable for describe another similar CDU Pinch methodology has usually the following steps

Steps Main features

Data acquisition PFD Process stream data Utility data

Simulation Template for providing utility and process data

Pinch methodology

Utility assesment (grand composite curve) Minimum energy consumption valuation

Saving calculation Template

Economic aspects Template

Table 35 Steps in Pinch methodology

Achieved environmental benefits especially including improvements in energy efficiency The procedure fits the energy efficiency concept well because it allows the minimum energy consumption of a plant and the subsequent potential saving to be quantified Moreover pinch methodology offers the tools to understand the way the energy savings can be obtained Quite often process industry uses from 10 to 30 extra energy compared to the best design solutions This methodology reduces energy consumption and variable cost of the unit and the CO2 emissions can be reduced to 10 ndash 30

Operational data Some results of the application of pinch methodology are shown in Figure 313 Refinery (nominal capacity is 4550000 tonnesyr) composed of following sections bull primary distillation (DP3) bull catalytic reforming (RC3) bull liquid petroleum gas (LPG) splitter bull isomerisation (ISO) bull dewaxing and hydrodesulphuration (MDDW+HF1) bull visbreaking and thermal cracking (VBampTC) bull merox unit bull sour water stripper (SW1) bull naphta splitting

Chapter 3

SSEIPPCBENE_Draft_1 Version April 2006 83

Olefins and aromatics production (nominal feed is 490000 tonnesyr of virgin naphtha) It is a traditional steam cracking TDI plant (118000 tonnesyr) where toluene diisocyanate is produced via phosgene Olefinic products besides ethylene are propylene cracking gasoline and residuum Aromatic products (benzene toluene dicyclopentadiene) are recovered from cracking gasoline A TDI plant (11800 tonnesyr) is where toluene diisocyanate is produced via phosgene Vinyl chloride monomer (VCM) and polyvinyl chloride (PVC) production - dychloroethane (385000 tonnesyr) is obtained by reaction between HCl ethylene and air Vinyl chloride monomer (280000 tonnesyr) forms from dychloroethane cracking VCM is polymerised in aqueous solution and then dried to produce polyvinyl chloride powder (200000 tonnesyr) Butadiene production (nominal capacity is 60000 tonnesyr) Butadiene is obtained after butanes splitting and absorption in dymethyl-formalamide studies For the VCM plant the possibility of medium pressure steam (MPS) generation has been identified This fact explains the reason why hot utility saving exceeds the 100 value For several processes there is not the chance to save on cold utilities

116 163 165261

39

205 235

008

175273

00

13

1592

000000 000 0629

979

0

Crackin

g

Butadien

e DP3

MDDW+HF1 ISO

RC3

VBampTC

GPL splitt

ingMero

x

Naphtha sp

litting

SW1VCM

PVC TDI

Hot utility saving

Cold utility saving

Figure 313 Energy savings identified by pinch methodology [51 Pini 2005]

Applicability Pinch methodology is widely used for the design of new units and for the retrofitting of existing ones It has many applications such as bull energy analysis of process units bull utility plus heat and power system analysis bull heat exchanger network design and analysis bull total site analysis to optimise process and utility integration bull hydrogen and water system analysis

Chapter 3

84 Version April 2006 SSEIPPCBENE_Draft_1

Pinch is a heavy and expensive tool for companies The implementation of this methodology needs a great number of data and a deep knowledge of the process For some processes eg where a single type of streams (cold or hot) exists pinch methodology is not applicable Experienced professionals are needed to implement Pinch methodology The team consists of Pinch expert process simulation experts experts to handle cost estimations and plant operation experts to comment on the results PC computer and Pinch software are needed

Cross-media effects bull increasing process throughout by eliminating energy bottlenecks

Economics bull implementing study costs are dependent on the size of the analysis starting from

EUR 100000 per case Implemented energy saving cases covers non-investment operational changes and process modification investments which typically have a short payback time In grass root cases Pinch can reduce investment costs

Driving force for implementation Economic savings and environmental benefits are the reasons for using Pinch methodology

Example plants

bull Neste Oil in Finland Porvoo and Naantali refineries (wwwnesteoilcom) bull Borealis Polymers Oy Finland (wwwborealisgroupcom)

Reference information [117 Linnhoff March ] [118 KBC ] [119 Neste Jacobs Oy ] [12 Pini 2005] [51 Pini 2005] [67 Marttila 2005]

325 Benchmarking Description of the energy efficiency technique Benchmarking is simply said to be lsquoimproving ourselves by learning from othersrsquo but can also be defined- eg in following ways bull lsquobenchmarking is about making comparisons with other companys and then learning the

lessons which those companies each show uprsquo (The European Benchmarking Code of Conduct)

bull lsquobenchmarking is the practice of being humble enough to admit that someone else is better at something and being wise enough to learn how to be as good as them and even betterrsquo (American Productivity and Quality Center)

Executive Summary

SSEIPPCBENE_Draft_1 Version April 2006 i

EXECUTIVE SUMMARY

To be written upon completion of the whole document

Preface

SSEIPPCBENE_Draft_1 Version April 2006 iii

PREFACE

1 Status of this document Unless otherwise stated references to lsquothe Directiversquo in this document means the Council Directive 9661EC as amended by Directive 200387EC on integrated pollution prevention and control As the Directive applies without prejudice to Community provisions on health and safety at the workplace or any energy efficiency provisions so does this document This document is a working draft of the European IPPC Bureau It is not an official publication of the European Communities and does not necessarily reflect the position of the European Commission

2 The mandate of the work The mandate for this document is threefold a) to implement a special request from the Commission Communication on the

implementation of the European Climate Change Programme (COM(2001)580 final) ECCP concerning energy efficiency in industrial installations The ECCP asks that effective implementation of the energy efficiency provisions of the IPPC Directive are promoted and that a special horizontal BREF addressing generic energy efficiency techniques is prepared

b) gives general guidance to operators and regulators on how to approach and implement

energy efficiency requirements set out in the IPPC Directive and c) be one of several measures foreseen in the European Climate Change Programme aimed at

reducing the emissions of greenhouse gases This document on energy efficiency has links to other Commission instruments eg the following actions have an interface with this document bull Green Paper on Energy Efficiency COM(2005)265 final of 22 June 2005 bull Directive on greenhouse gas emission trading (200387EC) bull Directive on the promotion of cogeneration (20048EC) bull Directive on the energy performance of buildings (200291EC) bull proposal on energy end-use energy efficiency and energy services COM(2003)739 bull the framework Directive for the setting of eco-design requirements for energy using

products EuP (200532EC) bull an Energy Efficiency Toolkit for SMEs developed in the framework of the EMAS

Regulation bull several studies and projects under the umbrella Intelligent Energy ndash Europe and SAVE

which deal with energy efficiency in buildings and industry

3 Relevant legal obligations of the IPPC Directive and the definition of BAT In order to help the reader understand the legal context in which this document has been drafted some of the most relevant provisions of the IPPC Directive including the definition of the term lsquobest available techniquesrsquo are described in this preface This description is inevitably incomplete and is given for information only It has no legal value and does not in any way alter or prejudice the actual provisions of the Directive

Preface

iv Version April 2006 SSEIPPCBENE_Draft_1

The purpose of the Directive is to achieve integrated prevention and control of pollution arising from the activities listed in its Annex I leading to a high level of protection of the environment as a whole including energy efficiency The legal basis of the Directive relates to environmental protection Its implementation should also take account of other Community objectives such as the competitiveness of the Communityrsquos industry thereby contributing to sustainable development More specifically it provides for a permitting system for certain categories of industrial installations requiring both operators and regulators to take an integrated overall look at the polluting and consuming potential of the installation The overall aim of such an integrated approach must be to improve the management and control of industrial processes so as to ensure a high level of protection for the environment as a whole Central to this approach is the general principle given in Article 3 that operators should take all appropriate preventative measures against pollution in particular through the application of best available techniques enabling them to improve their environmental performance including energy efficiency Competent authorities responsible for issuing permits are required to take account of the general principles set out in Article 3 when determining the conditions of the permit These conditions must include emission limit values supplemented or replaced where appropriate by equivalent parameters or technical measures According to Article 9(4) of the Directive these emission limit values equivalent parameters and technical measures must without prejudice to compliance with environmental quality standards be based on the best available techniques without prescribing the use of any technique or specific technology but taking into account the technical characteristics of the installation concerned its geographical location and the local environmental conditions In all circumstances the conditions of the permit must include provisions on the minimisation of long-distance or transboundary pollution and must ensure a high level of protection for the environment as a whole Member States have the obligation according to Article 11 of the Directive to ensure that competent authorities follow or are informed of developments in best available techniques

4 The IPPC Directive and energy efficiency Energy efficiency is not restricted to any one industry sector mentioned in Annex 1 to the Directive as such but is a horizontal issue which is required to be taken into account in all cases In the Directive there are indirect and direct references in energy efficiency in the following articles which will then be explained bull 211 definition of BAT indirect reference bull Annex IV considerations included in BAT direct reference This Directive requires that permits must contain conditions based on Best Available Techniques (BAT) as defined in Article 211 of the Directive to achieve a high level of protection of the environment as a whole A high level of protection means that in issuing the installations permits the regulators have to consider all environmental effects caused by the installation including the effects of energy use Article 211 of the Directive specifies BAT in the following way lsquoBestrsquo shall mean most effective in achieving a high general level of protection of the environment as a whole lsquoAvailablersquo techniques shall mean those developed on a scale which allows implementation in the relevant industrial sector under economically and technically viable conditions taking into consideration the costs and advantages whether or not the techniques are used or produced inside the Member State in question as long as they are reasonably accessible to the operator

Preface

SSEIPPCBENE_Draft_1 Version April 2006 v

lsquoTechniquesrsquo shall include both the technology used and the way in which the installation is designed built maintained operated and decommissioned Furthermore Annex IV specifies what considerations must be taken into account generally or in specific cases when determining best available techniques as defined in Article 2 (11) bearing in mind the likely costs and benefits of a measure and the principles of precaution and prevention The references to energy efficiency in the IPPC Directive are a) Annex IV One of the issues to be taken into account is the consumption and nature of raw

materials (including water) used in the process and their energy efficiency (item 9)b) Article 3 (d) direct reference The Directive requires that Member States shall take the

necessary measures to provide that the competent authorities ensure that installations are operated in such a way that among other things energy is used efficiently (Article 3 (d))

c) Article 61 direct reference In Article 6 it is said that Member States shall take the necessary measures to ensure that an application to the competent authority for a permit includes a description of the raw and auxiliary materials other substances and the energy used in or generated by the installation

d) Article 91 indirect reference In Article 91 concerning conditions of the permit it is stipulated that Member States shall ensure that the permit includes all measures necessary for compliance with the requirements of Articles 3 and 10

e) Article 93 direct reference (amendment) In Article 93 (amendments by Directive 200387EC) concerning limit values it is stipulated that IPPC-permit shall not include an emission value for direct emissions of that gas meaning greenhouse gases specified in Annex 1 to Directive 872003

Furthermore it is stipulated that for activities listed in Annex 1 to Directive 200387EC Member States may choose not to impose requirements relating to energy efficiency in respect of combustion units or other units emitting carbon dioxide on the site Directive 200387EC covers some but not all activities covered by the IPPC Directive This document gives general advice how to implement those requirements

5 Objective of this document Article 16(2) of the Directive requires the Commission to organise lsquoan exchange of information between Member States and the industries concerned on best available techniques associated monitoring and developments in themrsquo and to publish the results of the exchange

The purpose of the information exchange is given in recital 25 of the Directive which states that lsquothe development and exchange of information at Community level about best available techniques will help to redress the technological imbalances in the Community will promote the worldwide dissemination of limit values and techniques used in the Community and will help the Member States in the efficient implementation of this Directiversquo The Commission (Environment DG) established an information exchange forum (IEF) to assist the work under Article 16(2) and a number of technical working groups have been established under the umbrella of the IEF Both IEF and the technical working groups include representation from Member States and industry as required in Article 16(2)

Preface

vi Version April 2006 SSEIPPCBENE_Draft_1

The aim of this series of documents is to reflect accurately the exchange of information which has taken place as required by Article 16(2) and to provide reference information for the permitting authority to take into account when determining permit conditions By providing relevant information concerning best available techniques these documents should act as valuable tools to drive environmental performance including energy efficiency The special target of this document is to provide a comprehensive energy management structure which makes it possible for companies to demonstrate their energy efficiency and competent authorities to verify it This general structure will later be tailored for different sectors in sectoral BREFs The background and mandate of this work concerning generic energy efficiency techniques for industry differs from other BREFs in the sense that this document is prepared in the IPPC context but it can be used in a broader scope

6 Information Sources This document represents a summary of information collected from a number of sources including in particular the expertise of the groups established to assist the Commission in its work and verified by the Commission services All contributions are gratefully acknowledged

7 How to understand and use this document The information provided in this document is intended to be used as an input to the recommendations for goodbest practices to contribute energy efficiency in IPPC installations When determining BAT and setting BAT-based permit conditions account should always be taken of the overall goal to achieve a high level of protection for the environment as a whole including energy efficiency The rest of this section describes the type of information that is provided in each section of this document Chapter 1 provides general information on the basics of energy and thermodynamics It explains main features of energy and principles of thermodynamics as an introduction for understanding energy applications in industry and their restrictions Chapter 2 provides information on the definitions of energy efficiency relevant for industry and how to develop indicators to monitor energy efficiency Furthermore it deals with different aspects which influence energy efficiency some of them which company has control and some of them not It also gives examples how different system boundaries influence the energy efficiency Chapter 3 provides information on good energy management in industrial installations in broad terms It explains why good structured management is important and which issues will be considered and taken into account in a good system It covers the elements which are crucial to manage energy issues efficiently both from an environmental and economical point of view It gives examples of good management structures approaches audits methodologies and other tools which could be implemented to improve energy efficiency Systematic and transparent way to deal with energy issues is essential to reach best economical and environmental results Chapter 4 provides information on generic energy producing and using systems and unit operations which can be found in several industries It describes energy saving techniques related to these systems (eg steam system) and unit operations (eg motors) The approach is to describe different strategies to improve energy efficiency in these systems and also describe commonly used energy saving techniques (eg heat recovery) separately

Preface

SSEIPPCBENE_Draft_1 Version April 2006 vii

Chapter 5 recommends the best practices to be used in companies to manage energy issues Since the best available techniques change over time this document will be reviewed and updated as appropriate All comments and suggestions should be made to the European IPPC Bureau at the Institute for Prospective Technological Studies at the following address

Edificio Expo cInca Garcilaso sn E-41092 Sevilla Spain Telephone +34 95 4488 284 Fax +34 95 4488 426 e-mail JRC-IPTS-EIPPCBceceuint Internet httpeippcbjrces

SSEIPPCBENE_Draft_1 Version April 2006 ix

Best Available Techniques Reference Document on ENERGY EFFICIENCY TECHNIQUES

EXECUTIVE SUMMARYI PREFACE III SCOPE XVII 1 GENERAL FEATURES ON ENERGY 1

11 Introduction 1 111 Forms of energy 1 112 Energy transfer and storage 2 113 Energy losses 3 114 Exergy 3

12 Principles of thermodynamics 4 121 Characterisation of systems and processes 4 122 Forms of energy storage and transfer 4 123 Properties enthalpy and specific heat 5 124 Properties entropy and exergy 6

13 First and second laws of thermodynamics 7 131 First law of thermodynamics ndash energy balance 7

1311 Energy balance for closed systems 7 1312 Energy balance for open systems7 1313 Calculation of internal energy and enthalpy changes8 1314 First law efficiencies thermal efficiency and coefficient of performance 8

132 Second law of thermodynamics - entropy balance 9 133 Combination of the first and second laws - exergy balance 10

1331 Exergy balance for a closed system 10 1332 Exergy balance for an open system10 1333 Calculation of flow exergy changes11 1334 Second law efficiency exergetic efficiency11

14 Property diagrams tables databanks and computer programs 12 141 Pressure-temperature diagram 12 142 Pressure-specific volume and temperature-specific volume diagrams 13 143 Temperature-entropy diagram 14 144 Enthalpy-entropy diagram 15 145 Property tables databanks and simulation programs 15

15 Identification of inefficiencies 16 151 Case 1 Throttling devices 17 152 Case 2 Heat exchangers 19 153 Case 3 Mixing processes 21

2 ENERGY EFFICIENCY 27 21 Definitions of energy efficiency 27 22 Energy efficiency indicators in industry 28

221 Production processes 29 222 Energy intensity factor and energy efficiency index 29 223 Energy efficiency in production units 30 224 Energy efficiency of a site 34

23 Issues to be considered when defining energy efficiency indicators 35 231 System boundaries 35

2311 Definition of the system boundary35 2312 Examples of system boundaries36 2313 Some remarks on system boundaries 40

232 Other items to be decided by the company 41 233 Structural issues 45

24 Examples of application of energy efficiency 48 241 Mineral oil refineries 48 242 Ethylene cracker 49 243 VAM production 50 244 A rolling mill in a steel works 51 245 Heating of premises 53

3 ENERGY MANAGEMENT IN INDUSTRIAL INSTALLATIONS 55 31 The structure and the content of energy management 55

x Version April 2006 SSEIPPCBENE_Draft_1

311 General features and factors 55 312 Commitment of the top management 58 313 Planning 59

3131 Initial energy audit 59 3132 Energy performance targets 60 3133 Action plan 61

314 Doing 61 3141 Structures and responsibilities 62 3142 Awareness raising and capacity building62 3143 Communication and motivation63

315 Checking 63 3151 Monitoring and measurement 63 3152 Records 64 3153 Periodic energy audits64

316 Acting 64 317 Examples of energy management systems and its implementation 65

32 Methodologies and tools for energy use optimisation and energy efficiency 65 321 Energy audits 65

3211 Audit models66 32111 The scanning models67 32112 The analysing models68 32113 The technical coverage of energy audit models 69

3212 Audit tools 71 322 Energy monitoring 72 323 Energy models 73

3231 Example 1 Electric energy models74 3232 Example 2 Thermal energy models77 3233 Energy diagnosis using the energy models 79

324 Pinch methodology 81 325 Benchmarking 84 326 Assessment methods 88

3261 Time series comparison 88 3262 Comparison with theoretical approaches 89 3263 Benchmarks approaches90

327 Qualification of components in representative conditions 91 328 Cost calculations 93 329 Checklists 93 3210 Good housekeeping 93 3211 E-learning 93

33 Energy services company (ESCO) concept 93 34 Public schemes and tools to motivate energy saving in industry 94

341 Tax deductions for energy saving investments 94 342 Ecology premium 95 343 Support for demonstration projects in energy technology 96 344 Cogeneration certificates (blue certificates) 96 345 Energy planning regulation 97 346 Benchmarking covenant 98 347 Audit covenant 99 348 Energy saving certificates (white certificates) 100 349 EMAT - energy managerrsquos tool 102 3410 Energy saving agreements 103

4 APPLIED ENERGY SAVING TECHNIQUES 105 41 Introduction 105 42 Combustion 106

421 Choice of combustion techniques 106 422 Strategies to decrease losses in general 107 423 High temperature air combustion technology (HiTAC) 111

43 Steam systems 114 431 General features of steam 115 432 Measures to improve steam system performance 117 433 Use of economisers to preheat feed-water 119 434 Prevention removal of scale deposits on heat transfer surfaces 120 435 Minimising blowdown 122 436 Recovering heat from the boiler blowdown 124

SSEIPPCBENE_Draft_1 Version April 2006 xi

437 Implementing a control and repairing programme for steam traps 126 438 Collecting and returning condensate to the boiler for re-use 128 439 Re-use of flash steam 130 4310 Insulation on steam pipes and condensate return pipes 131 4311 Installation of removable insulating pads on valves and fittings 132 4312 Use of flash steam on the premises through recovery of condensate at low pressure 133 4313 Installing an air preheater 134 4314 Minimising boiler short cycling losses 136

44 Power production 137 45 Cogeneration 138

451 Different types of cogeneration 138 452 CHP in soda ash plants 144 453 Stationary reciprocating engine solutions 145 454 Trigeneration 148 455 District cooling 151

46 Waste heat recovery 154 461 Direct heat recovery 155 462 Heat pumps 157 463 Surplus heat recovery at a board mill 161 464 Mechanical vapour recompression (MVR) 163 465 Acid cleaning of heat exchangers 166 466 Heat exchangers with flashed steam - design 168

47 Electric motor driven systems 171 48 Compressed air systems 177

481 General description 177 482 Improvement of full loadno load regulation system 181 483 Variable speed drive technology (VSD) 182 484 Optimising the pressure level 184 485 Reducing leakages 186

49 Pumping systems 187 491 General description 187 492 Choice between steam turbine driven pumps and electrical pumps 188 493 Vacuum pumps replacing steam ejectors 192

410 Drying systems 193 4101 General description 193 4102 Techniques to reduce energy consumption 195

41021 Mechanical processes 195 41022 Computer-aided process controlprocess automation195 41023 Selecting the optimum drying technology 196

411 Process control systems 196 4111 General features 196 4112 Energy management and optimisation software tools 200 4113 Energy management for paper mills 201 4114 Fluidised bed boiler combustion optimisation 204 4115 Steam production and utilisation optimisation using a model predictive controller 205

412 Transport systems 207 413 Energy storage 211

5 BEST PRACTICES 213 51 Generic best practices 214 52 Energy efficiency indicators 214 53 Energy management structure and tools 215 54 Techniques to improve energy efficiency 216

541 Combustion 216 542 Steam systems 217 543 Cogeneration 217 544 Heat recovery 218 545 Electric motor drive systems 218 546 Compressed air systems 219 547 Pumping systems 219 548 Drying systems 219 549 Transport systems 219

6 CONCLUDING REMARKS 221

xii Version April 2006 SSEIPPCBENE_Draft_1

7 REFERENCES 223 8 GLOSSARY 227 9 ANNEXES 233

91 Annex 1 233

SSEIPPCBENE_Draft_1 Version April 2006 xiii

List of figures Figure 11 Pressure-temperature diagram 12 Figure 12 P-v diagram 13 Figure 13 T-v diagram 14 Figure 14 Temperature-entropy diagram 14 Figure 15 Enthalpy-entropy diagram 15 Figure 16 Steam throttling process 18 Figure 17 T-s and h-s diagrams for the steam throttling process of the example 18 Figure 18 Counterflow heat exchanger 20 Figure 19 Reheating process of a steam flow 20 Figure 110 T-s and h-s diagram for the steam reheating process of the example 21 Figure 111 IiRT0 versus molar fraction of one component in the mixture 22 Figure 112 Mixing chamber of two flows 23 Figure 113 T-s diagram for the mixing process of the example 24 Figure 21 Energy vectors in a simple production unit 30 Figure 22 Energy vectors in a production unit 32 Figure 23 Inputs and outputs in a site 34 Figure 24 System boundary ndash old electric motor 36 Figure 25 System boundary ndash new electric motor 37 Figure 26 System boundary ndash electric motor + old pump 37 Figure 27 System boundary ndash electric motor + new pump 38 Figure 28 Electric motor + new pump with constant output 38 Figure 29 New electric motor new pump and old heat exchanger 39 Figure 210 New electric motor new pump and two heat exchangers 40 Figure 211 Inputs and outputs for a vinyl acetate monomer (VAM) plant 50 Figure 212 Flow chart of a rolling mill 51 Figure 213 Specific energy consumption in a rolling mill 52 Figure 214 Specific energy consumption in a rolling mill 53 Figure 215 Energy consumption depending on outdoor temperature 53 Figure 216 Energy consumption depending on outdoor temperature 54 Figure 31 The plan-do-check-act-cycle (PDCA) 57 Figure 32 Continuous improvement of an energy management system 57 Figure 33 Basic energy auditing models 66 Figure 34 The properties of energy audit models 66 Figure 35 Coverage of an industrial site energy audit 69 Figure 36 Coverage of a district heating connected to a residential building energy audit 70 Figure 37 Coverage of a CHP plant energy audit 70 Figure 38 Structure of a monitoring system 72 Figure 39 Monitoring process 73 Figure 310 Power factor of a device depending on the load factor 75 Figure 311 Scheme of energy diagnosis 80 Figure 312 Hot and cold streams in Pinch methodology 81 Figure 313 Energy savings identified by pinch methodology 83 Figure 314 Mechanism when an ESCO is involved 100 Figure 41 Energy balance of a combustion installation 107 Figure 42 Working principle for regenerative burners 111 Figure 43 Different regions of combustion 112 Figure 44 The net heat output of test furnaces resulted by both conventional and HiTAC burners 113 Figure 45 Distribution of the energy content of steam in the sensible and latent component depending on

absolute pressure 116 Figure 46 Back-pressure plant 139 Figure 47 Extraction condensing plant 139 Figure 48 Gas turbine heat recovery boiler 140 Figure 49 Combined cycle power plant 140 Figure 410 Reciprocating plant 141 Figure 411 Comparison between efficiency of condensing power and combined heat and power plant142 Figure 412 Trigeneration compared to separate energy production 148 Figure 413 Trigeneration enables optimised plant operation around the year 149 Figure 414 District cooling in the winter by free cooling technology 152 Figure 415 District cooling by absoption technology in the summer 152 Figure 416 Diagram of a compression heat pump 158 Figure 417 Diagram of an absorption heat pump 159

xiv Version April 2006 SSEIPPCBENE_Draft_1

Figure 418 Heat recovery system connected to the district heating system 162 Figure 419 Simple MVR installation 163 Figure 420 COP versus temperature lift for a typical MVR system 164 Figure 421 Process scheme of Eurallumina alumina refinery 166 Figure 422 Operative cycle of heaters 167 Figure 423 A section of the heater 169 Figure 424 Scales in the tube bundle 170 Figure 425 A compressor motor with a rated output of 24 MW 173 Figure 426 Some methods of capacity control of a centrifugal pump 175 Figure 427 Performance of compressors with different controls 175 Figure 428 Pump power consumption 176 Figure 429 Fans with different controls 176 Figure 430 Compressed air system 178 Figure 431 Energy flow diagram for an inefficient compressed air station 179 Figure 432 Compressor lifecycle costs 183 Figure 433 Different kinds of compressor control 184 Figure 434 Steam distribution scheme of the alumina refinery 189 Figure 435 Bandwidths for the specific secondary energy consumption of different types of dryer when

vaporising water 194 Figure 436 Structure of an energy management tool 200 Figure 437 Paper mill energy management (system layout) 202 Figure 438 Tracking deviations from optimum consumption 202 Figure 439 Steam flow depending on fuel and time 204 Figure 440 Variable definition matrix 206

Scope

SSEIPPCBENE_Draft_1 Version April 2006 xv

List of tables Table 11 Some values of the derivatives 22 Table 12 Maximum values for mistures 23 Table 31 Energy management matrix 56 Table 32 A simple electric model 75 Table 33 Data ina thermal energy model (generators side) 77 Table 34 Data in a thermal energy model (users side) 78 Table 35 Steps in Pinch methodology 82 Table 36 Information template for energy efficiency motivation tools 94 Table 37 Areas covered in the application 102 Table 41 The template for information on energy efficiency techniques 105 Table 42 Higher and lower calorific values of certain fuels 107 Table 43 Differences in heat transfer 121 Table 44 Energy content of blowdown 123 Table 45 Recovered energy from blowdown losses 125 Table 46 Various operating phases of steam traps 126 Table 47 Operating factors for steam losses in steam traps 127 Table 48 Load factor for steam losses 127 Table 49 Percentage of total energy present in the condensate at atmospheric pressure and flash steam

129 Table 410 Percentage of total energy present in the condensate at atmospheric pressure and flash steam

130 Table 411 Heat losses per metre of pipes in function of the operating temperature and insulation

thickness 132 Table 412 Calculation of the Siegert Co-efficient for different types of fuel 135 Table 413 Technical data for the Barajas Airport trigeneration plant 151 Table 414 Components of an electric motor drive system 171 Table 415 Possible energy saving measures in compressed air systems 180 Table 416 Leakage costs 186 Table 91 Saturated water properties 234 Table 92 Superheated water properties I 235 Table 93 Superheated water properties II 236

Scope

SSEIPPCBENE_Draft_1 Version April 2006 xvii

SCOPE This document together with other BREFs in the series (see list on the reverse of the title page) are intended to cover the energy efficiency issues under IPPC Directive This document also responds to the special request from the Commission Communication on the implementation of the European Climate Change Programme (COM(2001)580 final) ECCP concerning energy efficiency in industrial installations The ECCP asks that effective implementation of the energy efficiency provisions of the IPPC Directive are promoted and that a special horizontal BREF addressing generic energy efficiency techniques is prepared The target of this document is to provide information on how to improve energy efficiency in industrial installations by giving generic guidance on how to approach assess implement and deal with energy efficiency related issues along with corresponding permit and supervising procedures Many of the proposed measures tools and methodologies dealt with may also be implemented in non-IPPC installations This document deals with generic energy efficiency techniques and best practices which can be applied in several industrial sectors without duplicating the work done in sectoral BREFs However it can feed other work that is in progress with information and ideas The coverage of this document is as follows bull industrial sectors which use or produce energy and apply generic techniques which are

possible to transfer to other sectors are covered bull it does not develop or conclude on sector specific techniques but will use examples from

various industry sectors to derive generic conclusions bull equipment (eg pumps fans) as parts of systems and installations are dealt with without

drawing conclusions which could conflict with EuP implementing measures bull it does not respond to fuel specific (eg bio fossil waste) issues bull the system boundary is set in most cases round the site but in some cases also smaller or

larger boundaries are considered The main question to be answered in this document is the following How to demonstrate if energy is used and produced efficiently

For finding answers to this question this document deals with the following issues bull what are appropriate definitions for energy efficiency bull what are and how to use energy efficiency indicators bull what methodologies techniques etc contribute to good energy management bull what are the possible measures both techniques and practices to improve energy

efficiency bull what are possible motivation tools To answer all the above-mentioned questions this document deals with the following issues bull energy management including different types of auditing bull methodologies bull monitoring bull indicators and measurements bull applied techniques and good practices

xviii Version April 2006 SSEIPPCBENE_Draft_1

In order to further clarify the scope the following can be said bull because energy efficiency means different things for different stakeholders clarification on

what energy efficiency means in this document is required First a distinction needs to be made between energy efficiency at the macro level (eg national) and at the micro level (eg company level) In this document only the latter is discussed

bull energy efficiency is dealt with from an industrial perspective within the installation boundaries without considering a productrsquos life cycle This is in line with the IPPC Directive which deals with production and not with products The fuel by which energy is produced is also not considered in this document

bull this document deals with production activities in industrial installations but energy demand of products is outside the scope Furthermore fuel specific issues are neither dealt with in this document

bull those techniques and measures to improve energy efficiency which are sector specific are not dealt within here but in sectoral BREFs For example it exists a BREF on large combustions plants where energy efficiency is also covered

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 1

1 GENERAL FEATURES ON ENERGY [2 Valero-Capilla 2005] [3 FEAD and Industry 2005] [97 Kreith 1997] This chapter deals with the basics of energy and thermodynamics It explains the main features of energy and the principles of thermodynamics as an introduction for understanding energy applications and their restrictions in industry There is a lot of generic information on thermodinamics available in the general literature

11 Introduction Energy is needed to fulfil the necessary or imagined needs of people To do this energy is needed directly (eg heating lighting) or indirectly (eg energy in products) Industry needs energy as one production factor to manufacture goods and provide services to the society Decoupling energy demand and supply is a challenging task

111 Forms of energy Energy can take a wide variety of forms There are five main forms of energy generally required in industry bull chemical energy the energy that bonds atoms or ions together (eg fuels) bull mechanical energy associated with motion bull thermal energy (or heat) the internal motion of particles of matter bull electrical (or electromagnetic) energy associated with the electrical charges and the

movement of them bull nuclear energy energy in the nuclei of atoms which can be released by fission or fusion of

the nuclei Chemical energy is stored in fuels and can be converted directly to mechanical energy (combustion engines) or to thermal energy (direct process heating) However most often the chemical energy is converted to a more usable form generally either to electrical energy or mechanical energy to drive machines or thermal energy as the source of a process

Mechanical energy can exist into two states kinetic or potential Kinetic energy is the energy that moving objects have due to their motion For example it can be an alternative motion (eg a piston) a rotary motion (eg transmission shaft) or a waterfall Potential energy is the energy stored in an object due to its position for instance water stored by a dam Thermal energyheat is quantified by temperature It can be created by chemical reactions such as burning nuclear reactions electromagnetic dissipation (as in electric stoves) or mechanical dissipation (such as friction)

Electrical energy or electromagnetic energy is a form of energy present in any electric field or magnetic field or in any volume containing electromagnetic radiation Nuclear energy will not be dealt within this document Energy can also be expressed as primary and secondary energies usually for statistical purposes Primary energy is energy contained in raw fuels and any other forms of energy received by a system as input to the system Primary energies are transformed to secondary energies in energy conversion processes to more convenient forms of energy such as electrical energy

Chapter 1

2 Version April 2006 SSEIPPCBENE_Draft_1

112 Energy transfer and storage Transfer Energy cannot be created or destroyed Energy can only be converted from one form to another (first law of thermodynamics see Section 131) Energy is converted to make it more useful for different purposes in industry and all society Energy found in fossil fuels solar radiation or nuclear fuels needs to be converted into other energy forms such as electrical propulsive or cooling to be useful Energy conversion is any process of converting energy from one form to another The efficiency of a converting machine characterises how well it can convert the energy Energy conversion can be done by eg the following means bull electricity can be turned into mechanical energy by an electrical motor bull inversely mechanical energy can be converted into electricity by an alternator bull thermal energy can be transformed into mechanical energy by a turbine bull electricity can be converted into heat by a resistance bull chemical energy can be turned into heat during a chemical reaction and also into (kinetic)

mechanical energy and heat for instance in an explosion bull an internal combustion engine converts chemical energy in the gasoline to the propulsive

energy that moves a car bull a solar cell converts solar radiation into electrical energy that can then be used to light a

bulb or power a computer Storage The storage of different forms of energy (see Section 111) are quite different Some are difficult or even impossible to store as such Electricity can hardly be stored as such Batteries store potential electrical energy but in fact chemically Mechanical and thermal energies can be stored in the medium term as potential energy water damshot water tanks but in general they are not so easy to store One of the most convenient ways for storing energy is undoubtedly as chemical energy in a material It can be stored for a long and even sometimes very long time It can be transported and it is often easy and quick to implement The most important chemical sources of energy are the fuels

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 3

113 Energy losses Energy losses are very different according to the transformation it undergoes Furthermore the transformation is neither total nor unique eg an electrical motor also generates heat Losses are unavoidable to some extent (second law of thermodynamics see Section 132) The following examples illustrate the losses from a combustion plant and from electricityheat conversion Combustion plant bull the first energy losses are due to incomplete combustion of the fuel Part of the fuel is not

burnt at all or only partially and in this case produces other reactants (such as CO2) than the ones resulting from complete combustion This is an incomplete conversion of chemical energy into thermal energy

bull some other losses are due to an incomplete transfer of the heat of the combustion gases to the watersteam of the boiler losses through the lagging of the combustion chamber and of the boiler losses to the air by the flue-gas losses to the air via the ashes

bull the heat of the combustion gases is mostly transferred to the steam cycle but part of it is transferred to the air instead of the fluid which is required (watersteam)

bull similarly if heat is exported via a heat exchanger there will be some losses by transfer of part of it to the air instead of to the secondary fluid

bull when steam is sent to a turbo generator set part of its energy is transferred to the air by direct heat losses and mechanical frictions in the turbo generator set However most of the losses here are due to the latent heat which is released by steam when condensed at the cold source The latent heat is the energy released or absorbed during a change of state (released when passing from the gaseous state of steam to the liquid state of water) Of course the losses are significantly reduced if this energy can be used as happens in the case of cogeneration

Electricityheat conversion bull when turning electricity into heat nearly 100 of the electricity input will be turned into

heat However converting the heat released by the combustion of a fuel into electricity can typically result a conversion efficiency of about 35 of the fuel energy input Using electricity just for making heat is not considered to be an efficient use of energy since the electricity which is used was most probably made from heat in a thermal cycle So it is much more beneficial when possible to use a heat source directly than to convert heat into electricity then electricity into heat even if the second transformation is made with high efficiency

114 Exergy The term lsquoexergyrsquo is used to describe differences in energy quality in other words exergy shows the maximum useful work obtainable in the system The exergy content of a system indicates its distance from the thermodynamic equilibrium See Section 124 and 133 For instance 1 GJ of steam at 400 degC40 bar contains the same energy as 1 GJ of water at 40 degC but different exergy The usefulness of these energies are really different on the one hand there is 300 kg of steam on the other 6 tonnes of water and steam at 40 bar can be used for generating electricity moving mechanical equipment heating etc but there is little use for water at 40 degC The exergy of low temperature energies can be raised by eg heat pumps

Chapter 1

4 Version April 2006 SSEIPPCBENE_Draft_1

12 Principles of thermodynamics Thermodynamics is the physics that deals with the relationships and conversions between heat and other forms of energy 121 Characterisation of systems and processes A system (as a thermodynamic concept) is the quantity of matter within the prescribed boundary under consideration everything external to the system is called the surroundings Systems may be considered as closed or open A system can be considered closed if there is no interchange of matter between the system and the surroundings If there is an interchange the system is considered to be open A very important class of systems that is frequently encountered by engineers is steady-flow systems A steady-flow system can be defined as any fixed region-of-space system through which a fluid flows and the properties of this fluid either internal to the system or at its boundaries do not change as time passes Typical examples include air compressors gas turbines steam turbines boilers pumps heat exchangers etc All these devices have in common that each has one or more fluid streams entering and leaving Devices with these characteristics are also known as steady-state steady-flow systems steady-flow control volumes and flow systems Any characteristic of a system is called property Temperature volume pressure or mass are some of the most familiar examples

122 Forms of energy storage and transfer The energy of a system consists of the kinetic potential and internal energies expressed as

mgzmCUPTKNUU PK ++=++=2

2

(J) Equation 11

Where

bull U is the internal energy which is associated with the microscopic forms of energy ie to the motion position and internal state of the atoms or molecules of the substance

bull KN is the kinetic energy which is associated to the motion of the system as a whole relative to some reference frame

bull C is the velocity of the system relative to some fixed reference frame bull m is the mass of the body in motion

bull PT is the change in gravitational potential energy which is associated with the position of the system as a whole (elevation) in the earthrsquos gravitational field

bull g is the gravitational acceleration

bull z is the elevation of the centre of gravity of a system relative to some arbitrarily selected reference frame

Thermal energy is a huge drain of energy when compared with kinetic or potential energies Therefore in many energy analyses these two last energies may be disregarded Energy storage Energy can be stored in numerous forms (some more information in Section 112) The most important encountered forms in thermodynamic applications are internal kinetic and potential energy Other forms of energy such as magnetic electric and surface tension effects are significant only in some specialised cases and will not be considered here

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 5

Energy transfer The forms of energy discussed above which constitute the total energy of a system are static forms of energy and can be stored in a system However energy can also be transformed from one form to another and transferred between systems For closed systems energy can be transferred through work and heat transfer Heat and work are not properties because they depend on the details of a process and not just the end states bull heat (Q) can be defined as energy in transit from one mass to another because of a

temperature difference between the two It accounts for the amount of energy transferred to a closed system during a process by means other than work The transfer of energy occurs only in the direction of decreasing temperature Heat can be transferred in three different ways conduction convection and radiation Conduction is the transfer of energy from the more energetic particles of a substance to the adjacent particles that are less energetic due to interactions between the particles Conduction can take place in solids liquids and gases Convection is the energy transfer between a solid surface at a certain temperature and an adjacent moving gas or liquid at another temperature Finally thermal radiation is emitted by matter as a result of changes in the electronic configurations of the atoms or molecules within it The energy is transported by electromagnetic waves and it requires no intervening medium to propagate and can even take place in vacuum

bull work (W) has the following thermodynamic definition work is done by a system on its surroundings if the sole effect on everything external to the system could have been the raising of a weight Like heat work is also energy in transit

123 Properties enthalpy and specific heat Enthalpy A property related to internal energy U pressure p and volume V is enthalpy H defined by

H = U + pV (J) Equation 12 Or per unit of mass using specific internal energy u and specific volume v (internal energy and volume per unit of mass) as follows h = u + pv (J) Equation 13 Specific heat capacity The property specific heat capacity C (commonly named specific heat) relates energy and temperature The specific heat is defined as the energy required to raise the temperature of a unit mass of a substance by one degree Two different specific heats are usually considered in thermodynamics specific heat at constant volume CV and specific heat at constant pressure CPSpecific heat at constant volume CV expresses the energy required to raise the temperature of the unit mass of a substance by one degree as the volume is maintained as constant The energy required to do the same to the pressure being maintained as constant is the specific heat at constant pressure CP CV and CP are expressed as follows

vv T

uC

partpart

= (JK) Equation 14

pp T

hC

partpart

= (JK) Equation 15

Chapter 1

6 Version April 2006 SSEIPPCBENE_Draft_1

The values of internal energy enthalpy and heat capacities can be calculated as shown in Section 1313 and they are extensively available through property tables databases and programs for a great variety of substances as explained in Section 145

124 Properties entropy and exergy Entropy The concept of entropy is very important to state the second law of thermodynamics in (see Section 132) a general and usable form When two stable states of a system are connected by different internally reversible processes the integral of the heat interchanged over its temperature is found not to be dependent on process path This proves the existence of the function called entropy which only depends on the state of the properties of the system The change of entropy is defined as follows

(JK) Equation 16

Entropy is an abstract property and can be viewed as a measure of disorder Unlike energy entropy is a non-conserved property However entropy is easily calculated following procedures like those explained in Section 143 Thermodynamic databanks as explained in Section 144 include values of entropy for many substances mixtures and pressure and temperature ranges Exergy Exergy of a thermodynamic system is the maximum theoretical useful work (shaft work or electrical work) obtainable as the system is brought into complete thermodynamic equilibrium with the thermodynamic environment while the system interacts with this environment only (some more information can be found in Section 114) A system is said to be in the dead state when it is in thermodynamic equilibrium with its surroundings In the dead state a system is at the temperature and pressure of its surroundings it has no kinetic or potential energy and it does not interact with the surroundings Exergy can be defined as well as a measure of the departure of the state of a system from the environment Once the environment is specified a value can be assigned to exergy in terms of property values for the system only and exergy can be regarded as a property of the system The value of exergy as defined in Equation 17 cannot be negative and is not conserved but destroyed by irreversibilities The specific exergy on a unit mass basis is e = (u-u0) + p0 (v-v0) ndash T0(s-s0) + C22 + gz (J) Equation 17 Where bull 0 denotes the dead state When a mass flows across the boundaries of a control volume there is an exergy transfer accompanying the mass and work flows This is named lsquospecific flow exergyrsquo or lsquophysical exergyrsquo of a material stream and is given by e = (h-h0) - T0 (s-s0) + C22 + gz (J) Equation 18 Flow exergy is commonly used in the analysis of open systems and calculating it is as simple as any other thermodynamic property as explained in Section 14

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 7

13 First and second laws of thermodynamics The two fundamental and general laws of thermodynamics are (1) energy is conserved and (2) it is impossible to bring about any change or series of changes The sole net result of which is the transfer of energy as heat from a low to a high temperature In other words heat will not flow from low to high temperatures by itself A thermodynamic process will not occur unless it satisfies both the first and the second laws of thermodynamics

131 First law of thermodynamics ndash energy balance The first law of thermodynamics is the general principle of physics and it states that energy is conserved Although the law has been stated in a variety of ways all have essentially the same meaning The following are examples of typical statements bull whenever energy is transformed from one form to another energy is always conserved bull energy can neither be created nor destroyed bull the total sum of all energies remains constant for a given system bull the net energy in the form of heat added or removed from a system that operates in a cyclic

manner equals the net energy in the form of work produced or consumed by the system bull the value of the net work done by or on a closed system undergoing an adiabatic process

between two given states depends solely on the end states and not on the details of the adiabatic process

1311 Energy balance for closed systems For a closed system the first law implies that the change in system energy equals the net energy transfer to the system by means of heat and work That is U2 ndash U1 = Q - W (J) Equation 19 In systems undergoing cycles the net work output equals the net heat transfer to the cycle Wcycle = Qin - Qout (J) Equation 110

1312 Energy balance for open systems Most applications of engineering thermodynamics are conducted on a controlled volume basis In such cases the conservation of the mass principle must be applied The time rate of accumulation of mass within the control volume equals the difference between the total rates of mass flow in and out across the boundary as shown below

sumsum minus=2

21

1 mmdtdm

(kgs) Equation 111

The energy rate balance for such a system is

++minus

+++minus= 2

22

22

1

21

11

22gzChmgzChmWQ

dtdU

(W) Equation 112

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For steady-flow systems the mass flowrates and the rates of energy transfer by heat and work are constant with time

sumsum =2

21

1 mm (kgs) Equation 113

Hence at steady state the first law of thermodynamics can be expressed as

++minus

++=minus 2

22

22

1

21

11

22gzChmgzChmWQ (W) Equation 114

1313 Calculation of internal energy and enthalpy changes The change in internal energy and enthalpy for an ideal gas during a process from state 1 to state 2 is determined as follows

int=minus=∆2

112 )( dTTCuuu v (J) Equation 115

int=minus=∆2

112 )( dTTChhh p (J) Equation 116

The values of CV and CP can be obtained through tables databases and programs for many substances as explained in Section 123 For incompressible substances (those whose specific volume or density is constant) CV = CPand following equations can be applied

(J) Equation 117

Where bull Cav is a C value at the average temperature for small temperature intervals ∆h = ∆u + v∆P (J) Equation 118

1314 First law efficiencies thermal efficiency and coefficient of performance

The thermal efficiency η measures the performance of a heat engine and can be defined as the fraction of the heat input that is converted to net work output

in

outnet

QW =η (-) Equation 119

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It can also be expressed as

in

out

QQ

minus= 1η (-) Equation 120

For a power cycle operating between thermal reservoirs at temperatures TH and TC(T temperature H hot and C cold) the thermal efficiency is

H

C

QQ

minus= 1η (-) Equation 121

The maximum efficiency that can be achieved is given by the Carnot efficiency which is shown in Equation 122 below

H

C

TT

minus= 1η (-) Equation 122

The equations above are also applicable to refrigeration and heat pump cycles operating between two thermal reservoirs but for these QC represents the heat added to the cycle from the cold reservoir at temperature TC and QH is the heat discharged to the hot reservoir at temperature TH More informative coefficients are perhaps the Coefficients of Performance COP of any refrigeration cycle COPR and heat pump cycles COPHP given by

CH

CR QQ

QCOP

minus= (-) Equation 123

CH

HHP QQ

QCOPminus

= (-) Equation 124

Unlike the thermal efficiency the value of COP can be greater than unity This means that the amount of heat removed from the refrigerated space can be greater than the amount of work input

132 Second law of thermodynamics - entropy balance The second law of thermodynamics shows which types of transformations are possible or not and in which direction they occur Like the first law the second can be assumed in many different ways and some of them are listed below bull it is not possible to construct a heat engine which produces no other effect than the

exchange of heat from a single source initially in an equilibrium state and the production of work Heat engines must always reject heat to a thermal-energy reservoir

bull no cyclical device can cause heat to transfer from thermal-energy reservoirs at low temperatures to reservoirs at high temperatures with no other effects

bull the total entropy of an engine and all of the surrounding components that interact with the engine must increase when the heat engine is not completely reversible

bull the only processes that can occur are those for which the entropy of the isolated system increases This statement is known as the increase of entropy principle

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133 Combination of the first and second laws - exergy balance The first and second laws can be combined into a form that is useful for conducting analyses of exergy work potential and the second law efficiencies among others This form also provides additional insight into systems their operation and optimisation

1331 Exergy balance for a closed system The exergy balance for a closed system is obtained with the combination of the energy and entropy balances The exergy change in a closed system is equal to the sum of the exergy transfer accompanying heat the exergy transfer accompanying work minus the destruction of exergy The final equation is

[ ]

ndestructioExergy

workngaccompanyi

transferExergy

heatngaccompanyi

transferExergy

jchangeExergy

TVVpWQTT

EEE σδ 0120

2

1

012 )(1 minusminusminusminus

minus=minus=∆ int 44 344 21

443442143421

(J) Equation 125

bull T0 denotes the temperature at ambient conditions bull p0 denotes pressure at ambient conditions bull Tj is the surface temperature where the heat transfer takes place The term T0σ accounts for the destruction of exergy or thermodynamic irreversibility and is often denoted as I The value of exergy destruction is always positive and ideally zero when no irreversibilities are present within the system As explained in this section if the principal task of any energy analyst is to pinpoint irreversibilities it is quite logical to make use of exergy balances instead of the entropy ones This is because exergy has the familiar units of energy rather than units of energy over temperature and exergy can be easily interpreted as the thermodynamic quality part of an energy stream As explained in this section exergy can easily be calculated as any other thermodynamic property once the properties of the surrounding environment are defined Note that exergy is a definition of thermodynamic availability and equivalence and is not a definition of technical usefulness As an example if natural gas is needed for a given process the same amount of exergy with say steam or coal does not satisfy the needs and could not be used alternatively Lack of interpretation is in many cases the real cause of the not so widely used exergy analyses Energy analysts should be quite knowledgeable about thermodynamics

1332 Exergy balance for an open system The exergy rate balance for a control volume is equal to

ndestructioExergyofRate

transferexergyofRate

eee

iiicvj

j j

changeexergyofRate

cv Iememdt

dVcvpWQTT

dtdE

0

01 minusminus+

minusminus

minus= sumsumsum

4444444444 34444444444 21

(W) Equation 126

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For steady-flow systems the balance obtained is

010 IememWQ

TT

ee

eiii

cvjj j

minusminus+minus

minus= sumsumsum (W) Equation 127

1333 Calculation of flow exergy changes The specific exergy change can be evaluated using following equation

)(2

)()( 21

22

21

2102121 zzgCCssThhee minus+minus

+minusminusminus=minus (Jkg) Equation 128

The values of enthalpy and entropy can be obtained either through property tables or with equations in Sections 123 124 and 131

1334 Second law efficiency exergetic efficiency The thermal efficiency and coefficient of performance defined in Section 1314 are based only on the first law of thermodynamics and make no reference to the best possible performance However the exergetic efficiency or second law efficiency overcomes this deficiency and gives a measure of approximation to reversible operation Exergetic efficiencies are useful for distinguishing means for utilising energy resources that are thermodynamically effective from those that are less so They can be used to evaluate the effectiveness of engineering measures taken to improve the performance of a thermal system The exergetic efficiency is defined in a generic form as the ratio between the exergy recovered and the exergy supplied

E recovered ε= E supplied (-) Equation 129

Exergetic efficiency expressions can take many different forms depending on the analysed system For a heat engine the exergy supplied is the decrease in the exergy of the heat transferred to the engine which is the difference between the exergy of the heat supplied and the exergy of the heat rejected The net work output is the recovered exergy For a refrigerator or heat pump the exergy supplied is the work input and the recovered exergy is the exergy of the heat transferred to the high temperature medium for a heat pump and the exergy of the heat transferred from the low temperature medium for a refrigerator More in general exergy producing systems and exergy dissipating ones can be distinguished The objective of the former is to transfer the exergy of the fuels to the products as much as possible thereby minimising both exergy losses and exergy destructions Most of the energy systems fall within this classification such as turbines compressors pumps boilers and most of the engines On the contrary devices exist whose objective is to dissipate a given flow with the less possible exergy input These devices are for instance draft fans for stack gases dryers or lamps among others From the second law point of view the objective of both types of devices is to dissipate as little exergy as possible The second law efficiency of the first devices is never greater than one On the contrary the second law efficiency of the latter devices needs to be as much greater than one as possible In any case both the numerator namely the product or objective and the denominator namely the expended fuel should be expressed in exergy units

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14 Property diagrams tables databanks and computer programs

In the general literature diagrams tables databanks and computer programs exists on thermodynamic properties of substances

141 Pressure-temperature diagram The p-T diagram also called the phase diagram (Figure 11) shows the three phases of a pure substance separated by a line In each of the single-phase regions (solid liquid and gas) the phase of the substance is fixed by the temperature and pressure conditions The lines between one-phase regions are called two-phase regions and represent the conditions where two phases exist in equilibrium In these areas pressure and temperature are not independent and only one intensive property is required to fix the state of the substance The sublimation line separates the solid and vapour regions the vaporisation line separates the liquid and vapour regions and the melting or fusion line separates the solid and liquid regions A substance being to the left of the vaporisation line is said to be at the state of a sub-cooled or compressed liquid if it is found at the right of the same line the substance is in a superheated vapour state All three lines meet at the triple point where all the phases coexist simultaneously in equilibrium In this case there are no independent intensive properties there is only one pressure and one temperature for a substance in its triple state The so called critical point can be found at the end of the vaporisation line At pressures and temperatures above the critical point the substance is said to be at a supercritical state where no clear distinction can be made between liquid and vapour phases

Substances thatexpand on

freezingSubstances that contract

on freezing

Critical pointS L

LV

Triple point

SV

SOLID

SOLID

P

T

Figure 11 Pressure-temperature diagram

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142 Pressure-specific volume and temperature-specific volume diagrams

Figure 12 and Figure 13 show a pressure-specific volume (P-v) and a temperature-specific volume (T-v) diagram respectively The two-phased region labelled liquid-vapour in both diagrams is commonly called the wet or the dome region The state at the top of that region is again the critical point Inside the dome a substance is a mixture of saturated liquid and saturated vapour The area under a given curve on the P-v diagram representing a quasi equilibrium process is

expressed as dvp

v

vint2

1 which is according to Equation 119 the specific boundary work Therefore P-v diagrams are very useful in the analysis of processes involving boundary work The isotherm lines (states with equal temperature) appearing on the P-v diagram indicate that inside the dome the pressure remains constant at a fixed temperature However in the single-phase liquid and vapour regions the pressure decreases as the specific volume increases Similarly the isobars (states with equal pressure) shown on the T-v diagram indicate that inside the dome the temperature remains constant at a fixed pressure but in the single-phase regions the temperature increases with the specific volume

P

f g

Vapour

TgtTC

Liquid-vapour

Liquid

TltTC

Criticalpoint

TC

VTC = critical temperaturef = saturated liquidg = saturated gas

Figure 12 P-v diagram

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V

T

f g

VapourLiquid

Liquid-vapour

PltPC

PgtPC

PC

Criticalpoint

PC = critical pressuref = saturated liquidg = saturated gas

Figure 13 T-v diagram

143 Temperature-entropy diagram Temperature entropy (T-s) diagrams are widely used in thermodynamics because they are very useful in visualising irreversibilities of processes Constant volume constant pressure and constant enthalpy lines can be seen in T-s diagrams The slope of constant volume lines in single-phase regions are always steeper than those of constant pressure lines For superheated vapour states the constant enthalpy lines become almost horizontal as pressure is reduced The pressure change between states in this region can be neglected therefore entropy is the only function when temperature and gases behave more like ideal gases

Since the internally reversible heat transfer is expressed as int=

2

1int TdSQrev (see Equation 16)

the area under the curve on a T-s diagram represents revQint

Vertical lines on T-s diagrams represent processes undergoing isentropic (same entropy) compressionexpansion while horizontal lines inside the dome mean isothermal phase changes (vaporisationcondensation)

s

T

Vapour

p=constv=const

h=constp=const

v=const

Liquid-vapour

Criticalpoint

Liquid

Figure 14 Temperature-entropy diagram

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144 Enthalpy-entropy diagram By means of an enthalpy-entropy diagram (h-s) commonly called Mollier diagram (see Figure 15) the two major properties of interest in the first and second law analysis of open systems are represented The change in enthalpy ∆h corresponds to a vertical line in the h-s diagram and is related to the work changes for turbines compressors etc in adiabatic steady-flow processes The change in entropy ∆s is represented in the diagram by a horizontal line and gives an idea of the irreversibility for an adiabatic process On an h-s diagram constant pressure and constant temperature lines are straight in the dome region In the superheated region constant temperature lines become horizontal meaning that enthalpy and temperature are directly proportional This is the region where the ideal gas model can be reasonably applied

s

h

Liquid Liquid-vapour

Criticalpoint

Vapour

p=const

p=const

T=const

T=const

x=quality

Figure 15 Enthalpy-entropy diagram

145 Property tables databanks and simulation programs For many substances associated with industrial processes properties can be presented in the form of tables They come from experimental data The most frequently listed properties in tables are specific volume internal energy specific enthalpy specific entropy and specific heat Property tables can be found in thermodynamic books and there is also an example in Annex 1 Due to the fact that in one-phase regions two intensive properties must be known to fix the state for superheated vapour and compressed liquid the properties v u h and s are listed versus temperature for selected pressures If there are no available data for a compressed liquid a reasonable approximation is to treat compressed liquid as saturated liquid at the given temperature This is because the compressed liquid properties depend on temperature more strongly than they do on pressure The so called saturation tables are used for saturated liquid and saturated vapour states Since in two-phase regions pressure and temperature are not independent one of the properties is enough to fix the state Therefore in saturation tables the properties v u h and s for saturated liquid and saturated vapour are listed either versus temperature or pressure In the case of a saturated liquid-vapour mixture an additional property called quality (x) must be defined Quality is defined as the vapour mass fraction in a saturated liquid-vapour mixture

(-) Equation 130

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Where mg represents the mass of saturated vapour and mf the mass of saturated liquid The properties of such a mixture are determined by the aid of the saturated tables and the calculated quality is as follows yav = yf+xyfg Equation 131 Where bull y calculated quality bull v specific volume bull u internal energy per unit of mass bull x quality bull yfg mixture of quality (gas and liquid) yfg = yg - yf Equation 132 Tables in the real world are not enough There is a strong need to have thermodynamic properties of many substances both pure and mixed In fact complex thermodynamic data banks and associated physical property models form the heart of any computer energy simulator The need is so important that inaccuracy or unavailable data may lead to the rejection of attractive energy conservation solutions Fortunately a considerable amount of databases and computer programs may be found in thermodynamic literature and on the market A problem arises in having the knowledge to select data with good criteria even if contradictory data are found Quality accurate and up-to-date information is in many cases critical This is a key issue when calculating mixture properties in which departure from non-ideal behaviour is common Some major data compilations can be found from the following sources bull the American Petroleum Institute API bull Beilstein Institute of Organic Chemistry BEILSTEIN bull Design Institute for Physical Property Data DIPPR of AIChE bull Deutsche Gesellshaft fuumlr Chemisches Apparatewesen Chemische Technik und

Biotechnologie eV DECHEMA bull Physical Property Data Service PPDS in the UK For instance DIPPR has a comprehensive pure component data compilation meanwhile a primary source of mixture data is DECHEMA Commercial simulation programs with extensive capabilities for calculating thermodynamic properties can be easily found Three of the most experienced programs are the trademarked ASPEN PLUS HYSIM and PROII However these computer packages may do more than what a common energy saving analyst needs to do or perhaps they perform in a less specialised way On the other side these programs are costly both in effort of handling and money for acquiring and maintaining Intermediate solutions that allow the analyst to compose their own simulating solutions and include pure substance properties are for instance EES Thermoptim and BBlocks Therefore the analyst must devote time in judging which is worth buying Starting from scratch is not very advisable in most cases

15 Identification of inefficiencies Mechanical thermal and chemical equilibrium conditions of a thermodynamic system also imply three causes of disequilibrium or inefficiencies (irreversibilities in thermodynamics) Mechanical irreversibilities are due to pressure changes and always appear in processes that involve friction Entropy generation and exergy destruction are always associated with mechanical irreversibilities the greater the pressure change the greater the irreversibility created within the system

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Thermal irreversibilities appear when there is a finite temperature change within the system as for instance in every heat exchanger The heat passes from a warm body to a cold one spontaneously thereby losing exergy Again the irreversibility produced increases with the temperature change Chemical irreversibilities are due to a chemical disequilibrium occurring in mixtures solutions and chemical reactions For example when water and salt are mixed exergy is destroyed This exergy loss is equivalent to the minimum work that has been previously needed to purify water in order to obtain the salt All atmospheric and water pollution effects are included here It is very easy to contaminate (mix) but a lot of exergy is needed to clean up The thermodynamic analysis of irreversible processes reveals that in order to obtain a good efficiency and save energy it is required to control and minimise all the mechanical thermal and chemical irreversibilities appearing in the plant Three case studies now follow throttling devices (see Section 151) focusing in mechanical irreversibilities heat exchanges (see Section 152) focussing on thermal irreversibilities and mixing processes (see Section 153) focussing on thermal irreversibilities and have been developed in order to illustrate the ideas and calculation methodologies for identifying and minimising irreversibilities

151 Case 1 Throttling devices Throttling devices are very common in industry and are used to control and reduce pressure mainly through valves Since the throttling process is isenthalpic (where the enthalpy up and down flows are equal) no energy is lost and according to the first law of thermodynamics its efficiency is optimal However this is a typical mechanical irreversibility which reduces pressure and increases the entropy of the fluid without giving any additional benefit Consequently exergy is lost and the fluid is less capable of producing energy in a turbine expansion process for instance Therefore if the point is to reduce the pressure of a fluid it is desirable to tend to isentropic expansions providing useful work as an additional result through turbines If this is not possible the working pressure should always be the highest possible because this will avoid the use of compressors or pumps for fluid transportation (additional useful energy) A very frequent practice in industrial installations is to keep the pressure at the inlet of the turbine at the design conditions This usually implies the use and abuse of admission valves to control the turbine According to the second law it is better to have flotation of the pressure specifications (sliding pressure) and to keep the admission valves completely open As a general recommendation valves should be sized as large as possible A satisfactory throttling process can be achieved with a pressure drop of 5 - 10 at maximum flow instead of 25 ndash 50 as it happened in the past where valves were small sized Of course the pump driving the fluid must be also sized according to the variable conditions Finally it must be stressed that pipes also act as throttling devices decreasing the pressure of the fluid flowing through them Therefore a good design with good materials and few obstacles such as unnecessary valves elbows bows etc will limit the exergy losses across the process In any case it is clear that an exergy accounting that considers all the energy levels existing in the plant must be performed because from the first law point of view irreversibilities are very difficult or impossible to identify

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Numerical example During a unit commissioning in a power plant a steam extraction coming from the high pressure turbine (P = 40 kgcm2 T = 350 ordmC) is used in order to feed a turbopump Since the turbopump operates at an inlet pressure of 8 kgcm2 the steam coming from the high pressure turbine must be throttled (see Figure 16) In the following thermodynamic example variables of the steam are evaluated at the inlet and outlet of the valve The process is sketched on the T-s and h-s diagrams (see Figure 17) and the exergy flow is obtained when the nominal flow is 45000 kgh

1 2

P1= 40 kgcm2

T1= 350 degCP2= 8 kgcm2

Figure 16 Steam throttling process

Solution The first law of thermodynamics reveals that the process is isenthalpic since no work or heat transfer is associated with the throttling process 0 = m1(h2-h1) gt h2 = h1 Equation 133 The specific enthalpy and entropy obtained through the property tables are bull At P1 and T1

o h1 = 309195 kJkg and s1 = 658 kJkg K bull At P2 and h2 = h1

o T2 = 319 ordmC o S2 = 730 kJkg K

S

T

T1

T2

s2s1

1

2

h = 309195 kJkg

h

1 2

Ss2s1

h1 = h2

Figure 17 T-s and h-s diagrams for the steam throttling process of the example

The specific flow exergy is calculated as e = h ndash T0s Equation 134

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Where T0 = 273 K and the potential and kinetic energy are considered negligible Hence e1 = 309195 ndash 273 x 658 = 129561 kJkg and e2 = 309195 ndash 273 x 730 = 109905 kJkg This process is completely irreversible (mechanical irreversibility) The exergy loss is obtained through an exergy balance to the system Since there is no heat or work transfer the exergy balance reduces to

152 Case 2 Heat exchangers Heat exchangers are devices where two streams exchange heat Every heat transfer is the result of a temperature difference and thus is always associated with entropy generation and exergy destruction Therefore there is a contradiction between the ideas of minimum exergy loss and maximum heat transfer efficiency (see Section 461) In a counterflow heat exchanger like the one shown in Figure 18 where a hot fluid at T1in is cooled down to T1out by releasing heat to a cold fluid that heats up from T2in to T2out therefore the exergy loss in the process is calculated as follows The change in kinetic and potential energy are usually negligible and no work interactions are present For a first approximation the pressure drop can also be considered negligible The irreversibility created in the heat exchanger is given by I = (e1in + e2in) ndash (e1out + e2out) = (h1in + h2in) ndash (h1out + h2out)

T1out T2out - T [(s1in + s2in) ndash (s1out + s2out)] = T0 [ m1Cp1ln T1in

+m2Cp2 ln T2in Equation 135

It can be demonstrated from the equation above that I is always positive and increases with the temperature differences at the inlet and outlet of the fluids in the counterflow exchanger and between the top and bottom in a parallel-flow one In any case a counterflow exchanger is always better than a concurrent one (parallel-flow) from the exergy point of view because exergy is always being giving off to a system at a similar temperature The irreversibilities taking place in heat exchangers are due to two factors heat transfer caused by the temperature difference and pressure loss associated with the fluid circulation Both fluid friction and irreversible heat transfer can be reduced decreasing the fluid flow However in order to obtain the same effect of heat exchange a larger transfer area is required ie larger heat exchangers must be designed The idea of extending the use of counterflow heat exchange to the whole installation ie extending it to all flows to be heated or cooled in the plant so that the temperature change through which heat must flow is reasonably low leads to the energy integration of processes and the use of energy cascades This is the philosophy of the pinch methodology developed for the integration of heat exchanger networks The integration can also be extended to power cycles heat pumps and refrigeration cycles in the most efficient way In summary this procedure assures the lowest steam consumption (or any another heat source) and the lowest cooling water (or any other cold source) under the thermodynamic and technical conditions that may be assessed

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Fluid T1in

Fluid T2in

Fluid T1out

Fluid T2out

Figure 18 Counterflow heat exchanger

Numerical example In a boiler reheater (see Figure 19) 1100000 kgh of steam is heated from 350 to 540 ordmC at a pressure of 40 kgcm2 The heat absorbed by the steam comes from the exhaust gases of a combustion process The average temperature where the heat transfer occurs is 1000 ordmC In Figure 110 the process is sketched on the T-s and h-s diagrams and the heat absorbed by the steam and exergy losses is determined

P1 = 40 kgcm2

T1 = 350 degC

Q

P2 = 40 kgcm2

T2 = 540 degC

Figure 19 Reheating process of a steam flow

Solution The energy balance of the system considered in Figure 19 is m (h2 ndash h1) = Q Equation 136 The specific enthalpy and entropy obtained through the property tables is bull At P1 and T1

o h1 = 309195 kJkg and o s1 = 658 kJkg K

bull At P2 and T2

o h2 = 353085 kJkg and o s2 = 721 kJkg K

Hence the heat transfer obtained is Q = 11100000 x (353085 ndash 309195) = 4389 kJkg = 4827 x 106 kJh T-s and h-s diagrams are shown in Figure 110

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S

T

S1

1

2

S2

P = 40 kgcm2

h

12

SS1 S2

P = 40 kgcm2h1

h2

Figure 110 T-s and h-s diagram for the steam reheating process of the example

The specific flow exergy is calculated as e= h ndash T0s Equation 137 Where T0 = 273 K and the potential and kinetic energy are considered negligible Hence e1 = 309195 ndash 273 x 658 = 129561 kJkg and e2 = 353085 ndash 273 x 721 = 156252 kJkg The exergy loss generated is given by

153 Case 3 Mixing processes The mixing of fluids with different compositions or temperatures is another process very common in industry This concept includes tempering processes for temperature control mixing processes for quality control substance purifying processes distillation etc For example an adiabatic mixture of two different ideal gases flows at the same temperature and pressure and n1 and n2 equals the number of moles of each flow The generation of entropy in the mixing process corresponds to the sum of the entropy increase of each gas due to their expansions from P to their new partial pressure of the mixture Hence

summinus=

minus

+= ii xxR

PP

RnPP

Rnnn

lnlnln1 22

1

1

2

1

σ (JK) Equation 138

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Since Pi = xiPi and sum=

i

ii

n

nx

the exergy loss is calculated as follows I = T0σ = - RT0sum xi ln xi (J) Equation 139 This expression is always positive and symmetrical with respect to the value xi = 05 It tends to zero when xi tends to zero (maximum purity) Figure 111 shows IiRT0 versus the molar fraction of one component in the mixture xi The maximum exergy is reached when xi = 0 butunder these conditions it is relatively easy to separate both components As the mixture is being purified the exergy loss per mol of the separated component increases

08

Mole fraction of one component x

02 100806040

02

04

06

Ixiln xi

x

R=minusΣ

xilnximinus

Figure 111 IiRT0 versus molar fraction of one component in the mixture

For the considered binary system the irreversibility is equal to

[ ])1ln()1(ln0 xxxxRTI minusminus+minus= and

minus

minus=)1(

ln0 xxRT

dxdI

Equation 140 Some of the values of this derivative are presented in Table 11

x IRT0 (1RT0) dIdx 010 0325 220 001 0056 496

10 - 3 791 x 10 - 3 691 10 - 4 102 x 10 - 3 921

Table 11 Some values of the derivatives

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This derivative indicates the work required to improve the purity of the product and the easiness to pollute In other words the exergy value of the product is related with this derivative Multicomponent mixtures behave in the same way The maximum value of the function -sum xi ln xi that takes place for equimolar mixtures is shown in Table 12

N - sumxilnxi N - sumxilnxi2 0693 5 1609 3 1099 7 1946 4 1386 10 2302

Table 12 Maximum values for mistures

As the number of components of the mixture increases the irreversibility effects become more dramatic These ideas lead to a set of recommendations for energy saving in mixing processes Firstly and most importantly mixing processes must be avoided whenever it is possible Obtaining high quality steam or a very pure substance requires a great amount of exergy that is mostly lost when mixed with a lower quality flow (even if the energy loss is zero) Secondly the quality specifications of a certain product must not be exceeded and above all once they are exceeded they should never be mixed with lower quality flows This way if a product with 01 purity is mixed equimolarly with another of 1 purity the final product will have 055 purity but the exergy value of this product will decrease

significantly with respect to the individual flows since this is related with the derivative dxdI

and not with the mean composition value Some quality specifications of products should be reviewed and should be made lsquosofterrsquo if possible This is something basic in the chemical industry in which it is very common to find partially refined matter mixed with over purified products or mixtures of products coming from two parallel units for achieving an average purity Numerical example A steam flow at a pressure of 180 kgcm2 and a temperature of 550ordmC is mixed with saturated liquid at 180 kgcm2 in order to reach the temperature design specifications of a certain equipment (see Figure 112) In Figure 113 the final temperature of the mixture and the exergy loss is determined when the mass flow of steam is 1100000 kgh and of the liquid 30000 kgh

Hot stream (1)

Cold stream (2)Mixed stream (3)

P3 = 180 kgcm2

P1 = 180 kgcm2 T1 = 550 degC x = 0

P2 = 180 kgcm2 x = 0

Figure 112 Mixing chamber of two flows

Chapter 1

24 Version April 2006 SSEIPPCBENE_Draft_1

Solution The mass balance of the system is m1 + m2 = m3 Equation 141 Since there is no work or heat transfer to the process and the kinetic and potential energy can be assumed to be zero the energy balance reduces to m1 h1 + m2 h2 = (m2 + m1) h3 Equation 142 At P1 and T1 the specific enthalpy and entropy obtained through the property tables is h1 = 34142 kJkg and s1 = 641 kJkg K respectively For the saturated liquid at the cold stream (2) only one property (pressure in this case) is needed to fix the state h2 = 171706 kJkg and s2 = 385 kJkg K From the energy balance applied above

At the mixed stream (3) with h3 and P3 T3 = 534 ordmC and s3 = 635 kJkg K The change in specific enthalpy and entropy can be obtained with the help of the property tables in Annex 1 The specific flow exergy is calculated as Equation 137 where T0 = 273 K and the potential and kinetic energy are considered negligible Hence e1 = 166452 kJkg e2 = 66667 kJkg and e3 = 163455 kJkg The irreversibility is obtained through the exergy balance I = m1(e1 - e3) + m2 (e2 ndash e3) =gt I = 11 x 106(166452 ndash 163455) + 30 x 103(66667 ndash 163455) = 376 x 106 kJh = 104 MW The T-s diagram is shown in Figure 113

S

T

T1

T3

T2

S2 S3 S1

P = 180 kgcm2

1

2

3

Figure 113 T-s diagram for the mixing process of the example

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 25

Remarks for all three case studies Irreversibilities are the effects of any improvable energy system Besides avoiding finite pressure temperature andor chemical potential differences the causes of poor energy design come from decoupling supply and demand Time plays an important role in energy efficient systems Energy systems spontaneously decrease its pressure temperature and chemical potential to reach equilibrium with its surroundings To avoid this there are two strategies bull to couple energy donors with energy acceptors immediately bull storage to enclose a system within rigid walls for pressure adiabatic walls for temperature

andor to confine the chemical systems into metastable states In other words confine the systems into reservoirs that maintain their intensive properties constant with time

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 27

2 ENERGY EFFICIENCY [4 Cefic 2005] [5 Hardell and Fors 2005] This chapter deals with definitions of energy efficiency relevant for industry and how to develop indicators to monitor energy efficiency Furthermore it deals with different aspects which influence energy efficiency some of which a company has control over and some of them not It also gives examples on how different system boundaries influence energy efficiency

21 Definitions of energy efficiency Defining energy efficiency is a complex task It is not possible to present a solution that will fit in all cases and will satisfy all stakeholders When the term energy efficiency is used the meaning of the term is usually not defined When it is defined the meaning depends on the context in which it is used The main reason is that everyone does not deal with energy in the same way or use the same system boundary It may be simple to describe the meaning of energy efficiency for a single component or a subsystem whereas some difficulties arise as soon as it comes to definitions of energy efficiency for complex industrial plants Because energy efficiency means different things for different stakeholders clarification on what energy efficiency means in this document is required First a distinction needs to be made between energy efficiency at the macro level (eg national) and at the micro level (eg company level) In this document only the latter is discussed (see Scope) Furthermore the main focus of this document is on physical energy efficiency although economic efficiency will be touched on as well In this document energy efficiency is dealt with from an industrial perspective within the installation boundaries without considering a productrsquos life cycle This is in line with the IPPC Directive which deals with production and not with products The fuel by which energy is produced is also not considered in this document There is not a commonly agreed definition of energy efficiency in the EU The IPPC Directive does not define energy efficiency either However it requires IPPC installations to be driven energy efficiently and energy efficiency is part of the BAT consideration and should be addressed in permit application and permit conditions Thus to fulfil the requirements of demonstrating energy efficiency good indicators are needed Energy efficiency has been defined eg in the following ways bull a ratio between an output of performance service goods and energy and an input of

energy A definition can be found in the Common Position No 342005 on Energy and Use Efficiency and Energy Service Directive (9376EEC) where energy efficiency is defined According to this definition the replacement of other fuels by renewables does not improve energy efficiency Also energy efficiency improvement is defined in the same Common Position as an increase in energy end-use efficiency as a result of technological behavioural andor economic changes These definitions have a broader scope than just energy efficiency in industry

bull to obtain an unchanged output value at a reduced energy consumption level (the Swedish Energy Agency)

bull to obtain an increased output value with unchanged energy consumption or to obtain an output value that in relative terms surpasses the increase in energy consumption (the Swedish Energy Agency)

bull the amount of energy consumed per unit of productoutput bull the amount of energy consumed per unit of feedstock

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28 Version April 2006 SSEIPPCBENE_Draft_1

bull energy consumption per unit of product where the consumption of energy is from energy carriers This does not refer to non-energy consumption in the form of feedstocks The energy consumption from secondary energy carriers will be allocated back to the net caloric value (lowest combustion value) of the primary energy carriers Net electricity purchases will be offset at a generation yield requiring the approval of the independent authority When this is used the determination of the proportion of feedstock in energy consumption for each relevant processing plant typically requires the approval of the independent authority [13 Dijkstra ]

In industry the most commonly used definition for energy efficiency is the amount of energy consumed per unit of productoutput which can also be called specific energy consumption or energy intensity factor Improving energy efficiency therefore means reducing the amount of energy required to produce a unit of product This definition will mainly be used in this document The definition looks deceptively simple However once one tries to quantify the concept for monitoring processes experience shows that a framework is required to better define and measure energy efficiency This framework is provided in Section 22 The definition as such does say much about the issue of whether energy is used or produced efficiently To be informative and useful energy efficiency must be compared to something (another unit company over time) and for comparison there must be rules In the case of comparing energy efficiency it is especially important to define system boundaries so that all users are speaking equally As it simplest the definition neither takes a view on how efficiently energy is produced nor how lsquowastersquo energy is used after the system boundary Eg these issues and several others must be decided transparently so that it is possible to evaluate improvements of energy efficiency All these issues will be dealt with in Section 23 Energy efficiency is considered mainly from the perspective of a single industrial company and from the perspective of a production site grouping several production processesunits However the best energy efficiency for a site is not always equal to the sum of the optimum of the energy efficiency of the contained production processesunitscomponents De-optimisation of the energy efficiency of one or more production processesunits may be required to achieve the optimum energy efficiency of the site That is why it is crucial to understand how the definition of a system boundary will influence energy efficiency Furthermore by extending system boundaries outside a companyrsquos activities and by integrating industrial energy production and consumption with the needs of community outside the site the total energy efficiency could be increased eg by providing low value energy for heating purposes in the neighbourhood

22 Energy efficiency indicators in industry Definitions used for energy efficiency were discussed in Section 21 This section express how energy efficiency and indicators are developed for individual industrial production processesunitssites It explains what and how to consider the relevant issues The main target of the indicators is to make a self analysis possible or to compare units to other units or to other companies The importance of clear decisions of system boundaries energy vectors (energy flows) and the way to deal with other related issues (eg wastefuel electricity conversion factor) is expressed

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 29

221 Production processes A production processunit is a process which takes in one or more feeds and converts these into one or more valuable products and in doing so consumes energy Examples of production processesunitssites are bull a gas powered electricity plant takes in gas as its feedstock and the product of this

production process is electricity The energy used is the energy available within the gas Electricity can be also produced in a combined heat and power plant and then the total efficiency is of course better

bull a refinery takes in crude oil and transforms this into gasoline diesel fuel oil and a number of other products A part of these products is burned internally to provide the necessary energy for the conversion process Usually some electricity also needs to be imported unless a cogeneration plant is installed within the refinery in which case the refinery may become a net exporter of electricity

bull a steam cracker takes in liquid and gaseous feeds from a refinery and converts these to ethylene and propylene plus a number of by-products Part of the energy consumed is generated internally in the process supplemented by imports of steam electricity and fuel

bull the feeding to the rolling mill in a steel works consists of approximately 2 decimetres thick flat steel plates that are to be rolled out to bands with a thickness of a few millimetres The rolling mill consists of furnaces rolling mill equipment cooling equipment and support systems including pumps fans hydraulics and lubricating systems lights a mechanical workshop staff space changing rooms etc See Section 244

After defining energy efficiency indicators it will be possible to measure and evaluate the changes in efficiency eg demonstrate that energy is usedproduced efficiently

222 Energy intensity factor and energy efficiency index To show how energy efficiency is developed over time in a company or to make benchmarks between different companies the following indicators may be used the energy intensity factor and the energy efficiency index The energy intensity factor is often called the specific energy consumption and it expresses the amount of energy used to produce the given product(s) How to develop the structure to define energy efficiency and indicators for production units and sites will be expressed in Sections 223 and 224 The main purpose of the energy efficiency indicators is to be able to monitor the progress of the energy efficiency of a given production unit over time and to see the impact of energy efficiency improvement measures and projects on the energy performance of the production processunit In its simplest form the energy intensity factor (EIF) can be defined as EIF = (energy imported ndash energy exported)products produced Equation 21 EIF is a number with dimensions eg GJtonne The energy efficiency index (EEI) is defined by dividing a reference energy intensity factor by the energy intensity factor EEI = EIFrefEIF Equation 22 EIFref can either be a reference number which is generally accepted by the industry sector to which the production process belongs or it can be the energy intensity factor of the production process at a given reference year

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The energy efficiency index is a dimensionless number and can be used to for instance measure the progress on energy efficiency of the given process over time EIF is a number that decreases with increasing energy efficiency whereas EEI is a number that increases Energy management therefore targets the lowest possible EIF and the highest possible EEI EIF shows how much energy is used to produce given products but without any reference to previous achievements That is why the value of one single figure alone is not very big EEI shows the trend and is more useful For monitoring purposes the time frame on which the energy efficiency is calculated is best taken for long periods (eg months or years) For example on an hourly basis the energy efficiency indicator may show large fluctuations for a continuous process and it would actually not even make sense for a batch process These fluctuations are smoothed out on longer period basis While Equation 21 and Equation 22 look deceptively simple experience shows that the definitions leave room for interpretation and issues like system boundaries energy vectors and how to deal with different fuels must be defined and decided before use them especially when comparing one production process with another In addition to the two main indicators dealt with here there are also other indicators and sub-indicators One example of a sub-indicator is a pressure level in a compressing system which clearly indicates energy efficiency

223 Energy efficiency in production units In the following two examples the concepts of EIF and EEI are illustrated Example 1 Simple case Figure 21 shows an example of a simple production unit For transparency reasons the handled process will be without energy exports and with only one feedstock and one product The production process makes use of steam electricity and fuel

SteamEsin

Productionunit

Main product P

Fuelimport

Efin

ElectricityEein

Feed F

Figure 21 Energy vectors in a simple production unit

The EIF of this process is given by

Equation 23

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 31

Where bull Esin energy supplied to the process via steam to produce an amount of product P bull Eein energy supplied to the process via electricity to produce an amount of product P bull Efin energy supplied to the process via fuel to produce an amount of product P In Equation 23 it is essential that the various energy vectors (energy flows) are expressed as primary energy and on the same footing For instance 1 MWh of electricity requires more energy to produce than 1 MWh of steam as electricity is typically generated with an efficiency of 35 ndash 55 and steam with an efficiency of 85 - 95 The energy use of the different energy vectors in Equation 23 therefore needs to be expressed in primary energy This includes the efficiency to produce that energy vector (see also Section 232) An example of a calculation of energy efficiencyAssume that to produce 1 tonne of product P1 the following energy vectors have to be used bull 001 tonne of fuel bull 10 kWh of electricity bull 01 tonne of steam Now assume further the following bull lower calorific value of fuel = 50 GJtonne bull efficiency to produce electricity = 40 bull steam is generated from water at 25 degC bull the difference between the enthalpy of steam and the enthalpy of water at

25 degC = 28 GJtonne bull steam is generated with an efficiency of 85 To produce 1 tonne of product P1 the energy consumption is as follows bull Efin = 001 tonne fuel x 50 GJtonne = 050 GJ bull Eein = 10 kWh x 00036 GJkWh x 104 = 009 GJ bull Esin = 01 tonne steam x 28 GJtonne x 1085 = 033 GJ The EIF of this process is then given by bull EIF = (050 + 009 + 033) GJtonne = 092 GJtonne For the concept of EEI assume that this is the reference EIF Now assume that the plant carries out a number of energy efficiency improvement projects so that a year later the energy consumption of the production process has become bull 001 tonne of fuel bull 15 kWh of electricity bull 005 tonne of steam As a result of these energy efficiency improvement projects the new EIF of the process is bull EIF = (05 + 0135 + 0165) GJtonne = 08 The EEI of this process is then bull EEI = 09208 = 115 This indicates that the energy efficiency of the production process has increased by 15

Chapter 2

32 Version April 2006 SSEIPPCBENE_Draft_1

Example 2 More general case Figure 22 deals with a more general case when there is both export of energy and internal recycling of fuel The general case presented here is believed to be sufficiently flexible to be applicable for most industries

Production unit

Recycled fuel Efrec

Main products P1

Other products P2

ElectricityEeout

OtherEoout

Wastelosses W (incinerationflareeffluentto environment)

SteamEsout

Feed F1

Feed Fn

SteamEsin

ElectricityEein

OtherEoin

Fuel importEfin

Recycled fuel Pf

Figure 22 Energy vectors in a production unit

The energy intensity factor EIF of this process is then defined as follows

Equation 24

This generic formula can be applied to each production processunit or site but its various components have to be adapted to each specific production processunitsite The unit of this indicator is (unit of energy)(unit of mass) usually GJt product or MWht product Some consideration to take into account when applying Equation 24 (some also applicable to Equation 23) are described in the seven points follow

1 Feedproduct flows (Fi Pi)

In the horizontal direction the mass-flow of the products is shown in Figure 22 The feeds Fiare the different raw materials used to produce the product The products coming out of the process are split into main products P1 and by-products These by-products are split in two fractions a fraction which is recycled as fuel (Pf) and the remaining other products (P2) An example that can be derived from the petrochemical industry is the ethylene steam crackers where energy consumption can be expressed in GJ per tonne ethylene in GJ per tonne olefins (ethylene + propylene) or in GJ per tonne of high value chemicals (olefins + butadiene + benzene + pure hydrogen) This approach is also valid in the chlor-alkali field where consumptions are usually related to the tonne of Cl2

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 33

2 Energy vectors flows (Ei)

Energy vectors are different types of energy flows going and going into the unit In the vertical direction of Figure 22 the energy imported and the energy exported which is used elsewhere are shown The following energy vectors are considered bull Es = steam andor hot water bull Ee = electricity to the process bull Ef = fuel (gas liquid solid) A split is made between the externally purchased fuel and the

fuel which is internally recycled in the process bull Eo = other this covers any utility which requires energy to be produced Examples are hot

oil and cooling water This cooling water requires energy to produce it (energy is required to operate the pumps circulating cooling water and the fans on the cooling towers)

It is important that on the export side only those energy vectors which are lsquousefullyrsquo used after a main processunit in another process are counted In particular the energy associated with cooling of the product to cooling water or air can never be included as the lsquoenergy outrsquo in Equation 24 Energy is consumed to produce cooling water (operation of pumps and fans) but this energy is not always included which is similar to compressed air and N2 Heat losses to the air should also never be counted

3 Different steam levels (Es)

The production plant could be using or producing more than one type of steam (different pressures andor temperatures) Each of these steam levels needs to be included in the term EsHot water if used (or produced and used by another production plant) should be included Each level of steam may have to produce its own efficiency factor

4 Waste flows (W) Each process will also generate an amount of waste products These waste products can be solids liquids or gaseous and may be bull disposed of to landfill (solids only) or by incineration bull be used as fuel (Pf) or bull recycled The relevance of this waste stream will be discussed in more detail in Section 232

5 Fuel or product or waste (E0 Pf)

In Figure 22 fuel is not shown as an exported energy vector The reason for this is that fuel is considered as a product rather than an energy carrier and that the fuel value which would be attributed to the fuel is already present in the feed going to the production unit This philosophy is standard within refineries and the chemical industry Other industries may apply different practices For instance in the chlor-alkali industry some operators count the H2 (a co-product of the Cl2 and NaOH produced) as an energy vector independent of whether this H2 is subsequently used as a chemical or as a fuel (only the H2 flared is not counted) It is therefore important to establish the rules for defining energy efficiency specific to a given industrial sector such as feeds products energy carriers imported and energy carriers exported

Chapter 2

34 Version April 2006 SSEIPPCBENE_Draft_1

6 Time frame The energy intensity factor can be calculated on any desired time frame (hour week month year) The preferred time basis to compare energy efficiency is however a month or a year as this will better capture and level recurring energy consuming disturbances in the process For instance a process may have low relative energy consumption during normal operation but may have frequent shutdowns and restarts related to fouling which consume significant amounts of energy the monthly or yearly energy intensity factor will better capture the effect of these recurring events which measure the energy efficiency of the process

7 Measured or estimated Equation 24 assumes that the different energy vectors to the production process are known However for a typical production process the different utility consumptions (eg cooling water nitrogen steam tracing steam to a turbine electricity) are not always measured Often only the major individual utility consumptions of the production process are measured in order to control the process (eg steam to a reboiler fuel to a furnace) The total energy consumption is then the sum of many individual contributors of which some are measured and some are lsquoestimatedrsquo Rules for estimation must be defined and documented in a transparent way

224 Energy efficiency of a site Complex production sites operate more than one production processunits To define energy efficiency of a whole site it has to be divided into smaller units which contain process units and utility units The energy vectors around a production site can be schematically represented as in Figure 23

Unit Unit

Unit Utilities

Energy imported

Products out

Energy exported

Feeds in

Figure 23 Inputs and outputs in a site

A production site may make different types of products each having its own energy intensity factor It is therefore not always easy to define a meaningful energy efficiency indicator for a site The indicator may be the following

Equation 25

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 35

An issue which needs to be addressed when dividing the production sites into production units (see Section 232) is whether the utility centre should be seen as a separate production unit Usually this is the case as the utility centre produces utilities for more than one production unit The next issue is whether this utility centre will have its own energy consumption or whether it just converts one energy vector in another The utility section in itself may be divided in several sections for instance it could be divided in a part related to the storage and loadingunloading area a part related to hot utilities (steam) and a part related to cold utilities (cooling water N2 compressed air) The following equation should always be verified

sectionutility byusedEnergy PEIF site by the usedEnergy units i

i +lowast= sum=

iEquation 26

For implementation of energy management in the site it is essential to divide the site into its production units including the exact system boundary of these production units to clearly define the energy flows in and out of the site and between the different production units (Unit boxes in the Figure 23) This then clearly defines the way in which the energy efficiency of a given production process is calculated This break-up of a site into production units will depend on the complexity of the production site and has to be decided ndash in every single case ndash by the operator responsible

23 Issues to be considered when defining energy efficiency indicators

In Sections 223 and 224 it was discussed how to develop energy efficiency for a production unit and for a site Sections 231 and 232 discusses some important issues that can be decided by the company and which should be taken into account in the definition of energy efficiency and indicators Section 233 discusses structural issues that are not typically under the decision of a single company but influence the definition of energy efficiency

231 System boundaries

2311 Definition of the system boundary It is most important to clearly define the system boundaries of a processunit when defining the efficiency of a processunitsite (eg whether the boilers are included in the main process unit or whether they are independent) When this has been decided once the same decisions will always apply Steam boilersSteam boilers may be included as an individual unit or as a part of process unit For instance on small sites with only one production process on the site the steam boiler will often be included in the system boundary of the production process The primary energy source in this case will be the fuels burned on the steam boiler In contrast on large sites which often have common boilers for all processes the steam boiler will often be left out of the system boundary of the production process and the main energy carrier will be steam rather than fuel

Chapter 2

36 Version April 2006 SSEIPPCBENE_Draft_1

Auxiliary unitsAnother issue is when auxiliary units are included in the system boundary An example is the case of gasoline hydrotreaters in a steam cracker Gasoline is a co-product of a steam cracker (hence is counted in P2 rather than P1 in Figure 22) Before it can be added to the gasoline pool it needs however to be hydrotreated to saturate the olefins and diolefins present and to remove the sulphur components Most operators would treat the gasoline hydrotreater as a separate unit of the steam cracker However in some sites the gasoline hydrotreater is integrated to the cracker so that for simplicity purposes it is sometimes included within the cracker system boundary Not surprisingly those crackers which include the gasoline hydrotreater in their system boundary will tend to have higher energy consumptions than those which do not This of course does not imply that their energy efficiency is lower Components and sub-systemsIn Section 2312 there are several examples of how the definition of a system boundary influences the efficiency

2312 Examples of system boundaries In this section it will be illustrated how the efficiency changes when a system boundary is extended from a single component to a unit The section deals with single components subsystems or aggregate systems ie equipment types that are frequently to be found in the manufacturing and the process industries A number of examples have been chosen to illustrate the complications that may arise when trying to define the results of different measures for energy efficiency improvements Starting with the consideration of the efficiency of components and subsystems the further discussion takes into account what happens when a lot of subsystems are interconnected as is the case in industrial plants System 1 Old electric motorAn electric motor has been chosen as an example to show the differences in system boundaries In the company concerned an overview was made of existing motor drives and it was found that this motor was very old (see Figure 24) The electric power was 100 kW The efficiency of the motor was 90 and accordingly the mechanical output power was 90 kW

Old electric motor

System boundary

Electric power 100 kW

Mechanicalpower (90 kW)

Power input (100 kW) Output value (90 kW) Efficiency (90 )

Figure 24 System boundary ndash old electric motor

System 2 New electric motorTo improve the efficiency the motor was replaced by a high efficiency motor The effects of this change are shown in Figure 25

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 37

New electric motor

(937 )

Electric power 96 kW

Mechanicalpower (90 kW)

System Boundary

Power input (96 kW) Output value (90 kW) Efficiency improvement (4 kW)Output unchanged

Figure 25 System boundary ndash new electric motor

The electric power needed to produce the same output power 90 kW is now 96 kW due to the higher efficiency of the new motor The energy efficiency improvement is thus 4 kW

System 3 New electric motor and old pumpAs shown in Figure 26 an electric motor is used to operate a pump that provides cooling water for a cooling system The combination of pump and drive is regarded here as one component The output value of this component is the hydraulic power in the form of cooling water flow and pressure Due to the low efficiency of the pump the output value is limited to 45 kW

New electric motor and old pump

(937 )

Electric power 96 kW

System boundary

Power input (96 kW) Output value (45 kW) Efficiency (47 )Output unchanged

Hydraulic power (45 kW)

Cooling water

(50 )

Figure 26 System boundary ndash electric motor + old pump

System 4 New electric motor and new pumpSix months after the replacement of the motor it was found to be necessary to replace the old pump by a new one thereby increasing the pump efficiency from 50 to about 80 The result of the replacement is shown in Figure 27

Chapter 2

38 Version April 2006 SSEIPPCBENE_Draft_1

New electric motor and new pump

(937 )

Electric power 90 kW

System boundary

Power input (90 kW) Output value (67 kW) Efficiency (75 )

Hydraulic power (67 kW)

(80)

Figure 27 System boundary ndash electric motor + new pump

The efficiency of the new equipment is evidently much higher than the previous one The hydraulic power has increased from 45 to 67 kW What improvement of energy efficiency has been attained if one Figure 26 and Figure 27 are compared A reduction of the input power by 6 kW Or an increase of the hydraulic power by 22 kW Or the sum of these changes ie 28 kW As was indicated in Figure 26 the cooling system worked properly even at a hydraulic power of 45 kW What is the benefit of an increase of the hydraulic power by 50 to 67 kW Does it mean that the pumping losses have now been transferred to a control valve and the piping system That was certainly not the intended aim of the replacement of components

System 5 New electric pump new pump and constant output valueAn unbiassed study of the cooling system might have shown that a hydraulic power of 45 kW was sufficient and in this case the shaft power can be estimated at 4508 = 56 kW The electric power needed to drive the motor would then be about 560937 = 60 kW See Figure 28

New electric motor and new pump with constant output value

(937 )

Electric power 60 kW

Power input (60 kW) Output value (45 kW) Efficiency (75 )

Hydraulic power (45 kW)

(80 )

Figure 28 Electric motor + new pump with constant output

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 39

In this case the power input was 40 kW lower than before see Figure 24 The question is whether it could have been possible to reduce the size of both motor and pump without harmful effects on the cooling Or could it even be possible to reduce the required hydraulic power to eg 20 kW These types of questions are rarely brought up for discussion and even so no answers will generally be given Still in many cases asking good questions may be the starting-point for profitable improvements to energy efficiency

System 6 System 5 coupled with an heat exchangerIn Figure 29 the system boundary has been extended and the subsystem now includes a new motor a new pump and an old heat exchanger for the cooling process The process cooling power is 13000 kWth (th = thermal)

Hydraulicpower (67 kW)

New electric motor new pump and old heat exchanger

System boundaryCooling

water

(80)Heat from process

(13000 kWth)

Electric power 90 kW

Control valve

13000 kWth

Power input (90 kW) Output value 1 Process cooling 13000 kWth

Output value 2 Hydraulic power 67 kW

Figure 29 New electric motor new pump and old heat exchanger

The output value is represented by the removal of process heat and hydraulic power due to increased water flow and pressure How is the efficiency of the entire system to be defined And how will the efficiency be changed if the cooling needs decrease to 8000 kW caused by a reduction of the utilisation of production capacity

System 7 System 6 with recovery of heatDue to environmental concerns a decision was taken by the company to reduce the emissions of carbon and nitrogen dioxides by recovering heat from the cooling water thereby reducing the use of oil in the heating plant (see Figure 210)

Chapter 2

40 Version April 2006 SSEIPPCBENE_Draft_1

Electric power 90 kW

System boundary Coolingwater

(80)

Power input 90 kW

Control valve

Output value 1 Process cooling 8000 kWth

Heat from process 8000 kWth

Heat recovered replacing fuel oil for heating of premises 4000 kWth

Hydraulic power67 kW

unused heat4000 kWth

Output value 3 Hydraulic power 67 kWth

8000 kWth

Output value 2 Recovered heat 4000 kWth

Figure 210 New electric motor new pump and two heat exchangers

It is evident that the heat recovery arrangement represents an increased output value of the subsystem To estimate the value of the heat recovery in more detail the oil-fired heating plant needs to be considered as well The value of the reduction of the oil consumption the reduction of emissions and the decreasing heat recovery from hot flue-gases from the heating plant need to be taken into account In this case like in most others the subsystems are interconnected which means that the energy efficiency of one subsystem often has an influence on the efficiency of another

2313 Some remarks on system boundaries bull the importance of defining system boundaries is emphasised There are no general rules to

be applied but the lack of definitions can easily cause ambiguities in the understanding of what is included in a system

bull the more narrow the system boundary the easier will it be to state the energy consumption and the output value (See Figure 24 and Figure 25) In complex systems difficulties will often arise when trying to add up different energy savings

bull when the system boundaries are extended (see Figure 26 Figure 27 and Figure 28) to include a pump the output value will increase considerably when installing a new and modern pump The efficiency will increase from 47 to 75

bull in Figure 29 the system boundary has been further extended The major output value is represented by the cooling of process heat In comparison the produced hydraulic power is of minor importance

bull in Figure 210 the cooling power has been reduced considerably entailing reduced production The reason for this is a lower customer demand or changed market conditions Furthermore heat recovery has been introduced The input power to the motor is identical in Figure 29 and Figure 210 but in reality it would be lower in Figure 210 as the cooling demand has been reduced

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 41

232 Other items to be decided by the company

1 Denominator in energy intensity factor and energy efficiency index In most cases it is quite clear that the denominator is the productoutput However sometimes it may be relevant to use the feedstock as a divisor and furthermore in cases when several products are produced over time it should be considered which is the most relevant denominator to achieve the best results bull products co-products and feedstock - in the simplest case the production unit will produce

one main product which can then be used as the divisor In some cases a number of equally important products or a number of important co-products can be produced Where appropriate the sum of these products can be used as the divisor Otherwise the boundaries have to be taken in order to have a meaningful consistence between the energy balance and the products balance

bull in some cases it may be more meaningful to use the amount of feedstock as the divisor This is often the case for mineral oil refineries where the number of product streams is high (eg typically 5 to 7 stream products for an atmospheric crude distillation) and constant and the number of feed streams is low (typically one stream) This divisor is recommended if the energy consumption of a given production unit is determined mainly by the amount of feedstock taken in and less by the amount of product coming out which could be the case when the latter quantity depends strongly on the quality of the feedstock However using feedstock as a divisor cannot take into accout a lost of efficiency of the process

bull several products in batch or in campaigns - special attention should be paid to sites making several different products either in batch or in campaigns As an example a polymer plant could make polymer grades A B and C These grades are made in campaigns for instance grade A may be produced for two weeks then grade B for four weeks and then grade C for one week before producing grade A again The market may determine the production quantities of these various grades and the relative fractions of these grades may vary from year to year Each grade may have its specific energy consumption for instance grade A may consume more energy per unit of product than grade B which itself consumes more energy than grade C To be able to monitor the energy efficiency indicator of the process it may be useful to define a reference energy efficiency indicator per grade (based on the average energy consumption for that given grade) The relevant energy efficiency indicator over a specific period could then be defined

period during produced Cand BAproducts ofSumconsidered periodover unit productionbyusedEnergy

irefCBAi

i EIFxEEI

lowast=

sum= Equation 27

Where xi is the fraction of grade i on total product produced over the given period and EIFrefi is the reference energy efficiency factor for grade i (calculated for instance by averaging the energy efficiency indicator over a reference period when only grade i was produced This is also applicable when the production plant produces only one product but with different specifications and each having a different energy usage

Chapter 2

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2 Internal production and use of energy In several processes (eg refineries black liquor in pulp and paper plants) fuel that is produced in the process is consumed internally It is essential that the energy in this fuel is taken into account when looking at the energy efficiency of a process Indeed as shown in Section 222 refineries would have very low energy consumptions as all liquid and gaseous fuels (unless natural gas is used) consumed in the refining process are generated internally from the crude oil imported Typically 4 ndash 8 of the crude oil imported is converted into fuels which are consumed internally The only energy vector imported is then electricity (which is a small contribution compared to fuels burned) When the refinery is moreover equipped with a cogeneration facility it may be exporting electricity while increasing the internal fuel consumption According to the Equation 21 and Equation 22 a refinery equipped with a cogeneration facility would become a net energy producer Clearly this does not seem a good reflection of reality as common sense suggests that refineries consume significant amounts of energy Being aware of the above-mentioned issues it must be stated that system boundaries and energy vectors can be freely chosen but once defined for a specific plant these should be binding

3 Waste and flare recovery WasteAny process generates a quantity of solids liquid andor gaseous waste Often this waste will be recycled as a material or exported to an external incineration company Consider the case where the waste is sent to an external incinerator company Now assume that the production site finds a way to use this waste internally eg as fuel on its boilers or its furnaces Some reflection is required as to whether this improves the energy efficiency of the production unitsite bull the internal use of this waste reduces the need for external fuels but the overall energy

consumption still stays the same bull on the other hand the incinerator company may have an installation where the fuel value of

that waste is recovered via the production of steam In this case the rerouting of the waste stream for use as an internal fuel rather than sending it to an incinerator company may not result in any overall improvement of the energy efficiency when looking at the total picture of production company + incinerator company

In the proposed Equation 24 no credit is given for recovering waste as fuel However the switch from external incineration to internal use may be driven by commercial conditions Some industrial sectors may however have a different point of view and valorise the internal use of waste in their energy efficiency It is important that each industrial sector andor company clearly defines the standard practice applied

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FlareAny gas sent to flare is burned without recovery of any of the calories contained in the flare gas The reason is that the flare is really a safety device and well maintained operated and designed sites will have under normal operating conditions a small to negligible flow to flare Most sites will however have a constant small flow to the flare due to eg leaking relief valves and venting due to loadingunloading operations of storage tanks Some sites have therefore decided to install a flare gas recovery system which recovers this small flow and recycles it to the site fuel gas system Now suppose a production process which previously did not have a flare gas recovery system decides to install one This will reduce the external consumption of fuel gas whereas the overall fuel gas consumption of the process remains the same It is extremely important to define whether a credit for this fuel gas recovery system is allowed This is especially important if one production process recovers not only its own flare losses but also the losses to flare of other production processes on the site From the above considerations it should be clear that it is important to agree on the rules of how to deal with waste when setting up the framework to define the EIFEEI of a processunit One possibility is to define for a given process the reference practice on the amount of waste generated and to what extent it is recycled and to give an energy credit to those operators who are able to use the waste in a more efficient way than the reference case In any case it is essential that each industry defines clearly how to deal with wastes to allow a fair comparison between competing production processes

4 Primary energy conversion factor for electricity To be able to compare different forms of energy vectors it is necessary to define the concept of primary energy For electricity this is the quantity of energy required to produce one unit of electricity For instance current gas powered electricity stations based on combined cycle technology have an efficiency of approximately 55 to convert gas to electricity (defined as the amount of electricity out (in GJ)lower combustion value of gas going in) With CHP it is possible to reach 85 efficiency Different countries may use different conversion factors depending on the actual mix of plants used to produce electricity (eg hydropower combustion plants nuclear) Moreover this efficiency factor may increase over time as older plants are closed and more efficient plants are taken in operation Again it is important to clearly define which efficiency factor should be used Examples of defining the primary energy conversation factor bull when monitoring the energy efficiency improvement of a production process over time it

is important that in the definition of EIF and EEI the electricity conversion factor is kept constant If not it is not possible to separate the effect of an improvement in the energy efficiency of the process itself and the effect of the improvement of the energy efficiency of the electricity production in the country where the production process is located

bull however when reviewing the impact on the energy efficiency of a process when switching from one energy vector to electricity (eg changing from a steam turbine to an electric motor) it could make sense to use the actual electricity efficiency production factor of the country This allows the operator to look at what the best solution is for the combined total picture of the production process and the electricity production which may have another optimum than that of the production process alone

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5 Steam A definition which is often used for steam is the following (also see Section 43) Energetic value of steam = hs-hwnb Equation 28 Where bull hs enthalpy of steam bull hw enthalpy of boiler feed-water (after deaeration) bull nb thermal efficiency of boiler Often this thermal efficiency only takes into account the losses of heat in the stack of the boiler The deaerator is often not seen as part of the boiler (often this deaerator is common to many boilers and furnaces) Hence the following energy inputs are sometimes not taken into account for defining the energy value of steam bull energy required to pump boiler feed-water to operating pressure of the boiler bull heat added to boiler feed-water to bring it to the temperature of the deaerator bull steam sparged in the deaerator to remove oxygen from the boiler feed-water bull energy consumed by the air fan providing forced draft to the boiler

The difference in the energy required to produce the steam and the energetic value of the steam will then be counted at the site level rather than at the production process level At site level the steam will be allocated to the utilities plant (see Section 224) This is in principle not a problem The approach presented in Equation 22 and Equation 24 allows measurements to be made in the improvement of energy efficiency of a process itself and decoupling it from improvements in the energy efficiency of the steam generation process However again for a comparison between different plants making the same product one needs to make a comparison based on the same assumptions for the energetic value determination of steam

6 Load factor the reduction of the specific energy consumption (energy intensity factor EIF) with an increasing production rate is quite normal and is caused by two factors bull the production equipment will be operating for longer periods when the production rate is

high This means that the idling periods become shorter Some types of equipment run continuously even during non-production times This period will be reduced when the non-production time gets shorter (see Figure 214)

bull there is a base energy consumption that does not depend on the utilisation of production capacity This consumption is related to the use of lighting fans for ventilation office machines etc Neither is the heating of the premises dependant on the production but rather on the outdoor temperature as is shown in Figure 216 At higher production rates the consumption will be spread over more tonnes of products

This will be taken into account by the sectorsite-specific correction factor

7 Standards For some components and systems there are already energy efficiency standards (eg boilers motors) which are minimum requirements for appliances and systems

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233 Structural issues In addition to items dealt within Sections 231 and 232 related to internal issues to be decided when deciding on energy efficiency indicators there are several more structural issues which influence energy efficiency and should be considered and understood when deciding the system boundaries In this section there are some examples of issues companies may face and when decisions must be made on how these measures and changes influence the energy efficiency and how to update the indicators not to lose transparency However in all cases if structural changes are implemented also reference performance for energy indicators should be updated The origin and changes in energy efficiency are sometimes difficult to interpret The factors to influence energy efficiency can be active measures of company policy to improve energy efficiency by investments in processes or utilities or some measures over which the company does not have full control Effects by improvements of practices are in every case difficult to measure evaluate and maintain The decision of system boundaries and energy vectors (energy flows) should be made in a transparent way to follow the logic and decide what the real energy efficiency measures are and what the structural changes In some cases structural changes may improve energy efficiency and in some cases not this also depends on the system boundary When changes happen it should be easy to update the data Some examples follow and relate to the manufacturing and process industries In these cases system boundaries are drawn around the company If system boundaries are different eg extended to cover energy production plants in the country the recommendationoutcome would be different

1 Changes in the utilisation of production capacity Changes in production may have a significant impact on specific energy consumption Such changes are often caused by fluctuations on the market the competitiveness of the company and the buyersrsquo demand for the product In cases when the changes are due to market fluctuations and beyond the companyrsquos control they should not be quoted as energy efficiency measures If on the other hand the utilisation of capacity will be changed due to improved production planning meaning eg that the plant will be operated more intensely during fewer shifts this change should be regarded as an action to improve the energy efficiency (see Figure 213)

2 Changes in production technology Changes in production technology may be carried through eg as a result of technical development or because of new components or technical systems being available on the market Obsolete technical systems may need to be replaced and new control systems may need to be introduced to improve the production efficiency The introduction of such changes of production technology may also lead to improvements of energy efficiency Changes in production technology leading to more efficient energy use will be regarded as measures for energy efficiency improvements

3 Product development In some cases new units may need to be added to a production process to meet the market demand or to comply with new product specifications or with environmental requirements In these cases the EEI may deteriorate after the new unit has been put into operation because the new unit requires additional energy to work This does not mean that the site has suddenly neglected its management of energy

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46 Version April 2006 SSEIPPCBENE_Draft_1

An example of this situation was the adaptation of the refineries in years 2000 ndash 2005 to meet the new fuel specifications (low sulphur diesel and gasoline) set by the EURO IV regulation which has led to an increase of the refineries energy consumption Another example is from the pulp and paper industry which makes improvements of the fibers used in the process which leads to a reduction of energy use Somewhat later the quality of the finished product was also improved and this required an increased grinding After these two steps in technical development it turns out that the total energy use has increased

4 Lifecycle of a product A steel industry improves the strength of the delivered steel products The energy consumption in the new processes will increase The customers can reduce the plate thicknesses in their products by several tens of per cents The steel industry will experience an increase of the energy consumption per tonne product whereas the customers will benefit from the weight reductions in their final products

5 Changes in the production layout Changes in the production layout may eg mean that unprofitable production lines will be shut down media support systems will be exchanged similar lines of business will be merged etc Energy consumption will be changed as a consequence but this change will if regarded from a company standpoint be looked upon as a secondary effect Changes in the production layout can also be regarded to be measures for energy efficiency improvements

6 Close down of the manufacturing of a high energy product A company closes down the manufacturing of a product that requires high energy input Both the total and the specific energy consumption will be reduced This can be claimed to be a measure to improve the energy efficiency in spite of the fact that no other measures have been taken

7 Outsourcing By outsourcing the supply of media a company could eg shut off its compressed air centre The energy consumption could thus be reduced by buying compressed air from an external source The energy use will of course be increase by the supplier of compressed air The change must be clearly taken into account in the updating of energy efficiency indicators but it is not an energy efficiency measure

8 Laying out of process steps to other companies A company may for instance lay out the enamelling of plates to another company This is an example of an energy intensive process that is moved out of the first company but should not be looked upon as an action for energy efficiency improvements An automobile industry decides to increase their purchase of components instead of manufacturing such components themselves The result will be that the total and the specific energy consumption will decrease This must be taken into account in the updating of energy efficiency indicators

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9 Energy integration Internal power production without the additional supply of primary energy sources is an obvious means of improving energy efficiency If it is connected with an exchange of energy with surrounding enterprises system boundaries need to be defined and possible ambiguities settled When comparing electric energy with primary energy sources a conversion factor needs to be applied In the case of an additional supply of primary energy to a CHP plant in the company this may be regarded as an energy efficiency improvement

10 Use of oxygen in a combustion plant A company that increases the use of oxygen in a combustion plant will increase combustion efficiency and reduce fuel purchases Oxygen is not denoted as an energy source and the company may claim that they have improved their energy efficiency

11 Site or company integration Over the last few decades integration of industries has developed eg chemical sites with a high degree of integration have been formed This strategy offers considerable economic advantages This has resulted in complex sites with many operators present and with the utilities being generated either by one of these operators or even by a third party It may also result in complex energy flows between the different operators In general these big integrated complexes offer the highest potential for an efficient use of energy through integration However special caution is called for when defining the system boundary for energy efficiency for such complex sites In an isolated examination of a production process certain energy uses might seem inefficient even though they constitute a highly efficient approach within the integrated system of the site This may result in a situation where single operators are not always operating at their most optimum energy efficiency point but are compensated via commercial incentives in order to obtain the most competitive commercial environment for the integration of the site as a whole Some examples of benefits due to integration are bull the use of steam in a drying process seems to be less energy efficient than the direct use of

natural gas However when considering that this low pressure steam stems from a CHP process combined with highly efficient electricity generation the question of energy efficiency must be viewed in a different light

bull cogeneration plants located at the production site are not always owned by the production site but are often a joint venture with the local electricity generation company whereby the steam is owned by the site operator and the electricity is owned by the electricity company Care should therefore be taken in how these facilities are accounted for

bull when electricity is generated and consumed at the same site much lower transmission losses are expected and then the conclusion is evident that energy efficiency at integrated sites ndash which are quite common at chemical industry locations ndash is usually very high

bull within a highly integrated system residues from production processes are returned into the energy cycle Some examples are the return of waste heat steam into the steam network the use of hydrogen from the electrolysis process as a fuel substitute gas in the power plant process or as a chemical (eg raw material in hydrogen peroxide production) and the incineration of production residues in power plant boilers

All this makes it obvious that selecting appropriate system boundaries to define the energy efficiency of production processes is a sensitive matter

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48 Version April 2006 SSEIPPCBENE_Draft_1

24 Examples of application of energy efficiency 241 Mineral oil refineries The refineries already take seriously into account energy efficiency issues because energy costs represent more than 50 of global operating costs On a single refinery level energy efficiency can be followed by the energy intensity factor as defined in Section 222 In fact it is simpler to use the ratio between globally consumed energy on the site to the amount of treated crude which is equivalent to the EIF Following this ratio against time requires interpretation in order to clarify what comes from energy management and what comes from other factors However this ratio cannot be used for the purpose of comparing the energetic performance of different refineries as all refineries are different in complexities schemes processed crudes and production mixes All these parameters affect the energy needs of the refineries An attempt to catch this complexity is the Solomon Energy Benchmark for refineries For refineries Solomon associates have introduced the concept of the energy intensity index (EII) Solomon associates carry out a worldwide benchmark study of refineries every two years It covers all aspects such as capacity maintenance costs operational expenditure and also energy efficiency The energy efficiency is measured via the EII indicator which is defined as follows

Total actual refinery energy consumed EII = 100 x

Σ(Unit utilised capacity x Unit energy standard) + Sensible heat + Offsite energy

Equation 29 In Equation 29 bull the numerator is the total actual refinery energy consumption (expressed in lower heating

value) and equals the total consumption of fuelelectricity (both import and internal generation) but also takes into account any export of steam andor electricity Electricity from the external grid is converted to primary energy using a standard efficiency factor of 375

bull the denominator is the standard energy consumption according to Solomon (called guide energy) and consists of three main elements o the sum of the guide energies for each of the production units this guide energies are

calculated by multiplying the unit utilised capacity (normal throughput or feed rate) with a unit specific energy standard factor provided by Solomon for each unit For some production units this energy factor depends on feed quality (eg crude density)operation severity (catalytic reformers catalytic crackers etc)type of production facility etc These guide energies per unit are summed to give the total standard energy consumption for all of the refineries production facilities according to Solomon

o a sensible heat factor this factor accounts for the energy required to raise the plant input from ambient temperature to 1044 degC The basis for the plant input is all gross raw material input streams (and their respective densities) that are lsquoprocessedrsquo in process units Blend stocks are not taken into account

o an offsite energy factor this factor accounts for the energy consumed in utility distribution systems and operation of product blending tank farms (tank heating heating of rundown lines terminalling facilities) and environmental facilities The basis for the calculation is the raw material input to process units as well as to blending operations and a complexity factor of the refinery

The EII is dimensionless and in contrast to the definition of EEI presented in Section 222 decreases with increasing energy efficiency

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The EII attempts to compare the energy efficiencies of refineries having different complexities and different units Still this tool is considered by the refining industry as an imperfect tool for comparison purposes at best Some refineries that have a poor EII have few opportunities for improving energy efficiency whereas others with a good EII sometimes still have a large potential for improvement Moreover the EII does not give a good insight to the areasunits that need improvement The detailed breakdown of the site into main production units can be of more help in this respect to identify opportunities for improving energy efficiency

242 Ethylene cracker Ethylene crackers convert feedstock coming from the refinery into ethylene and propylene which form the main feedstock for the polymers industry Ethylene crackers are highly energy intensive Energy costs represent more than 50 of the operational costs of a unit Feedstocks (Fi) typically are naphtha LPG and gasoil coming from refineries The main products (P1) are ethylene and propylene (see Figure 22) Within the industry however it is the custom to add three other high value products to the main products for comparison purposes butadiene benzene and hydrogen Butadiene and benzene do not in fact come out as pure products in a cracker Butadiene is part of the C4 stream and benzene of the cracker gasoline stream They are usually extracted in dedicated extraction units which do not form part of the overall picture of the ethylene crackers Usually the ratio of these high value products to ethylene varies in a narrow window (between 17 and 23) and will depend on cracking conditions and feedstock qualitytype For plants where the economics are mostly driven by ethylene production a more meaningful energy indicator might be to divide energy use by ethylene production rather than by high value chemicals Energy vectors

bull steam a typical ethylene cracker would usually have several steam levels (a high pressure level of approx 100 barg a medium pressure level of approx 20 barg and low pressure level of approx 4 barg) Depending on the configuration the cracker will import steam at some levels and export at other levels

bull electricity most crackers are net electricity consumers Those equipped with cogeneration may be net exporters of electricity Within the industry the convention is to use a conversion factor of 375 to convert electricity to primary energy when comparing different plants

bull hot water most crackers produce relatively large amounts of hot water However in most cases the temperature of this hot water is too low for use by other plants but in some cases integration with other plants or outside consumers is possible In this case a credit should be given for export of these calories So an improvement of energy efficiency is determined by an lsquoexternalrsquo circumstance independent of the lsquointrinsicrsquo performance characteristics of the unit under examination that is the actual possibility of using an output stream for a duty that otherwise should be satisfied with additional primary energy As a consequence two units with the same lsquointrinsicrsquo performancersquo would be rated differently if only one of them can find an energy use for one of its output streams (heat integration)

bull fuel most crackers produce a liquid fuel (pyrolysis fuel oil) and gaseous fuel (a methane rich mixture) Most of the gaseous fuel is recycled to fire the ethylene furnaces Depending on the configuration and mode of operation the gaseous fuel produced may be self sufficient to fire all the furnaces and the rest of fuel gas is exported or there may still be a deficit so the import of an external fuel is required which is typically natural gas Only the fuel consumed internally by the ethylene cracker is taken into account in the energy balance All fuels exported are counted as products (this is logic as the fuel value was already present in the feedstock)

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50 Version April 2006 SSEIPPCBENE_Draft_1

bull cooling water all crackers use cooling water Sometimes cooling towers are part of the ethylene cracker however this cooling water comes from cooling towers which also supply cooling water to other production units In this case the energy related to the production of cooling water is often not reported when calculating the energy efficiency of the process

bull ethylene processes also use other utilities such as N2 and compressed air Often these utilities are produced centrally on the site or by a third party The energy related to these utilities is often not counted

243 VAM production Some of the components of the proposed Equation 24 Section 223 to calculate the energy intensity factor (EIF) may not be applicable for each process Therefore it has to be modified to the prevailing needs As an example a vinyl acetate monomer (VAM) plant is taken Several components of a VAM plant are not being measured or quantified (here marked with ()) whereas others can easily be named (here marked with ()) see Figure 211

VAM plant

Electrical power

Steam

Cooling water

Utilities

Catalyst inhibitor

Ethylene

Acetic acid

Oxygen

Recycled steam

Condensate

Cooling water return

Light ends

Heavy ends

Purge gas

Waste gas

Heat losses (isolation)

VAM

Water

CO2

Input Output

Figure 211 Inputs and outputs for a vinyl acetate monomer (VAM) plant

As stated in Section 223 heat losses via cooling water return and isolation should never be counted in the EIF or EEI Waste gas and purge gas should not be counted if it is incinerated without heat recovery For those terms it may however be useful to gain some insight into their order of magnitude to verify the economic potential needed to reduce these losses or waste streams In contrast more reflection is required on the other terms such as light and heavy ends or if waste andor purge gas are valorised in other processes In the proposed Equation 24 these streams were not included as it is assumed that the fuel content of these streams is already present in the feedstock However it is the responsibility of the operator to define how to account for these terms

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244 A rolling mill in a steel works The feeding to a rolling mill consists of approximately 2 decimetres thick flat steel plates that are to be rolled out to bands with a thickness of a few millimetres The rolling mill consists of furnaces rolling mill equipment cooling equipment and support systems including pumps fans hydraulics and lubricating systems lights a mechanical workshop staff space changing rooms etc A flow chart of a rolling mill is shown in Figure 212

Furnace

Furnace

Furnace

Rolling equipment

Boiler

Compressor

Cooling bed

Hundreds of pumps and fans at different locationsHundreds of pumps and fans at different locations

Slabs (materialsto be rolled)

Liquefiedpetroleum gas Electricity Cooling water Air

Exhaustgases

Air Scrap(reject

products)

Coolingwater Heat

lossesRolled

products

Figure 212 Flow chart of a rolling mill In this case several different primary energy sources are involved However the following discussion is restricted to the use of electric energy The number of electrically driven components or subsystems in a rolling mill can be estimated at more than one thousand The electric energy consumption can be registered easily with reliable electricity meters The steel production may either mean the weight of slabs entering the rolling mill or the weight of rolled and approved final products The difference corresponds to the weight of scraps that may fall at different stages in the rolling mill An analysis of data taken from an existing rolling mill during a period of 11 weeks was made and some of the results are shown in Figure 213 The energy consumption varied between around 120 and 80 kWh per tonne delivered products dependent on how many tonnes that were produced per week The average consumption was thus 100 kWhtonne and the variation plusmn 20 No energy saving measures were taken during this period

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52 Version April 2006 SSEIPPCBENE_Draft_1

Specific energy consumption in a rolling mill

200

600

1000

1400

010000 20000

kWh

tonn

e

Tonnesweek

Figure 213 Specific energy consumption in a rolling mill

The reduction of the specific energy consumption (energy intensity factor EIF) with an increasing production rate is quite normal and is caused by two factors bull the production equipment will be operating for longer periods when the production rate is

high This means that the idling periods become shorter Some types of equipment are running continuously even during non-production time This type of energy consumption will be reduced when the non-production time gets shorter

bull there is a base energy consumption that does not depend on the utilisation of production capacity This consumption is related to the use of lighting fans for ventilation office machines etc At higher production rates the consumption will be spread over more tonnes of products

The decrease in the specific energy consumption with increasing production rate is thus caused by fluctuations in market conditions which are beyond the companyrsquos control The question is if increasing the production and thereby reducing the specific energy consumption should be regarded as a measure for energy efficiency improvement

A program for improvement of the energy efficiency was later carried out at the rolling mill A number of measures were taken with the aim of decreasing the energy consumption and the results of these measures are illustrated in Figure 214

In this case a direct result of the energy saving measures could be observed The results appeared to be largely independent of the production rate As can be seen in Figure 214 it is possible to separate the results of energy saving efforts and results caused by other factors such as the utilisation of capacity

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SSEIPPCBENE_Draft_1 Version April 2006 53

Specific energy consumption in a rolling mill

10000 20000

Tonnesweek

kWh

tonn

e Energy efficiencyImprovements as aresult of an energysaving programme

Reduction of the energyconsumption as a resultof increased production

1400

1000

600

0

200

Figure 214 Specific energy consumption in a rolling mill

It is also obvious that interpretation difficulties will arise when comparing the specific energy consumption month by month or year by year The specific energy consumption may very well increase from one period to the next though a number of energy saving measures have been taken In this case the effect of such measures is not large enough to compensate for the increase in energy consumption due to low production rates

245 Heating of premises The heating of premises represents another case where the variation of the energy consumption to a great extent is beyond the userrsquos control The energy use is strongly dependent on the outdoor temperature as is shown in Figure 215

-20 0

Energy consumption forheating (MWhweek)

Weekly average outdoortemperature (degC)

Figure 215 Energy consumption depending on outdoor temperature

If measures like heat recovery from the outlet of ventilation air or improvement of house insulation are taken the graphline in Figure 215 will be moved downwards as seen in Figure 216 Estimates of the results of energy saving measures must thus be made with due consideration to outdoor temperature variations

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54 Version April 2006 SSEIPPCBENE_Draft_1

-20 0

Energy consumption forheating MWhweek

Reduction of energyconsumption due toenergy saving measures

Weekly average outdoortemperature (degC)

Figure 216 Energy consumption depending on outdoor temperature

There are apparent similarities between the diagrams in Figure 214 and Figure 216 The output value is the production of steel and the provision of a comfortable indoor temperature respectively In both cases the operator of the system has no control of the most important parameters customersrsquo purchasing of steel products and the outdoor temperature respectively

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SSEIPPCBENE_Draft_1 Version April 2006 55

3 ENERGY MANAGEMENT IN INDUSTRIAL INSTALLATIONS [6 Cefic 2005] [9 Bolder 2003] [89 European Commission 2004] [92 Motiva Oy 2005] [96 Honskus 2006] [108 Intelligent Energy - Europe 2005] This chapter deals with energy management in industrial installations in broad terms It explains why good structured management is important and which issues will be considered and taken into account in a good systemstructure It covers the elements which are crucial to manage energy issues efficiently both from an environmental and economic point of view It gives examples of good management structures approaches audits methodologies and other tools which could be implemented to improve energy efficiency Detailed descriptions of the tools is in the Section 32 dealing with methodologies Systematic and transparent ways to deal with energy issues are essential to reach the best environmental and economic results Energy is as any other valuable raw material resource required to run a business ndash not a mere overhead and part of business maintenance Energy has costs and environmental impacts and need to be managed well in order to increase the businessrsquo profitability and competitiveness and to mitigate the seriousness of these impacts All industrial companies can save energy by applying the same sound management principles and techniques they use elsewhere in the business for key resources such as raw material and labour as well as for environment and health and safety These management practices include full managerial accountability for energy use The management of energy consumption and costs eliminates waste and brings in ongoing cumulative savings

31 The structure and the content of energy management 311 General features and factors Energy management means structured attention to energy with the objective of continuously reducing energy consumption and improving efficiency in production and utilities and sustaining the achieved improvements Energy management is a useful instrument to improve the efficiency of energy systems both at company and site level It provides a structure and a basis for the determination of the current energy efficiency defining possibilities for improvement and ensuring continuous improvement All effective energy (and environmental) management standards programmes and guides contain the notion of continuous improvement meaning that energy management is a process not a project which eventually comes to an end Energy management does not only focus on technical possibilities (such as the installation of a special technique) but also takes into consideration the organisation the motivation of employees good practices and the co-operation of different departments and costs Very often energy management (energy issues) is an integral part of an environmental management system or other management system Energy management can be carried out at different levels which is expressed in following bull lsquolightrsquo energy management which could be described as lsquomanagement by intuitionrsquo bull energy conservation plans (ECP) based on the plan-do-check-act cycle (see Figure 31) of

continuous improvement bull energy management based on national standards (such as the Danish DS 2403 IR and SE)

or international guidelines (international standards or guidelines on energy management) However the company may not seek certification

bull energy management following a specific standard (and certified)

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56 Version April 2006 SSEIPPCBENE_Draft_1

Table 31 illustrates different levels of energy management in more detail It should be noticed that level 4 shows the best performance

Level Energy policy Organising Motivation Information systems

Marketing Investment

4 Energy policy action plans and regular reviews have the commitment of top management as part of an environmental strategy

Energy management fully integrated into managementstructure Clear delegation of responsibility for energy consumption

Formal and informal channels of communication regularly exploited by energy manager and energy staff at all levels

Comprehensive system sets targets monitors consumption identifies faults quantifies savings and provides budget tracking

Marketing the value of energy efficiency and the performance of energy management both within the organisation and outside

Positive discrimination in favour of lsquogreenrsquoschemes with detailed investment appraisal of all new-build and refurbishment opportunities

3 Formal energy policy but no active commitment from top management

Energy manager accountable to energy committee representing all users chaired by a member of the managing board

Energy committee used as main channel together with direct contact with major users

MampT reports for individual premises based on sub-metering but savings not reported effectively to users

Programme of staff awareness and regular publicity campaigns

Same payback criteria employed as for all other investment

2 Unadoptedenergy policy set by energy manager or departmental manager

Energy manager in post reporting to ad-hoc committee but line management and authority are unclear

Contact with major users through ad -hoc committee chaired by senior departmental manager

Monitoring and targeting reports based on supply meter data Energy unit has ad-hoc involvement in budget setting

Some ad -hoc staff awareness training

Investment using short term payback criteria only

1 An unwritten set of guidelines

Energy management is the part -time responsibility of someone with limited authority or influence

Informal contacts between engineer and a few users

Cost reporting based on invoice data Engineer compiles reports for internal use within technical department

Informal contacts used to promote energy efficiency

Only low cost measures taken

0 No explicit policy No energy management or any formal delegation of responsibility for energyconsumption

No contact with users

No information system No accounting for energy consumption

No promotion of energy efficiency

No investment in increasing energy efficiency in premises

MampT ndash monitoring and targeting

Table 31 Energy management matrix [107 Good Practice Guide 2004]

To illustrate the process thinking different models have been developed but one of the most commonly used is the plan-do-check-act (PDCA) 1 cycle (see Figure 31) The PDCA cycle is often known by company management from other contexts but energy This approach is also in line with the most commonly used management approaches and standards that are relevant to industry The PDCA cycle provides a framework for the continuous improvement of a process or system The cycle is designed as a dynamic model where the completion of one turn of the cycle flows into the beginning of the next

1 The PDCA Cycle was developed by Walter Shewhart the pioneering statistician who developed statistical process control in the Bell Laboratories in the US during the 1930s Therefore it is also often referred to as lsquothe Shewhart Cyclersquo It was taken up and promoted very effectively from the 1950s on by a famous quality management authority W Edwards Deming and is consequently known by many as lsquothe Deming Wheelrsquo

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SSEIPPCBENE_Draft_1 Version April 2006 57

ACT PLAN

CHECK DO

Figure 31 The plan-do-check-act-cycle (PDCA) [108 Intelligent Energy - Europe 2005]

Usually good energy management practices are based on a standard or a specification which is derived from something which is already known in particular the ISO 9001 management standard and the related environmental energy management standard ISO 14001 or EMAS An increasingly popular approach are also specific energy management standards which have been developed in three EU countries (DK SE and IE) and which (as a standard or as guidelines) are also planned by the CENCENELEC Successful implementation of energy management requires commitment by the company management conducting an energy audit analysis and target setting for example by making an energy conservation plan executing the actions needed to fulfil the targets setting up a monitoringmeasuring system motivating staff and having management reviews Finally it is necessary to implement the energy management system or a corresponding structure throughout the company on a permanent basis to ensure the continuous follow-up and improvement of energy efficiency Figure 32 illustrates the continuous improvement of an energy management system

Plan ndashgt Do ndashgt Check ndashgt Act approach

5 Management review (improve) (ACT)bull Management reportingbull Deviation reportsbull Review of Targets

4 Control and corrective actions (monitor) (CHECK)bull Control of deviations + corrective actionsbull Internal and external system auditbull Benchmarking

1 Energy policy (commitment)bull Legislation LTAbull Targets CO2 or energy efficiencybull BAT LCA LCC

2 PLANbull Targets and plan of action (ECP)bull EM system standards design

3 Implementation and operation (DO)bull Organisation and responsibilitiesbull Motivating awards trainingbull Energy monitoring and reportingbull Energy purchase reporting of LTA

Figure 32 Continuous improvement of an energy management system [92 Motiva Oy 2005]

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Energy management can be used in all companies because it provides a general approach and structure that offers flexibility to accommodate any specific branch of business With respect to corporate management this may be understood as being either the management of the holding company or of a business unit or of a site In the following sections a good environmental structure is dealt with on the basis of a management system It expresses what items a good energy management system includes A good energy management structure is based on PDCA cycle and contains corporate commitment planning and implementing of the structure to manage energy issues concrete measures tools and resources and monitoring both technical and management commitments

312 Commitment of the top management Top management commitment is the precondition for successful energy management If energy efficiency is high on the company agenda the necessary driving forces are created for the organisation Long range visions must be defined by top management In addition the corporate management needs to communicate the commitment of resources ndash people and financial - towards this vision This commitment enables the build-up of the necessary organisational structure and some benefits are bull make it clear to the staff that energy efficiency is to be taken seriously and will give it a

higher status bull organisationally this gives the company a platform where energy problems crosscutting

various departments can be solved bull investment decisions can be taken at the appropriate level bull prevents decline in attention to energy efficiency This commitment also needs to be visible and agreed at the highest levels in the company The vision needs to be clear and visible to all employees This includes reviews of progress by high level management of the company Reviews are part of the PDCA cycle Top management also needs to help initiate an organisational structure that can work towards the goal in an efficient productive manner A culture needs to be created and demonstrated that keeps the energy topic an everyday topic This means that enough resources are allocated and good practices are implemented and kept going If the company has included energy issues in its environmental management system (or other management system) the commitment of top management is always there and is included in company energy policy As much as possible existing structures should be used although new structures can also be considered If the company has a certified (ISO EMAS) environmental management system this will automatically include the continuous improvement approach

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The following bullets list success factors that motivate top management to carry out energy management bull participation in a well designed long-term agreement can be a good driver to work on

energy efficiency bull need to gain competitiveness by reducing production costs as the competition in the

European markets is increasing bull increasing energy prices are a driving force bull new investments in industry enhance the penetration of new technologies in the market

As a rule new technologies are more energy efficient bull in some countries new legislation and regulations are preconditions for improving energy

efficiency bull liberalised energy markets with new emerging energy services as well as public promotion

of cogeneration and renewable energies create new opportunities for effective energy management

313 Planning To implement the top management commitment which is included in companycorporation energy policy in practice in order to achieve results in energy efficiency the company has to start and continue to do proper planning A company needs to know where is it and what it is working towards A clear measurable and traceable common goal with a timeline and defined improvement steps is the first step on the road to implementation When deciding on a definition for the timeline and the improvement steps it is important that all relevant employees co-operate and work as a team The work starts by doing the initial energy audit and continues by deciding on targets measures and resources The following list of success factors for good energy management is identified bull case studies of good practices are helpful bull work in a methodical way do not implement measures in a random way

3131 Initial energy audit Essential for this first step is the inventory of actual status (absolute energy consumption flow of energies consumers energy accounting system) versus a reference (eg competition thermodynamic targets best available techniques trends over time) With the help of this information and the company vision the energy goals can be developed The tools and methodologies for inventories are dealt with in detail in Section 32 The target of the initial energy audit is to identify a companyrsquos energy consumptions and find measures to decrease the consumption Based on this information the company can prioritise and decide on efficiency goals In the audit relevant action areas for improvement and energy efficiency opportunities can be identified

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The initial energy audit contains the following items bull the identification of areas or activities with significant energy consumptions bull the collection and analysis of energy consumption data bull the identification of energy efficiency opportunities bull the identification of legal and other requirements bull the determination of baseline energy consumptions bull the identification of appropriate energy efficiency indicators bull the identification of practices related to energy issues bull identification with legal and other requirements to which the company subscribes and are

applicable to the energy aspects of its activities bull the documentation of the energy audit and its revisions Different types of audits are dealt with in Section 321

3132 Energy performance targets To set up performance targets and thestructure to implement those is a key issue in improving energy efficiency in a company The performance targets will be set for processes and other activities which have significant energy consumption and conservation potential and are related with legal or other rules and requirements It is important to understand the character of the individual business units to improve their energy efficiency On the other hand only an understanding of the interrelation of these units will guarantee the overall best results bull goal setting needs to take into account the other units on the site and even in the local

environment bull the definition of plans and distribution of resources needs to bear in mind the corporate

network conditions bull waste from one unit can be valorised as an energy carrier in another unit The energy performance targets are clearly defined and measurable They are documented and there is a time frame for their achievement Energy management achievements are monitored and benchmarked systematically The company also sets and revises its energy performance targets systematically according to bull the energy consumption significance bull the relevant legal aspects bull the companyrsquos current technological operational and financial capacity The energy performance targets are appropriate for benchmarking and consistent with the energy policy Appropriate indicators are very important for understanding the current situation and also for checking progress versus goals Thus all necessary data need to be collected stored and communicated constantly and consistently to calculate these indicators For finding measures to improve energy efficiency there are different tools like Pinch methodology audits etc These are dealt with in more detail in Section 32

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Continuous improvement is an essential element to drive energy efficiency Good energy management needs to follow the plan-do-check-act cycle which should be included in all management systems It guarantees that task and responsibilities are defined and progress is checked on a regular basis When operating within this cycle the actual performance is compared to planned performance Depending on results of this cycle further measures and tasks need to be defined or redefined

3133 Action plan The company will establish and maintain an action plan for achieving its energy performance targets and the realisation of the energy policy The action plan will include bull actions for the achievement of the energy targets bull the means and resources for each action bull designation of responsibility for each action bull determination of the time frame for each action bull deciding the indicators bull means to monitor indicators and targets The action plan is consistent with the companyrsquos energy policy and its current technical financial and operational capacity

314 Doing To achieve the goals it is necessary to have a proper action plan and a focused organisation Existing structures (like qualityenvironmental management) or it can be helpful to develop a new (independent) structure The tools that are used to drive energy efficiency can be energy specific like Pinch methodology energy audits and studies or come from general management toolsets which are either externally or internally developed The following list of success factors for good energy management is identified bull guide the company step-by-step through the implementation of energy management is

useful Energy advisors and other helpdesks are instrumental in this process Practical action-specific programmes are better than generic support and guidance

bull give the company access to tools that are easy to use for example o checklist for the level of energy management o tools for the implementation of energy management o tools for dailymonthlyyearly energy monitoring o reporting modules (eg for the competent authorities)

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3141 Structures and responsibilities The structures will allow for implementation and control of all aspects of the action plan like technical measures training of employees improvement of internal procedures communication and tracking The company will define and document roles and responsibilities of the staff and then communicate them in order to facilitate effective energy management Furthermore top management will provide resources essential to the implementation and control of the energy management systemstructure eg resources include human resources specialised skills technology and financial resources It will be beneficial to appoint an Energy Manager who irrespective of other responsibilities will have defined roles responsibilities and authority for bull the continuous improvement of the companyrsquos energy performance bull the implementation of the energy management system bull the monitoring benchmarking and reporting of the energy performance bull the staff involvement in the effort for energy performance improvement The company should assign responsibilities according to function level education experience personality and capability in order to achieve efficient implementation of the energy management system

3142 Awareness raising and capacity building The best energy efficiency cannot be achieved only by technological measures but also good practices and staff involvement are needed Benefits of investments may even be destroyed if human resources are not included and motivated It is crucial that staff are trained The company will communicate energy policy to all the personnel in order to inform and encourage personnel to contribute to energy performance improvement The company will inform its personnel about the following energy related issues bull the importance of energy efficiency to the company bull the companyrsquos efforts towards energy efficiency bull the consequences of their work activities in energy consumption bull their roles and responsibilities in the effort towards energy efficiency The company will identify the key personnel whose work significantly affects energy performance and specific training should be organised for these people in order for them to be efficient in energy management Appropriate training activities should be planned and carried out

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3143 Communication and motivation Communication and motivation are crucial tools so that modern companies can implement all kinds of issues Communication is a key element because it provides feedback to all partners about their performance Communication is used positively to provide recognition of achievers Communication includes bull inside an individual company all staff should be involved bull involving several companies from the same sector in a working group (energy networking)

to exchange experiences has proven useful The companies should all be at the same level of energy management implementation Networking is especially useful for solving typical difficulties such as defining an energy efficiency index or setting up an energy monitoring system Networking may also introduce an element of competition in energy efficiency and provide a platform for negotiation with potential energy efficient equipment or service suppliers

bull positive effects should be made clearly visible Awards for best practices are a possibility to implement this

Well structured communication secures the flow of information of goalscommitments as well as the achieved results The company will implement practices that ensure efficient two-way internal communication concerning the effort towards energy efficiency The company will also inform its staff about energy efficiency and systematically support encourage and motivate them to contribute to energy efficiency by conserving energy preventing unnecessary consumption working efficiently and making recommendations and observations Communication is also used to encourage the exchange of information with other companies - to swap best practice ideas and to pass success stories from one company to another etc The possible means of communication are a system of specific energy consumption numbers (daily weekly monthly yearly) over time or in correlation with important parameters (like production rate weather conditions) combined with success stories in periodically published reports Graphics are an excellent way to provide information

315 Checking The company cannot demonstrate its energy efficiency and improve its energy performance if it is not monitoring and measuring its energy flows and other important indicators This enables feedback to the management on the effectiveness of energy efficiency measures Take care that those responsible for energy efficiency have the ability to control it This means that good monitoring (lsquoif you canrsquot measure it you canrsquot manage itrsquo) and reporting are essential

3151 Monitoring and measurement Monitoring is an important element of the PDCA cycle and a prerequisite for demonstration of efficient energy use and benchmarking Monitoring is planned together with energy efficiency indicators

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A company will systematically measure and monitor its energy flows and other relevant factors which have been identified as crucial to follow Tools for monitoring are dealt with in Section 32 Appropriate energy indicators (see Section 22) are periodically calculated registered analysed and reported A company will evaluate its energy performance according to its energy targets Actions and practices will be amended for the achievement of energy targets whenever necessary A company will have practices to detect and investigate non-conformances that significantly affect its energy efficiency and will respond to them in order to minimise their negative impacts Monitoring will be dealt with in more detail in Section 322 Information will be collected via an energy information system which will also analyse and report the results

3152 Records The company will keep records of its energy performance that are tailored to their energy management system requirements Records should be legible identifiable accessible and traceable to the relevant process activity or person

3153 Periodic energy audits In addition to initial energy audits the company will periodically perform different energy audits in order to bull determine its current energy performance bull check the systemrsquos implementation and maintenance bull compare results with system targets bull provide benchmarking information bull investigate problems and identify causes and weaknesses bull inform the management of the company bull find new measures to improve energy efficiency Energy audits are dealt with in Section 321

316 Acting The companyrsquos top management will periodically review the energy management system and the results to ensure its continuing suitability adequacy and effectiveness and to evaluate its performance via benchmarking The review process will ensure that the necessary information is collected to allow management perform this evaluation The management review will address the possible need for changes to energy management policy objectives and practices in the light of energy audits results changing conditions and the commitment to continual improvement of the companyrsquos energy performance

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317 Examples of energy management systems and its implementation No information provided We expect to include here real examples of application of energy management systems in different industrial sectors and companies This also includes bull all steps in the management cycle bull data of energy efficiency improvements bull economic data

32 Methodologies and tools for energy use optimisation and energy efficiency

This section describes the tools which have been developed to support energy management The following list shows various tools which have been identified and which are described in more detail in the succeeding sections bull energy audits bull energy monitoring bull energy models bull pinch methodology bull benchmarking bull e-learning bull checklists bull good housekeeping The different tools are described in a relevant and suitable way in every case

321 Energy audits [92 Motiva Oy 2005] [40 Meireles 2005] [31 Despretz ] [7 Lytras 2005] The term lsquoenergy auditrsquo is in principle well known and commonly used What is actually meant by the term in individual cases can in practise include an extremely wide range of different applications The variety within the family of energy audits should be understood as should the importance of also defining the the scope content and depth of the audit in more detail Audits are crucial tools in energy management Different types of audits (technical audit best practice audits management audits) may be used in different phases and four different purposes during the implementation of energy management systems An energy audit is a systematic analysis of energy usage which identifies the main areas operations and types of energy used in a unitprocesssite It may also identify the cost effective energy saving opportunities and report the findings

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3211 Audit models In most cases energy audit is one module among other energy efficiency activities Figure 33 shows the basic energy audit models

THE SCANNINGMODELS

THE ANALYSINGMODELS

The walk throughenergy audit

The preliminaryenergy audit

The selectiveenergy audit

The targetedenergy audit

The comprehensiveenergy audit

MAG

NIT

UD

E

AC

CU

RA

CY

VERTICAL HO

RIZ

ON

TAL

The systemSpecific Energy

Audit

Figure 33 Basic energy auditing models [92 Motiva Oy 2005]

An audit model is usually a standardised commonly known and commonly followed procedure with written guidelines The requirements are usually defined in the guidelinesstandards given by company itself or by the standardisation body An energy audit may cover a site or a building in various ways ndash the scope of audits may be different At the lsquonarrowestrsquo an energy audit covers typically only one specific system (or a process) and at the lsquowidestrsquo an energy audit covers everything inside the site fence Between these lsquonarrow and wide endsrsquo there are energy audits that deliberately ignore some areas or issues In most audits related to the implementation of standards there are clear requirements as to what audits should include Energy audits are used for different purposes either for pointing out the areas where savings can be made or for describing in detail the actual saving measures so that they can be easily implemented These properties of energy audit models are illustrated in Figure 34

NARROW WIDE

ROUGH COMB FINE COMB

TO POINT OUT TO PROPOSE

THE SCOPE

THE THOROUGHNESS

THE AIM

Every systemall sites

Detailed potentialassessment

Specific energysaving measures

Specific systemarea

General potentialassessment

General energysaving areas

Figure 34 The properties of energy audit models [7 Lytras 2005]

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SSEIPPCBENE_Draft_1 Version April 2006 67

This section presents the different energy audit models divided into two main classes according to their aim to the scanning energy audit models and to the analysing energy audit models (see Sections 32111 and 32112) Within these two classes the different models have been specified according to their scope and thoroughness The basic energy audit models are not used very often as such and therefore the models in actual use are different types basic model applications The applications have different features depending on an interface to the connected activities

32111 The scanning models The main aim of the scanning energy audit model is to point out areas where energy saving possibilities exist (or may exist) and also to point out the most obvious saving measures Scanning audits do not go deeply into the profitability of the areas pointed out or into the details of the suggested measures Before any action can be taken the areas pointed out need to be analysed further A scanning audit model is a good choice if large audit volumes need to be achieved in a short time These types of audits are usually quite cheap and quick to carry out From the companyrsquos point of view a scanning audit may not bring the expected results because it does not necessarily bring actual saving measures ready for implementation but usually suggests further analysis of key areas

Walk-through energy audit A walk-through energy audit is suitable for small and medium sized industrial sites if the production processes are not very complicated in the sense of primary and secondary energy flows A walk-through energy audit gives an overview of the energy use of the site points out the most obvious savings and also points out the needs for the next steps (supplementary lsquosecond-phasersquo audits) The walk-through energy audit has been used by ESCOs in the scanning phase of third party financing projects

Preliminary energy audit The scanning energy audit model for large sites is called the preliminary energy audit Audits of this type are typically used in the process industry Although the main aim of the preliminary energy audit is in line with the walk-through energy audit the size and type of the site requires a different approach Most of the work in the preliminary energy audit is in building up a reliable breakdown of the present total energy consumption and defining the areas of significant energy consumption and usually also of the probable energy saving measures The reporting also points out the areas where supplementary lsquosecond-phasersquo audits are needed and how they should be targeted (see Section 3131) The preliminary energy audit normally needs to be carried out by a team of experts Expertise is needed both on the auditing procedure itself as well as on the production process The preliminary energy audit always requires committed participation from the technical personnel of the site

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32112 The analysing models The analysing energy audit models produce detailed specifications for energy saving measures providing the audited client with enough information for decision-making Audits of this type are more expensive require more work and a longer time schedule but bring concrete suggestions on how to save energy From the companyrsquos point of view the saving potential can be seen and no additional surveys are needed The analysing models can be divided into two main types bull selective energy audits where the auditor is allowed to choose the main areas of interest bull targeted energy audits where the company has defined the main areas of interest

Selective energy audit The selective energy audit looks mainly for major savings and does not pay attention to minor saving measures This audit model is very cost effective when used by experienced auditors but may in the worst case be real lsquocream skimmingrsquo There is always the risk that when a few significant saving measures are found the rest will be ignored

Targeted energy audit The content of work in the targeted energy audit is specified by detailed guidelines from the company and this means that most of the systems to be covered by the targeted energy audit are known in advance The guidelines set by the Company may deliberately exclude some areas The reason for excluding certain areas may be that they are known to be normally non-cost relevant The targeted energy audit usually produces a consumption breakdown and includes detailed calculations on energy savings and investments If the guidelines are adequate the audit produces a standard report From the companyrsquos point of view the targeted energy audit is always a risk if quality control is neglected if there is no control on the auditorsrsquo work they may be tempted to slowly move towards the selective energy audit because this model always includes less work System specific energy auditAn example of the targeted energy audit at the simplest and smallest is the system specific energy audit This type of audit has a tightly limited target (one system device or process) but the thoroughness of the work is usually very high The benefit of this audit model is that it is possible to have the best expertise on the work normally better than what an average auditor can provide The system specific energy audit produces a detailed description of the system and points out all profitable saving measures with alternative options concerning the specific system One good option is to combine this kind of audit as a sub-model with some more comprehensive audit models System specific energy audits give high saving potentials compared to the energy use of the system The problem is that when looking at only one part of the site the lsquobigger picturersquo is missing and a risk of partial optimisation exists For example when only studying only energy efficiency of compressed air or cooling systems heat recovery opportunities cannot be evaluated because there is no knowledge as to where heat could be used in the most efficient way Energy systems are usually interrelated and seldom independent

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SSEIPPCBENE_Draft_1 Version April 2006 69

Comprenhensive energy audit A comprehensive energy audit is a targeted energy audit at the lsquowidestrsquo end of the scale it covers all energy usage of the site including mechanical and electrical systems process supply systems all energy using processes etc Some minor systems may be excluded but they should not really be relevant in proportion to the total energy consumption The clear difference to the targeted energy audit is that the targeted energy audit deliberately ignores some areas that are known and specified in advance and the comprehensive energy audit covers everything The starting point in this type of audit is always an analysis on the detailed breakdown of the total consumption The comprehensive energy audit comments on all systems using energy specified at the beginning - regardless if savings are found or not it points out all profitable saving measures and includes detailed calculations on energy savings and investment costs This model also creates a basis for a very standard and detailed reporting which brings some advantages to the company especially in quality control and monitoring

32113 The technical coverage of energy audit models Depending on the goals of the energy audit programme or activity the audit models can be defined to cover different aspects of the site If the main target of the programme is to achieve energy savings then all energy use should be analysed However if the main aim is to promote the use of renewable energy sources the viewpoint is slightly different The technical content of an audit model can be illustrated by a lsquobox-modelrsquo Figure 35 Figure 36 and Figure 37 give an idea of the different approaches

ENERGY PRODUCTION ON SITEENERGY PRODUCTION ON SITEBUILDING ENVELOPEBUILDING ENVELOPE

BUILDING SERVICE SYSTEMSBUILDING SERVICE SYSTEMS

PROCESS SUPPLY

PRODUCTIONPROCESSHEATING AND FUELS

WATER

ELECTRICITY

RENEWABLES

Figure 35 Coverage of an industrial site energy audit [7 Lytras 2005]

The comprehensive energy audit for an industrial site covers all energy use of process process supply systems building service systems and heat production

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ENERGY PRODUCTION ON SITEENERGY PRODUCTION ON SITEBUILDING ENVELOPEBUILDING ENVELOPE

BUILDING SERVICE SYSTEMSBUILDING SERVICE SYSTEMS

PROCESS SUPPLY

PRODUCTIONPROCESSHEATING AND FUELS

WATER

ELECTRICITY

RENEWABLES

Figure 36 Coverage of a district heating connected to a residential building energy audit [7 Lytras 2005]

In a district heating connected to a residential building the energy audit covers the total picture of the building service systems Electricity use by the residents is ignored

ENERGY PRODUCTION ON SITEENERGY PRODUCTION ON SITEBUILDING ENVELOPEBUILDING ENVELOPE

BUILDING SERVICE SYSTEMSBUILDING SERVICE SYSTEMS

PROCESS SUPPLY

PRODUCTIONPROCESSHEATING AND FUELS

WATER

ELECTRICITY

RENEWABLES

Figure 37 Coverage of a CHP plant energy audit [7 Lytras 2005]

In a CHP power plant energy audit the energy production process is analysed and the possibilities for using renewable are investigated

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SSEIPPCBENE_Draft_1 Version April 2006 71

3212 Audit tools Lot of tools have been developed to lsquostandardisersquo contents and approaches of audits Usually companies have tailor-made tools like checklists to use in auditing procedures The following paragraphs will describe some of the tools bull informationdocumentation on technical topics (eg ECOs1 branch specific) - this is

an information support document which is often based on case studies and intended to help in marketing the audits in view of successful examples The main target is the benefactor of the audit This document focuses on one particular technique andor a specific subsector (in the industry) and the information given is summarised mainly on results and interviews Depending on the accuracy of the information these tools can also be considered andor used as promotion support elements

bull audit guide or audit handbook energy management handbook ndash this is a core component of an energy audit scheme which is the basis of training sessions and is targeted essentially to auditors It explains and describes how an audit is to be made how the calculations are to be conducted the types and contents of the most frequently proposed energy conservation options (ECOs) Although auditors are supposed to have a fair background in thermodynamics (and also electricity) these handbooks frequently entail a section of reminders of these energy related topics

bull energy checks checklists or walk-through guides - associated with energy audit models of the scanning type these supporting documents are developed in order to facilitate the work of the auditor assuring at the same time both quality and rapidity of the survey They are primarily intended for energy auditors but can also be used as self auditing tools for those energy managers in industrial premises who intend to start an energy management process by themselves before requiring external assistance

bull calculation methods and software - another core component of energy audit schemes are calculation methods and software which are associated to energy audit models of the analysing type Their primary objective is to help the auditor in the quantitative assessment of energy saving potentials and evaluation of investment costs and paybacks The use (by an auditor) of a recommended or certified calculation tool (provided it is used correctly) is a certainty for quality results quality for the audited client

bull data collection form(s) - generally associated to the calculation tool for which they constitute the input data this type of support document helps the auditor in collecting all the necessary information for the survey It will be part of the final report and will also contribute to facilitating the follow-up of the site energy features and the interpretation of the audit results and recommendations

bull report templates - as for data collection forms report templates are also frequently associated with the calculation tool of which the output results must be integrated in the report The report is the deliverable of the audit proposing a template helps all the participants to make the most profitable use of the audit service and produce good quality audit reports

bull checklist for quality control of audit reports ndash this checklist is a document which can be used at both company level and at auditor level (self-check) it is a complement or an alternative to report templates and a practical translation of energy audit models what is specified in the energy audit model as expected results should be in the report and the checklist is an easy way to verify that the work has thus been done according to the specifications

bull building ratings target values or benchmarking - key figures can be used either as marketing information to spark off the need for energy audits they are also used by the auditors as technical data to justify their recommendations in the case of simplified audits and can even contribute to detailed audits in checking calculations or replacing data difficult to meter or evaluate either way

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bull databases on energy conservation options (ECOs) - one difficult part of the audit is having detailed information on costs and consequences of energy saving recommendations A database of ECOs encompassing this information will save a lot of time and money for the auditorcompany and thus help lower the cost of the audits with a maintained quality Keeping the data up-to-date requires quite a lot of work

Many of these tools may overlap and it is the responsibility of the company to determine what is necessary to use The above-mentioned tools are in general not specific of a target sector or an energy audit model but their usefulness frequently corresponds to one or several phases of the audit survey

322 Energy monitoring [55 Best practice programme 1998] [56 Best practice programme 1996] [98 Sitny 2006] Energy monitoring is the predominant activity within energy management to use and interpret energy use information The objective of monitoring is to get reliable and traceable information on the issues which influence energy efficiency (eg energy flows press-levels) Energy monitoring is a practical tool used for demonstrating that energy efficiency objectives set in energy programme for a whole company are implemented and achieved To achieve those objectives some sub-objectives or targets are set in the monitoring system Also eg material flows can be incorporated in the monitoring system Monitoring is at the heart of any strategic approach to energy management If there is no special energy management system the monitoring must be linked to other management systems Monitoring enforces the principle that energy should be viewed as a production cost rather than an overhead A monitoring system provides management information on the use of energy and other resources This information is collected by several relevant measuring points in the process and utilities and then analysed in cost accounting centres (EACs) and further at department and site level Energyenvironmental account centres are the units at the site where energy usage can be related to a production variable such as throughput The structure of the monitoring system is illustrated in Figure 38

Meters

SITELevel 1

DepartmentLevel 2

DepartmentLevel 2

Account centreLevel 3

Account centreLevel 3

Account centreLevel 3

Account centreLevel 3

Figure 38 Structure of a monitoring system [98 Sitny 2006]

This monitoring process is continued on a regular basis and the information is collected in the form of reports on performance against targets Regular reviews of these reports improve awareness of resource consumption and highlight areas where efficiency can be improved as shown in Figure 39

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SSEIPPCBENE_Draft_1 Version April 2006 73

Measure energy consumptionand production

Review performanceand action plan

Implement energysaving measure

Develop targets

Produce reports to monitor energy use

against output

Figure 39 Monitoring process [98 Sitny 2006]

The principle of this monitoring is a universal methodology and so not limited to a specific sector Therefore the approach can be used for virtually all sectors eg for the food and drink industry metal industry chemical industry buildings and transport but the degree of complexity varies An operating monitoring system consists of six major steps These are bull metering metering energy usage through a system of sub-meters to identifiable areas or

individual pieces of plants eg named as energy account centres (EACs) The most common intervals are weekly daily or shifts Monthly invoices from utilities are generally not sufficient

bull targeting determining target levels for each of the EACs by relating the energy usage to a measure of activity eg the output of the production line in a factory or outside temperature

bull analysis establishing a regular reporting system in most cases weekly that gives a performance measure for each EAC and identifies variances in terms of financial gain or loss A variance prompts an analysis maybe including further investigation and then an action

bull accountability to make people responsible is a powerful way of ensuring their commitment bull energy teams setting up energy teams that meet regularly to discuss ways of improving

performance and to carry out the actions identified In addition a regular feedback mechanism on performance to all levels of the company creates greater awareness and the motivation to improve

bull action taking action to reduce waste of energy The monitoring system reveals energy losses and all those involved must make decisions to implement the measures to improve the situation Monitoring helps to identify problems and then the correct action can be taken Action is essential for achieving savings

323 Energy models [11 Franco 2005] A very basic issue for improving energy efficiency is to know the starting point In many cases there are not proper measurements and so the information even from the use of energy is very vague To improve the situation a measurement system must be set up Usually an energy audit is needed and based on that information will be gathered

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74 Version April 2006 SSEIPPCBENE_Draft_1

Energy models are useful tools to carry out complete and in-depth energy diagnoses in whatever context (industrial service buildings) The aim of an energy diagnosis is to identify and select a number of actions that once implemented reduce the cost of the supplied energy It is possible to reach such an aim by bull rationalising important energy streams bull identifying ad-hoc energy saving technologies bull recovering waste energy streams bull optimising energy supplying contracts Each of the above goals has to be focused on two aspects one technical and the other economic however only the technical aspect is described here The technical aspect both under a theoretical andor experimental point of view concerns knowledge of productive plants and services Such knowledge has to be formalised so that it can be easily managed The first tool to fix the technical knowledge about plants is an energy model The model both electric and thermal summarises all the energy consumptions in the studied context in the form of a data sheet A reliable energy model is the primary tool one can face the energy question with It should be complete but not redundant easy to write out handy to consult useful for the heads of different departments such as energy management maintenance purchasing and accounts An energy model is based upon data collected lsquoin the fieldrsquo or after hypothesis and evaluations It is preferable if the data are collected and classified as follows bull department or production line bull utilities (compressed air pumping vacuum external lighting etc)

3231 Example 1 Electric energy models For the electric model at least the following data for each working device needing electricity such as motors and drives pumps compressors electric furnaces etc are gathered bull rated power bull rated efficiency bull load factor bull working hours per year Whereas power and efficiency are easy to detect as they are normally labelled on the device itself the load factor and the hours per year is estimated When the load factor is estimated to be greater than 50 then the load factor itself is approximately equal to

P(eff) LF= P(rated) x ŋ Equation 31

where bull LF is the load factor bull P(eff) is the estimated average electric power effectively absorbed by the device during its

working hours (kW) bull P(rated) is the rated power (kW) bull Ŋ is the rated efficiency of the device (at full load)

Chapter 3

SSEIPPCBENE_Draft_1 Version April 2006 75

If necessary Peff can easily be measured by some electric power meters It must be pointed out that the efficiency and the power factor of a device depend on the load factor according to Figure 310 drawn in this case for a generic motor

Efficiency

Power factor

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100Load factor ()

Figure 310 Power factor of a device depending on the load factor [11 Franco 2005]

If the single case must be handled attentively eg because of the dimensions of the machinery or its importance in the process then the auditor must calculate the real efficiency by means of a specific diagram for a specific device Once the real efficiency has been determined then this correct value should be used in Equation 31 The contect of a simple electric model is illustrated in Table 32

A B C D E F G

DEPARTMENTS DEVICES n Rated power

kW

Rated efficiency

Working hours per

year

Load factor

Energy consumed

kWh

Department 1 Device 1 10 55 092 500 1 298913

Device 2 20 4 085 4000 08 301176

Device 3 15 10 09 4000 09 600000

Total Dept1 780 1200089 175

Department 2 Device 1 1 500 085 3500 05 1029411

Device 2 20 15 09 4000 1 1333333

Device 3 5 75 08 4500 09 189844

Device 4 10 2 075 1500 08 32000

Device 5 3 150 092 3000 095 1394022

Total Dept 2 1307 3978611 581

Department Device hellip hellip hellip hellip hellip hellip

TOTALS 3250 5425000 1000

Table 32 A simple electric model lsquonrsquo in column lsquoArsquo represents the number of identical devices (under both a technical and an operating point of view) present in that department

Chapter 3

76 Version April 2006 SSEIPPCBENE_Draft_1

The lsquoenergy consumedrsquo in column lsquoFrsquo is given by multiplying the number of devices x rated power x working hours x load factor and dividing by rated efficiency

A x B x D x EF= C Equation 32

By adding all energies consumed in each department the total energy consumed by the entire plant can be calculated If the context studied is not so broad or complex this kind of model could be adequate to detect the areas where energy saving possibilities are most likely to be found It is sufficient to direct attention to the distribution of electricity consumptions for each department shown in column lsquoGrsquo It is very likely that a series of actions to improve energy efficiency will be found in those departments where consumption of energy is the highest while departments whose consumption is low can be neglected or taken into account later When the context deserves it (because the cycle of production is extremely complex or when energy data have never been collected before) it would also be useful to collect following data to identify energy saving actions eg bull for motors and drives

o kind of machinery driven by the motor (compressor fan pump etc) o identification code o manufacturer and model name o type of motor o installation year or residual life o number of rewinds carried out so far o type of speed control if existing o type of mechanical transmission o possibility to shift the operation to different times (to exploit more favourable electricity

tariffs at specific times or on specific days) bull for lighting apparatus

o type of lighting body o number of lamps in a body o number of lighting bodies o type of lamps o rated power of the lamp o efficiency of the lamp o kind of ballast (iron copper or high frequency)

Validation Since a good energy model is a strategic tool to carry out an energy audit it is mandatory to validate it before use The first step to validate an energy model is to compare the total amount of energy consumed as derived from calculations with the amount consumed as shown in the invoices for energy supplies If the context is very broad or complex it would be useful to compare partial amounts of energy consumed in each department with the amounts locally recorded by some automatic accounting device

Chapter 3

SSEIPPCBENE_Draft_1 Version April 2006 77

If there is not a good correspondence between the two amounts of energy (coming from the energy model and from invoices) this means that the hypothesis assumed at the beginning to draw up the energy model must be modified In particular the load factors and the working hours for the different devices must be determined with greater accuracy Another cause for non correspondence is the failure to take into account all devices really working in the plant

3232 Example 2 Thermal energy models The drawing up of a thermal energy model is more complex than an electric model To have an exact and reliable picture of the thermal consumption two kinds of models are compiled first level models and second level models To compile the first level energy model it is necessary to take a census of all users of any kind of fuel For any consumer of fuel (eg boilers furnaces etc) the following data should be recorded bull kind of fuel supplied quantity in a year bull kind of thermal carrier entering the boiler (eg pressurised water) flowrate temperature

pressure bull condensate percentage of recovery temperature pressure bull boiler body manufacturer model installation year thermal power rated efficiency

exchange surface area number of working hours in a year body temperature average load factor

bull burner manufacturer model installation year thermal power bull exhaust flowrate temperature average carbon dioxide content bull kind of thermal carrier leaving the boiler (eg steam) temperature pressure Though all previous data should be collected in the first level thermal model (lsquogeneratorsrsquo sidersquo) only a few of them must be taken into account as in the drawing of an electric model (see Table 33)

A B C D E F G

PROCESS Device n Rated power kWth

Rated efficiency

Working hours per

year

Load factor

Energy consumed Nm3 CH4

Big kilns 4 800 085 7700 08 2417000 Phase 1 (eg burning) Small

kilns 5 600 085 7700 08 2266000

Total Phase 1 6200 4683000 765

Hot water boiler 2 2500 092 1000 05 283200

Steam boiler 2 1000 092 7000 05 793200

Phase 2 (eg heat production) Hot water

boiler 2 1000 092 1600 05 181200

Total Phase 2 9000 1257600 205

Spray drier 1 400 07 200 1 11900 hellip Hot air generator 1 400 085 1600 05 39200

Small heaters 37 30 08 1600 05 115700

Phase 3 (eg Services)

Big heaters 2 60 08 1600 05 12500 30 Total Phase 3 2030 179300

TOTALS 3250 6119900 1000

Table 33 Data ina thermal energy model (generators side)

Chapter 3

78 Version April 2006 SSEIPPCBENE_Draft_1

In this case to make the comparison easier the energy consumed has been estimated as Nm3 of natural gas The amounts of natural gas consumed are given in this case by

A x B x D x E x 3600F= C x 34500 Equation 33

Where 1 3600 conversion factor from kWh to kJ 2 34500 is the net heating value for natural gas (kJNm3) The first level thermal model (lsquogeneratorsrsquo sidersquo) must be checked to see if the total amount of energy demand is equal to the total energy reported in the invoices for natural gas supply If so the model is reliable and useful to indicate the best areas in which to implement energy saving actions When assessing the thermal use of energy second level models (lsquousersrsquo sidersquo) are also required to be built To draw up such data sheets it is necessary to take a census of all machineries needing thermal energy in any form (hot water steam hot air etc) except fuel (taken into account in the first level model) For every item of machinery the following data should be collected bull kind of thermal carrier needed bull hoursyear of thermal demand bull load factor at which thermal energy is used bull rated thermal power

Such data can be arranged in Table 34 as follows

A B C D E F G

DEPARTMENTS DEVICES n Thermal carrier

Thermal power kWth

Working hours

per year

Load factor

Energy request

Nm3 CH4

Department 1 Device 1 2 steam 500 1000 1 104200

Device 2 1 steam 125 500 08 5200

Device 3 5 hot water 75 5000 08 156400 Total Dept 1 265800 218

Department 2 Device 1 1 steam 75 2500 05 9800

Device 2 20 hot air 10 3000 1 62500

Device 3 5 steam 50 2500 08 52100

Device 4 10 hot water 5 1500 08 6300

Device 5 3 steam 25 3000 09 21100 Total Dept 2 151800 125

Department Device

TOTALS 1215700 1000

Table 34 Data in a thermal energy model (users side)

Chapter 3

SSEIPPCBENE_Draft_1 Version April 2006 79

The second level model (lsquousersrsquo sidersquo) is useful to verify the match between the heat supplied by the utilities (boilers heat generators etchellip) and the heat requested by the users In this case the amounts in column F are given by

A x C x D x E x 3600F= 34500 Equation 34

In the previous example the calculation was as follows 1257600 + 179300 = 1436900 Nm3 of natural gas supplied In the second level model the calculation shows 1215700 Nm3 of natural gas demand The 15 difference is due to the efficiencies at following steps heat generation distribution piping and regulation and final use If this difference is acceptable then the two models can be considered as lsquocertifiedrsquo in the opposite case some correction (normally to the number of working hours or the load factors) is needed to reach convergence If the difference between the two amounts is big this is due to a high level of losses in the production-distribution-use for different carriers (eg steam hot water etc) In this case different actions aiming to improve the energy efficiencies for example in the field of insulations of recovery of condensate etc are likely to be possible

3233 Energy diagnosis using the energy models A complete energy diagnosis for a given organisation can be carried out according to Figure 311

Chapter 3

80 Version April 2006 SSEIPPCBENE_Draft_1

1) Process analysis

2) Drawing up ofenergy models

3) Theoretical energyindicators

6) Effective energyindicators

4) Energy invoicescollection

7) Areindicators

comparable

9) Areindicators

comparable

8) Reference energyindicators

10) Detecting energysaving actions

11) Cost-benefitanalysis

12) Priority foreconomically viable

actions only13) End of diagnosis

5) Production datacollection

NO

YES

YES

NO

Figure 311 Scheme of energy diagnosis [11 Franco 2005]

Notes bull points 1) 2) 3) are the collection of energy data coming from the electric and thermal models and the

calculation of appropriate energy indicators (eg MJtonne of product kWhm2 etc) bull the same indicators must be calculated from the data of production and for energy supplies points 4)

5) 6) bull such indicators are compared (7) and if they are almost equal then the energy models can be

considered lsquocertifiedrsquo otherwise corrections have to be made to the models themselves until convergence is reached

bull the lsquocertifiedrsquo indicators have now to be compared with energy benchmarks coming from literature energy agencies scientific associations etc If this kind of indicator is still comparable then it means that the lsquoenergy behaviourrsquo of the organisation is in the mainstream average and that it will be difficult to find corrective actions

bull finally if the certified indicators are greater than the benchmarks then energy use in the organisation can be improved It is likely that some energy saving actions will be detected and once only those viable from an economic point of view have been implemented the energy indicators will converge and at this stage the diagnosis can be considered finished

Chapter 3

SSEIPPCBENE_Draft_1 Version April 2006 81

324 Pinch methodology Description of the energy efficiency technique Pinch methodology is a process integration methodology which provides several tools in order to analyse industrial processes in terms of energy saving and pollution prevention according to costbenefits assessment Pinch is a computer-based simulation tool to analyse the minimum energy targets of industrial plants The analysis will identify realistic energy saving projects The starting point is the analysis of involved streams (hot and cold) and utilities (eg fuel steam cooling water) and then the creation of composite curves Each process stream can be represented by a curve in the enthalpytemperature plot moving from the hot temperature to the cold temperature with a fixed heat capacity (CP) All the hot streams could be represented by the hot composite curve obtained by the sum of heat capacity flowrates of streams that are presents in each temperature interval The hot composite curve represents the energy accumulated in the process streams and the temperature range in which it is available Similarly all the cold streams are represented by the cold composite curve The composite curves are plotted in the same HT plot to provide information about the system (see Figure 312) these information are bull minimum process heat required from hot utilities QHmin bull minimum process heat released to cold utilities QCmin bull heat recovery

Hot composite curve

∆∆TTminmin

Cold composite curve

PINCH

QHmin

QCmin Heat recovery

H

T

Figure 312 Hot and cold streams in Pinch methodology [12 Pini 2005]

These are the energy targets for the process From this evaluation it is possible to perform a complete pinch methodology study aimed at identify how these targets could be achieved Heat recovery and integration opportunities are analysed by studying how hot material streams can heat and cold material streams cool the process flows

Chapter 3

82 Version April 2006 SSEIPPCBENE_Draft_1

One of the most important features of this procedure is the template creation The templates are Excel files where the input and output data describing the industrial processes are presented The creation of these files allows us to manipulate the data in effective way so that local operating conditions at other sites can be accurately represented For example the template created for crude distillation unit of a refinery if rightly manipulated should be suitable for describe another similar CDU Pinch methodology has usually the following steps

Steps Main features

Data acquisition PFD Process stream data Utility data

Simulation Template for providing utility and process data

Pinch methodology

Utility assesment (grand composite curve) Minimum energy consumption valuation

Saving calculation Template

Economic aspects Template

Table 35 Steps in Pinch methodology

Achieved environmental benefits especially including improvements in energy efficiency The procedure fits the energy efficiency concept well because it allows the minimum energy consumption of a plant and the subsequent potential saving to be quantified Moreover pinch methodology offers the tools to understand the way the energy savings can be obtained Quite often process industry uses from 10 to 30 extra energy compared to the best design solutions This methodology reduces energy consumption and variable cost of the unit and the CO2 emissions can be reduced to 10 ndash 30

Operational data Some results of the application of pinch methodology are shown in Figure 313 Refinery (nominal capacity is 4550000 tonnesyr) composed of following sections bull primary distillation (DP3) bull catalytic reforming (RC3) bull liquid petroleum gas (LPG) splitter bull isomerisation (ISO) bull dewaxing and hydrodesulphuration (MDDW+HF1) bull visbreaking and thermal cracking (VBampTC) bull merox unit bull sour water stripper (SW1) bull naphta splitting

Chapter 3

SSEIPPCBENE_Draft_1 Version April 2006 83

Olefins and aromatics production (nominal feed is 490000 tonnesyr of virgin naphtha) It is a traditional steam cracking TDI plant (118000 tonnesyr) where toluene diisocyanate is produced via phosgene Olefinic products besides ethylene are propylene cracking gasoline and residuum Aromatic products (benzene toluene dicyclopentadiene) are recovered from cracking gasoline A TDI plant (11800 tonnesyr) is where toluene diisocyanate is produced via phosgene Vinyl chloride monomer (VCM) and polyvinyl chloride (PVC) production - dychloroethane (385000 tonnesyr) is obtained by reaction between HCl ethylene and air Vinyl chloride monomer (280000 tonnesyr) forms from dychloroethane cracking VCM is polymerised in aqueous solution and then dried to produce polyvinyl chloride powder (200000 tonnesyr) Butadiene production (nominal capacity is 60000 tonnesyr) Butadiene is obtained after butanes splitting and absorption in dymethyl-formalamide studies For the VCM plant the possibility of medium pressure steam (MPS) generation has been identified This fact explains the reason why hot utility saving exceeds the 100 value For several processes there is not the chance to save on cold utilities

116 163 165261

39

205 235

008

175273

00

13

1592

000000 000 0629

979

0

Crackin

g

Butadien

e DP3

MDDW+HF1 ISO

RC3

VBampTC

GPL splitt

ingMero

x

Naphtha sp

litting

SW1VCM

PVC TDI

Hot utility saving

Cold utility saving

Figure 313 Energy savings identified by pinch methodology [51 Pini 2005]

Applicability Pinch methodology is widely used for the design of new units and for the retrofitting of existing ones It has many applications such as bull energy analysis of process units bull utility plus heat and power system analysis bull heat exchanger network design and analysis bull total site analysis to optimise process and utility integration bull hydrogen and water system analysis

Chapter 3

84 Version April 2006 SSEIPPCBENE_Draft_1

Pinch is a heavy and expensive tool for companies The implementation of this methodology needs a great number of data and a deep knowledge of the process For some processes eg where a single type of streams (cold or hot) exists pinch methodology is not applicable Experienced professionals are needed to implement Pinch methodology The team consists of Pinch expert process simulation experts experts to handle cost estimations and plant operation experts to comment on the results PC computer and Pinch software are needed

Cross-media effects bull increasing process throughout by eliminating energy bottlenecks

Economics bull implementing study costs are dependent on the size of the analysis starting from

EUR 100000 per case Implemented energy saving cases covers non-investment operational changes and process modification investments which typically have a short payback time In grass root cases Pinch can reduce investment costs

Driving force for implementation Economic savings and environmental benefits are the reasons for using Pinch methodology

Example plants

bull Neste Oil in Finland Porvoo and Naantali refineries (wwwnesteoilcom) bull Borealis Polymers Oy Finland (wwwborealisgroupcom)

Reference information [117 Linnhoff March ] [118 KBC ] [119 Neste Jacobs Oy ] [12 Pini 2005] [51 Pini 2005] [67 Marttila 2005]

325 Benchmarking Description of the energy efficiency technique Benchmarking is simply said to be lsquoimproving ourselves by learning from othersrsquo but can also be defined- eg in following ways bull lsquobenchmarking is about making comparisons with other companys and then learning the

lessons which those companies each show uprsquo (The European Benchmarking Code of Conduct)

bull lsquobenchmarking is the practice of being humble enough to admit that someone else is better at something and being wise enough to learn how to be as good as them and even betterrsquo (American Productivity and Quality Center)

Preface

SSEIPPCBENE_Draft_1 Version April 2006 iii

PREFACE

1 Status of this document Unless otherwise stated references to lsquothe Directiversquo in this document means the Council Directive 9661EC as amended by Directive 200387EC on integrated pollution prevention and control As the Directive applies without prejudice to Community provisions on health and safety at the workplace or any energy efficiency provisions so does this document This document is a working draft of the European IPPC Bureau It is not an official publication of the European Communities and does not necessarily reflect the position of the European Commission

2 The mandate of the work The mandate for this document is threefold a) to implement a special request from the Commission Communication on the

implementation of the European Climate Change Programme (COM(2001)580 final) ECCP concerning energy efficiency in industrial installations The ECCP asks that effective implementation of the energy efficiency provisions of the IPPC Directive are promoted and that a special horizontal BREF addressing generic energy efficiency techniques is prepared

b) gives general guidance to operators and regulators on how to approach and implement

energy efficiency requirements set out in the IPPC Directive and c) be one of several measures foreseen in the European Climate Change Programme aimed at

reducing the emissions of greenhouse gases This document on energy efficiency has links to other Commission instruments eg the following actions have an interface with this document bull Green Paper on Energy Efficiency COM(2005)265 final of 22 June 2005 bull Directive on greenhouse gas emission trading (200387EC) bull Directive on the promotion of cogeneration (20048EC) bull Directive on the energy performance of buildings (200291EC) bull proposal on energy end-use energy efficiency and energy services COM(2003)739 bull the framework Directive for the setting of eco-design requirements for energy using

products EuP (200532EC) bull an Energy Efficiency Toolkit for SMEs developed in the framework of the EMAS

Regulation bull several studies and projects under the umbrella Intelligent Energy ndash Europe and SAVE

which deal with energy efficiency in buildings and industry

3 Relevant legal obligations of the IPPC Directive and the definition of BAT In order to help the reader understand the legal context in which this document has been drafted some of the most relevant provisions of the IPPC Directive including the definition of the term lsquobest available techniquesrsquo are described in this preface This description is inevitably incomplete and is given for information only It has no legal value and does not in any way alter or prejudice the actual provisions of the Directive

Preface

iv Version April 2006 SSEIPPCBENE_Draft_1

The purpose of the Directive is to achieve integrated prevention and control of pollution arising from the activities listed in its Annex I leading to a high level of protection of the environment as a whole including energy efficiency The legal basis of the Directive relates to environmental protection Its implementation should also take account of other Community objectives such as the competitiveness of the Communityrsquos industry thereby contributing to sustainable development More specifically it provides for a permitting system for certain categories of industrial installations requiring both operators and regulators to take an integrated overall look at the polluting and consuming potential of the installation The overall aim of such an integrated approach must be to improve the management and control of industrial processes so as to ensure a high level of protection for the environment as a whole Central to this approach is the general principle given in Article 3 that operators should take all appropriate preventative measures against pollution in particular through the application of best available techniques enabling them to improve their environmental performance including energy efficiency Competent authorities responsible for issuing permits are required to take account of the general principles set out in Article 3 when determining the conditions of the permit These conditions must include emission limit values supplemented or replaced where appropriate by equivalent parameters or technical measures According to Article 9(4) of the Directive these emission limit values equivalent parameters and technical measures must without prejudice to compliance with environmental quality standards be based on the best available techniques without prescribing the use of any technique or specific technology but taking into account the technical characteristics of the installation concerned its geographical location and the local environmental conditions In all circumstances the conditions of the permit must include provisions on the minimisation of long-distance or transboundary pollution and must ensure a high level of protection for the environment as a whole Member States have the obligation according to Article 11 of the Directive to ensure that competent authorities follow or are informed of developments in best available techniques

4 The IPPC Directive and energy efficiency Energy efficiency is not restricted to any one industry sector mentioned in Annex 1 to the Directive as such but is a horizontal issue which is required to be taken into account in all cases In the Directive there are indirect and direct references in energy efficiency in the following articles which will then be explained bull 211 definition of BAT indirect reference bull Annex IV considerations included in BAT direct reference This Directive requires that permits must contain conditions based on Best Available Techniques (BAT) as defined in Article 211 of the Directive to achieve a high level of protection of the environment as a whole A high level of protection means that in issuing the installations permits the regulators have to consider all environmental effects caused by the installation including the effects of energy use Article 211 of the Directive specifies BAT in the following way lsquoBestrsquo shall mean most effective in achieving a high general level of protection of the environment as a whole lsquoAvailablersquo techniques shall mean those developed on a scale which allows implementation in the relevant industrial sector under economically and technically viable conditions taking into consideration the costs and advantages whether or not the techniques are used or produced inside the Member State in question as long as they are reasonably accessible to the operator

Preface

SSEIPPCBENE_Draft_1 Version April 2006 v

lsquoTechniquesrsquo shall include both the technology used and the way in which the installation is designed built maintained operated and decommissioned Furthermore Annex IV specifies what considerations must be taken into account generally or in specific cases when determining best available techniques as defined in Article 2 (11) bearing in mind the likely costs and benefits of a measure and the principles of precaution and prevention The references to energy efficiency in the IPPC Directive are a) Annex IV One of the issues to be taken into account is the consumption and nature of raw

materials (including water) used in the process and their energy efficiency (item 9)b) Article 3 (d) direct reference The Directive requires that Member States shall take the

necessary measures to provide that the competent authorities ensure that installations are operated in such a way that among other things energy is used efficiently (Article 3 (d))

c) Article 61 direct reference In Article 6 it is said that Member States shall take the necessary measures to ensure that an application to the competent authority for a permit includes a description of the raw and auxiliary materials other substances and the energy used in or generated by the installation

d) Article 91 indirect reference In Article 91 concerning conditions of the permit it is stipulated that Member States shall ensure that the permit includes all measures necessary for compliance with the requirements of Articles 3 and 10

e) Article 93 direct reference (amendment) In Article 93 (amendments by Directive 200387EC) concerning limit values it is stipulated that IPPC-permit shall not include an emission value for direct emissions of that gas meaning greenhouse gases specified in Annex 1 to Directive 872003

Furthermore it is stipulated that for activities listed in Annex 1 to Directive 200387EC Member States may choose not to impose requirements relating to energy efficiency in respect of combustion units or other units emitting carbon dioxide on the site Directive 200387EC covers some but not all activities covered by the IPPC Directive This document gives general advice how to implement those requirements

5 Objective of this document Article 16(2) of the Directive requires the Commission to organise lsquoan exchange of information between Member States and the industries concerned on best available techniques associated monitoring and developments in themrsquo and to publish the results of the exchange

The purpose of the information exchange is given in recital 25 of the Directive which states that lsquothe development and exchange of information at Community level about best available techniques will help to redress the technological imbalances in the Community will promote the worldwide dissemination of limit values and techniques used in the Community and will help the Member States in the efficient implementation of this Directiversquo The Commission (Environment DG) established an information exchange forum (IEF) to assist the work under Article 16(2) and a number of technical working groups have been established under the umbrella of the IEF Both IEF and the technical working groups include representation from Member States and industry as required in Article 16(2)

Preface

vi Version April 2006 SSEIPPCBENE_Draft_1

The aim of this series of documents is to reflect accurately the exchange of information which has taken place as required by Article 16(2) and to provide reference information for the permitting authority to take into account when determining permit conditions By providing relevant information concerning best available techniques these documents should act as valuable tools to drive environmental performance including energy efficiency The special target of this document is to provide a comprehensive energy management structure which makes it possible for companies to demonstrate their energy efficiency and competent authorities to verify it This general structure will later be tailored for different sectors in sectoral BREFs The background and mandate of this work concerning generic energy efficiency techniques for industry differs from other BREFs in the sense that this document is prepared in the IPPC context but it can be used in a broader scope

6 Information Sources This document represents a summary of information collected from a number of sources including in particular the expertise of the groups established to assist the Commission in its work and verified by the Commission services All contributions are gratefully acknowledged

7 How to understand and use this document The information provided in this document is intended to be used as an input to the recommendations for goodbest practices to contribute energy efficiency in IPPC installations When determining BAT and setting BAT-based permit conditions account should always be taken of the overall goal to achieve a high level of protection for the environment as a whole including energy efficiency The rest of this section describes the type of information that is provided in each section of this document Chapter 1 provides general information on the basics of energy and thermodynamics It explains main features of energy and principles of thermodynamics as an introduction for understanding energy applications in industry and their restrictions Chapter 2 provides information on the definitions of energy efficiency relevant for industry and how to develop indicators to monitor energy efficiency Furthermore it deals with different aspects which influence energy efficiency some of them which company has control and some of them not It also gives examples how different system boundaries influence the energy efficiency Chapter 3 provides information on good energy management in industrial installations in broad terms It explains why good structured management is important and which issues will be considered and taken into account in a good system It covers the elements which are crucial to manage energy issues efficiently both from an environmental and economical point of view It gives examples of good management structures approaches audits methodologies and other tools which could be implemented to improve energy efficiency Systematic and transparent way to deal with energy issues is essential to reach best economical and environmental results Chapter 4 provides information on generic energy producing and using systems and unit operations which can be found in several industries It describes energy saving techniques related to these systems (eg steam system) and unit operations (eg motors) The approach is to describe different strategies to improve energy efficiency in these systems and also describe commonly used energy saving techniques (eg heat recovery) separately

Preface

SSEIPPCBENE_Draft_1 Version April 2006 vii

Chapter 5 recommends the best practices to be used in companies to manage energy issues Since the best available techniques change over time this document will be reviewed and updated as appropriate All comments and suggestions should be made to the European IPPC Bureau at the Institute for Prospective Technological Studies at the following address

Edificio Expo cInca Garcilaso sn E-41092 Sevilla Spain Telephone +34 95 4488 284 Fax +34 95 4488 426 e-mail JRC-IPTS-EIPPCBceceuint Internet httpeippcbjrces

SSEIPPCBENE_Draft_1 Version April 2006 ix

Best Available Techniques Reference Document on ENERGY EFFICIENCY TECHNIQUES

EXECUTIVE SUMMARYI PREFACE III SCOPE XVII 1 GENERAL FEATURES ON ENERGY 1

11 Introduction 1 111 Forms of energy 1 112 Energy transfer and storage 2 113 Energy losses 3 114 Exergy 3

12 Principles of thermodynamics 4 121 Characterisation of systems and processes 4 122 Forms of energy storage and transfer 4 123 Properties enthalpy and specific heat 5 124 Properties entropy and exergy 6

13 First and second laws of thermodynamics 7 131 First law of thermodynamics ndash energy balance 7

1311 Energy balance for closed systems 7 1312 Energy balance for open systems7 1313 Calculation of internal energy and enthalpy changes8 1314 First law efficiencies thermal efficiency and coefficient of performance 8

132 Second law of thermodynamics - entropy balance 9 133 Combination of the first and second laws - exergy balance 10

1331 Exergy balance for a closed system 10 1332 Exergy balance for an open system10 1333 Calculation of flow exergy changes11 1334 Second law efficiency exergetic efficiency11

14 Property diagrams tables databanks and computer programs 12 141 Pressure-temperature diagram 12 142 Pressure-specific volume and temperature-specific volume diagrams 13 143 Temperature-entropy diagram 14 144 Enthalpy-entropy diagram 15 145 Property tables databanks and simulation programs 15

15 Identification of inefficiencies 16 151 Case 1 Throttling devices 17 152 Case 2 Heat exchangers 19 153 Case 3 Mixing processes 21

2 ENERGY EFFICIENCY 27 21 Definitions of energy efficiency 27 22 Energy efficiency indicators in industry 28

221 Production processes 29 222 Energy intensity factor and energy efficiency index 29 223 Energy efficiency in production units 30 224 Energy efficiency of a site 34

23 Issues to be considered when defining energy efficiency indicators 35 231 System boundaries 35

2311 Definition of the system boundary35 2312 Examples of system boundaries36 2313 Some remarks on system boundaries 40

232 Other items to be decided by the company 41 233 Structural issues 45

24 Examples of application of energy efficiency 48 241 Mineral oil refineries 48 242 Ethylene cracker 49 243 VAM production 50 244 A rolling mill in a steel works 51 245 Heating of premises 53

3 ENERGY MANAGEMENT IN INDUSTRIAL INSTALLATIONS 55 31 The structure and the content of energy management 55

x Version April 2006 SSEIPPCBENE_Draft_1

311 General features and factors 55 312 Commitment of the top management 58 313 Planning 59

3131 Initial energy audit 59 3132 Energy performance targets 60 3133 Action plan 61

314 Doing 61 3141 Structures and responsibilities 62 3142 Awareness raising and capacity building62 3143 Communication and motivation63

315 Checking 63 3151 Monitoring and measurement 63 3152 Records 64 3153 Periodic energy audits64

316 Acting 64 317 Examples of energy management systems and its implementation 65

32 Methodologies and tools for energy use optimisation and energy efficiency 65 321 Energy audits 65

3211 Audit models66 32111 The scanning models67 32112 The analysing models68 32113 The technical coverage of energy audit models 69

3212 Audit tools 71 322 Energy monitoring 72 323 Energy models 73

3231 Example 1 Electric energy models74 3232 Example 2 Thermal energy models77 3233 Energy diagnosis using the energy models 79

324 Pinch methodology 81 325 Benchmarking 84 326 Assessment methods 88

3261 Time series comparison 88 3262 Comparison with theoretical approaches 89 3263 Benchmarks approaches90

327 Qualification of components in representative conditions 91 328 Cost calculations 93 329 Checklists 93 3210 Good housekeeping 93 3211 E-learning 93

33 Energy services company (ESCO) concept 93 34 Public schemes and tools to motivate energy saving in industry 94

341 Tax deductions for energy saving investments 94 342 Ecology premium 95 343 Support for demonstration projects in energy technology 96 344 Cogeneration certificates (blue certificates) 96 345 Energy planning regulation 97 346 Benchmarking covenant 98 347 Audit covenant 99 348 Energy saving certificates (white certificates) 100 349 EMAT - energy managerrsquos tool 102 3410 Energy saving agreements 103

4 APPLIED ENERGY SAVING TECHNIQUES 105 41 Introduction 105 42 Combustion 106

421 Choice of combustion techniques 106 422 Strategies to decrease losses in general 107 423 High temperature air combustion technology (HiTAC) 111

43 Steam systems 114 431 General features of steam 115 432 Measures to improve steam system performance 117 433 Use of economisers to preheat feed-water 119 434 Prevention removal of scale deposits on heat transfer surfaces 120 435 Minimising blowdown 122 436 Recovering heat from the boiler blowdown 124

SSEIPPCBENE_Draft_1 Version April 2006 xi

437 Implementing a control and repairing programme for steam traps 126 438 Collecting and returning condensate to the boiler for re-use 128 439 Re-use of flash steam 130 4310 Insulation on steam pipes and condensate return pipes 131 4311 Installation of removable insulating pads on valves and fittings 132 4312 Use of flash steam on the premises through recovery of condensate at low pressure 133 4313 Installing an air preheater 134 4314 Minimising boiler short cycling losses 136

44 Power production 137 45 Cogeneration 138

451 Different types of cogeneration 138 452 CHP in soda ash plants 144 453 Stationary reciprocating engine solutions 145 454 Trigeneration 148 455 District cooling 151

46 Waste heat recovery 154 461 Direct heat recovery 155 462 Heat pumps 157 463 Surplus heat recovery at a board mill 161 464 Mechanical vapour recompression (MVR) 163 465 Acid cleaning of heat exchangers 166 466 Heat exchangers with flashed steam - design 168

47 Electric motor driven systems 171 48 Compressed air systems 177

481 General description 177 482 Improvement of full loadno load regulation system 181 483 Variable speed drive technology (VSD) 182 484 Optimising the pressure level 184 485 Reducing leakages 186

49 Pumping systems 187 491 General description 187 492 Choice between steam turbine driven pumps and electrical pumps 188 493 Vacuum pumps replacing steam ejectors 192

410 Drying systems 193 4101 General description 193 4102 Techniques to reduce energy consumption 195

41021 Mechanical processes 195 41022 Computer-aided process controlprocess automation195 41023 Selecting the optimum drying technology 196

411 Process control systems 196 4111 General features 196 4112 Energy management and optimisation software tools 200 4113 Energy management for paper mills 201 4114 Fluidised bed boiler combustion optimisation 204 4115 Steam production and utilisation optimisation using a model predictive controller 205

412 Transport systems 207 413 Energy storage 211

5 BEST PRACTICES 213 51 Generic best practices 214 52 Energy efficiency indicators 214 53 Energy management structure and tools 215 54 Techniques to improve energy efficiency 216

541 Combustion 216 542 Steam systems 217 543 Cogeneration 217 544 Heat recovery 218 545 Electric motor drive systems 218 546 Compressed air systems 219 547 Pumping systems 219 548 Drying systems 219 549 Transport systems 219

6 CONCLUDING REMARKS 221

xii Version April 2006 SSEIPPCBENE_Draft_1

7 REFERENCES 223 8 GLOSSARY 227 9 ANNEXES 233

91 Annex 1 233

SSEIPPCBENE_Draft_1 Version April 2006 xiii

List of figures Figure 11 Pressure-temperature diagram 12 Figure 12 P-v diagram 13 Figure 13 T-v diagram 14 Figure 14 Temperature-entropy diagram 14 Figure 15 Enthalpy-entropy diagram 15 Figure 16 Steam throttling process 18 Figure 17 T-s and h-s diagrams for the steam throttling process of the example 18 Figure 18 Counterflow heat exchanger 20 Figure 19 Reheating process of a steam flow 20 Figure 110 T-s and h-s diagram for the steam reheating process of the example 21 Figure 111 IiRT0 versus molar fraction of one component in the mixture 22 Figure 112 Mixing chamber of two flows 23 Figure 113 T-s diagram for the mixing process of the example 24 Figure 21 Energy vectors in a simple production unit 30 Figure 22 Energy vectors in a production unit 32 Figure 23 Inputs and outputs in a site 34 Figure 24 System boundary ndash old electric motor 36 Figure 25 System boundary ndash new electric motor 37 Figure 26 System boundary ndash electric motor + old pump 37 Figure 27 System boundary ndash electric motor + new pump 38 Figure 28 Electric motor + new pump with constant output 38 Figure 29 New electric motor new pump and old heat exchanger 39 Figure 210 New electric motor new pump and two heat exchangers 40 Figure 211 Inputs and outputs for a vinyl acetate monomer (VAM) plant 50 Figure 212 Flow chart of a rolling mill 51 Figure 213 Specific energy consumption in a rolling mill 52 Figure 214 Specific energy consumption in a rolling mill 53 Figure 215 Energy consumption depending on outdoor temperature 53 Figure 216 Energy consumption depending on outdoor temperature 54 Figure 31 The plan-do-check-act-cycle (PDCA) 57 Figure 32 Continuous improvement of an energy management system 57 Figure 33 Basic energy auditing models 66 Figure 34 The properties of energy audit models 66 Figure 35 Coverage of an industrial site energy audit 69 Figure 36 Coverage of a district heating connected to a residential building energy audit 70 Figure 37 Coverage of a CHP plant energy audit 70 Figure 38 Structure of a monitoring system 72 Figure 39 Monitoring process 73 Figure 310 Power factor of a device depending on the load factor 75 Figure 311 Scheme of energy diagnosis 80 Figure 312 Hot and cold streams in Pinch methodology 81 Figure 313 Energy savings identified by pinch methodology 83 Figure 314 Mechanism when an ESCO is involved 100 Figure 41 Energy balance of a combustion installation 107 Figure 42 Working principle for regenerative burners 111 Figure 43 Different regions of combustion 112 Figure 44 The net heat output of test furnaces resulted by both conventional and HiTAC burners 113 Figure 45 Distribution of the energy content of steam in the sensible and latent component depending on

absolute pressure 116 Figure 46 Back-pressure plant 139 Figure 47 Extraction condensing plant 139 Figure 48 Gas turbine heat recovery boiler 140 Figure 49 Combined cycle power plant 140 Figure 410 Reciprocating plant 141 Figure 411 Comparison between efficiency of condensing power and combined heat and power plant142 Figure 412 Trigeneration compared to separate energy production 148 Figure 413 Trigeneration enables optimised plant operation around the year 149 Figure 414 District cooling in the winter by free cooling technology 152 Figure 415 District cooling by absoption technology in the summer 152 Figure 416 Diagram of a compression heat pump 158 Figure 417 Diagram of an absorption heat pump 159

xiv Version April 2006 SSEIPPCBENE_Draft_1

Figure 418 Heat recovery system connected to the district heating system 162 Figure 419 Simple MVR installation 163 Figure 420 COP versus temperature lift for a typical MVR system 164 Figure 421 Process scheme of Eurallumina alumina refinery 166 Figure 422 Operative cycle of heaters 167 Figure 423 A section of the heater 169 Figure 424 Scales in the tube bundle 170 Figure 425 A compressor motor with a rated output of 24 MW 173 Figure 426 Some methods of capacity control of a centrifugal pump 175 Figure 427 Performance of compressors with different controls 175 Figure 428 Pump power consumption 176 Figure 429 Fans with different controls 176 Figure 430 Compressed air system 178 Figure 431 Energy flow diagram for an inefficient compressed air station 179 Figure 432 Compressor lifecycle costs 183 Figure 433 Different kinds of compressor control 184 Figure 434 Steam distribution scheme of the alumina refinery 189 Figure 435 Bandwidths for the specific secondary energy consumption of different types of dryer when

vaporising water 194 Figure 436 Structure of an energy management tool 200 Figure 437 Paper mill energy management (system layout) 202 Figure 438 Tracking deviations from optimum consumption 202 Figure 439 Steam flow depending on fuel and time 204 Figure 440 Variable definition matrix 206

Scope

SSEIPPCBENE_Draft_1 Version April 2006 xv

List of tables Table 11 Some values of the derivatives 22 Table 12 Maximum values for mistures 23 Table 31 Energy management matrix 56 Table 32 A simple electric model 75 Table 33 Data ina thermal energy model (generators side) 77 Table 34 Data in a thermal energy model (users side) 78 Table 35 Steps in Pinch methodology 82 Table 36 Information template for energy efficiency motivation tools 94 Table 37 Areas covered in the application 102 Table 41 The template for information on energy efficiency techniques 105 Table 42 Higher and lower calorific values of certain fuels 107 Table 43 Differences in heat transfer 121 Table 44 Energy content of blowdown 123 Table 45 Recovered energy from blowdown losses 125 Table 46 Various operating phases of steam traps 126 Table 47 Operating factors for steam losses in steam traps 127 Table 48 Load factor for steam losses 127 Table 49 Percentage of total energy present in the condensate at atmospheric pressure and flash steam

129 Table 410 Percentage of total energy present in the condensate at atmospheric pressure and flash steam

130 Table 411 Heat losses per metre of pipes in function of the operating temperature and insulation

thickness 132 Table 412 Calculation of the Siegert Co-efficient for different types of fuel 135 Table 413 Technical data for the Barajas Airport trigeneration plant 151 Table 414 Components of an electric motor drive system 171 Table 415 Possible energy saving measures in compressed air systems 180 Table 416 Leakage costs 186 Table 91 Saturated water properties 234 Table 92 Superheated water properties I 235 Table 93 Superheated water properties II 236

Scope

SSEIPPCBENE_Draft_1 Version April 2006 xvii

SCOPE This document together with other BREFs in the series (see list on the reverse of the title page) are intended to cover the energy efficiency issues under IPPC Directive This document also responds to the special request from the Commission Communication on the implementation of the European Climate Change Programme (COM(2001)580 final) ECCP concerning energy efficiency in industrial installations The ECCP asks that effective implementation of the energy efficiency provisions of the IPPC Directive are promoted and that a special horizontal BREF addressing generic energy efficiency techniques is prepared The target of this document is to provide information on how to improve energy efficiency in industrial installations by giving generic guidance on how to approach assess implement and deal with energy efficiency related issues along with corresponding permit and supervising procedures Many of the proposed measures tools and methodologies dealt with may also be implemented in non-IPPC installations This document deals with generic energy efficiency techniques and best practices which can be applied in several industrial sectors without duplicating the work done in sectoral BREFs However it can feed other work that is in progress with information and ideas The coverage of this document is as follows bull industrial sectors which use or produce energy and apply generic techniques which are

possible to transfer to other sectors are covered bull it does not develop or conclude on sector specific techniques but will use examples from

various industry sectors to derive generic conclusions bull equipment (eg pumps fans) as parts of systems and installations are dealt with without

drawing conclusions which could conflict with EuP implementing measures bull it does not respond to fuel specific (eg bio fossil waste) issues bull the system boundary is set in most cases round the site but in some cases also smaller or

larger boundaries are considered The main question to be answered in this document is the following How to demonstrate if energy is used and produced efficiently

For finding answers to this question this document deals with the following issues bull what are appropriate definitions for energy efficiency bull what are and how to use energy efficiency indicators bull what methodologies techniques etc contribute to good energy management bull what are the possible measures both techniques and practices to improve energy

efficiency bull what are possible motivation tools To answer all the above-mentioned questions this document deals with the following issues bull energy management including different types of auditing bull methodologies bull monitoring bull indicators and measurements bull applied techniques and good practices

xviii Version April 2006 SSEIPPCBENE_Draft_1

In order to further clarify the scope the following can be said bull because energy efficiency means different things for different stakeholders clarification on

what energy efficiency means in this document is required First a distinction needs to be made between energy efficiency at the macro level (eg national) and at the micro level (eg company level) In this document only the latter is discussed

bull energy efficiency is dealt with from an industrial perspective within the installation boundaries without considering a productrsquos life cycle This is in line with the IPPC Directive which deals with production and not with products The fuel by which energy is produced is also not considered in this document

bull this document deals with production activities in industrial installations but energy demand of products is outside the scope Furthermore fuel specific issues are neither dealt with in this document

bull those techniques and measures to improve energy efficiency which are sector specific are not dealt within here but in sectoral BREFs For example it exists a BREF on large combustions plants where energy efficiency is also covered

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 1

1 GENERAL FEATURES ON ENERGY [2 Valero-Capilla 2005] [3 FEAD and Industry 2005] [97 Kreith 1997] This chapter deals with the basics of energy and thermodynamics It explains the main features of energy and the principles of thermodynamics as an introduction for understanding energy applications and their restrictions in industry There is a lot of generic information on thermodinamics available in the general literature

11 Introduction Energy is needed to fulfil the necessary or imagined needs of people To do this energy is needed directly (eg heating lighting) or indirectly (eg energy in products) Industry needs energy as one production factor to manufacture goods and provide services to the society Decoupling energy demand and supply is a challenging task

111 Forms of energy Energy can take a wide variety of forms There are five main forms of energy generally required in industry bull chemical energy the energy that bonds atoms or ions together (eg fuels) bull mechanical energy associated with motion bull thermal energy (or heat) the internal motion of particles of matter bull electrical (or electromagnetic) energy associated with the electrical charges and the

movement of them bull nuclear energy energy in the nuclei of atoms which can be released by fission or fusion of

the nuclei Chemical energy is stored in fuels and can be converted directly to mechanical energy (combustion engines) or to thermal energy (direct process heating) However most often the chemical energy is converted to a more usable form generally either to electrical energy or mechanical energy to drive machines or thermal energy as the source of a process

Mechanical energy can exist into two states kinetic or potential Kinetic energy is the energy that moving objects have due to their motion For example it can be an alternative motion (eg a piston) a rotary motion (eg transmission shaft) or a waterfall Potential energy is the energy stored in an object due to its position for instance water stored by a dam Thermal energyheat is quantified by temperature It can be created by chemical reactions such as burning nuclear reactions electromagnetic dissipation (as in electric stoves) or mechanical dissipation (such as friction)

Electrical energy or electromagnetic energy is a form of energy present in any electric field or magnetic field or in any volume containing electromagnetic radiation Nuclear energy will not be dealt within this document Energy can also be expressed as primary and secondary energies usually for statistical purposes Primary energy is energy contained in raw fuels and any other forms of energy received by a system as input to the system Primary energies are transformed to secondary energies in energy conversion processes to more convenient forms of energy such as electrical energy

Chapter 1

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112 Energy transfer and storage Transfer Energy cannot be created or destroyed Energy can only be converted from one form to another (first law of thermodynamics see Section 131) Energy is converted to make it more useful for different purposes in industry and all society Energy found in fossil fuels solar radiation or nuclear fuels needs to be converted into other energy forms such as electrical propulsive or cooling to be useful Energy conversion is any process of converting energy from one form to another The efficiency of a converting machine characterises how well it can convert the energy Energy conversion can be done by eg the following means bull electricity can be turned into mechanical energy by an electrical motor bull inversely mechanical energy can be converted into electricity by an alternator bull thermal energy can be transformed into mechanical energy by a turbine bull electricity can be converted into heat by a resistance bull chemical energy can be turned into heat during a chemical reaction and also into (kinetic)

mechanical energy and heat for instance in an explosion bull an internal combustion engine converts chemical energy in the gasoline to the propulsive

energy that moves a car bull a solar cell converts solar radiation into electrical energy that can then be used to light a

bulb or power a computer Storage The storage of different forms of energy (see Section 111) are quite different Some are difficult or even impossible to store as such Electricity can hardly be stored as such Batteries store potential electrical energy but in fact chemically Mechanical and thermal energies can be stored in the medium term as potential energy water damshot water tanks but in general they are not so easy to store One of the most convenient ways for storing energy is undoubtedly as chemical energy in a material It can be stored for a long and even sometimes very long time It can be transported and it is often easy and quick to implement The most important chemical sources of energy are the fuels

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 3

113 Energy losses Energy losses are very different according to the transformation it undergoes Furthermore the transformation is neither total nor unique eg an electrical motor also generates heat Losses are unavoidable to some extent (second law of thermodynamics see Section 132) The following examples illustrate the losses from a combustion plant and from electricityheat conversion Combustion plant bull the first energy losses are due to incomplete combustion of the fuel Part of the fuel is not

burnt at all or only partially and in this case produces other reactants (such as CO2) than the ones resulting from complete combustion This is an incomplete conversion of chemical energy into thermal energy

bull some other losses are due to an incomplete transfer of the heat of the combustion gases to the watersteam of the boiler losses through the lagging of the combustion chamber and of the boiler losses to the air by the flue-gas losses to the air via the ashes

bull the heat of the combustion gases is mostly transferred to the steam cycle but part of it is transferred to the air instead of the fluid which is required (watersteam)

bull similarly if heat is exported via a heat exchanger there will be some losses by transfer of part of it to the air instead of to the secondary fluid

bull when steam is sent to a turbo generator set part of its energy is transferred to the air by direct heat losses and mechanical frictions in the turbo generator set However most of the losses here are due to the latent heat which is released by steam when condensed at the cold source The latent heat is the energy released or absorbed during a change of state (released when passing from the gaseous state of steam to the liquid state of water) Of course the losses are significantly reduced if this energy can be used as happens in the case of cogeneration

Electricityheat conversion bull when turning electricity into heat nearly 100 of the electricity input will be turned into

heat However converting the heat released by the combustion of a fuel into electricity can typically result a conversion efficiency of about 35 of the fuel energy input Using electricity just for making heat is not considered to be an efficient use of energy since the electricity which is used was most probably made from heat in a thermal cycle So it is much more beneficial when possible to use a heat source directly than to convert heat into electricity then electricity into heat even if the second transformation is made with high efficiency

114 Exergy The term lsquoexergyrsquo is used to describe differences in energy quality in other words exergy shows the maximum useful work obtainable in the system The exergy content of a system indicates its distance from the thermodynamic equilibrium See Section 124 and 133 For instance 1 GJ of steam at 400 degC40 bar contains the same energy as 1 GJ of water at 40 degC but different exergy The usefulness of these energies are really different on the one hand there is 300 kg of steam on the other 6 tonnes of water and steam at 40 bar can be used for generating electricity moving mechanical equipment heating etc but there is little use for water at 40 degC The exergy of low temperature energies can be raised by eg heat pumps

Chapter 1

4 Version April 2006 SSEIPPCBENE_Draft_1

12 Principles of thermodynamics Thermodynamics is the physics that deals with the relationships and conversions between heat and other forms of energy 121 Characterisation of systems and processes A system (as a thermodynamic concept) is the quantity of matter within the prescribed boundary under consideration everything external to the system is called the surroundings Systems may be considered as closed or open A system can be considered closed if there is no interchange of matter between the system and the surroundings If there is an interchange the system is considered to be open A very important class of systems that is frequently encountered by engineers is steady-flow systems A steady-flow system can be defined as any fixed region-of-space system through which a fluid flows and the properties of this fluid either internal to the system or at its boundaries do not change as time passes Typical examples include air compressors gas turbines steam turbines boilers pumps heat exchangers etc All these devices have in common that each has one or more fluid streams entering and leaving Devices with these characteristics are also known as steady-state steady-flow systems steady-flow control volumes and flow systems Any characteristic of a system is called property Temperature volume pressure or mass are some of the most familiar examples

122 Forms of energy storage and transfer The energy of a system consists of the kinetic potential and internal energies expressed as

mgzmCUPTKNUU PK ++=++=2

2

(J) Equation 11

Where

bull U is the internal energy which is associated with the microscopic forms of energy ie to the motion position and internal state of the atoms or molecules of the substance

bull KN is the kinetic energy which is associated to the motion of the system as a whole relative to some reference frame

bull C is the velocity of the system relative to some fixed reference frame bull m is the mass of the body in motion

bull PT is the change in gravitational potential energy which is associated with the position of the system as a whole (elevation) in the earthrsquos gravitational field

bull g is the gravitational acceleration

bull z is the elevation of the centre of gravity of a system relative to some arbitrarily selected reference frame

Thermal energy is a huge drain of energy when compared with kinetic or potential energies Therefore in many energy analyses these two last energies may be disregarded Energy storage Energy can be stored in numerous forms (some more information in Section 112) The most important encountered forms in thermodynamic applications are internal kinetic and potential energy Other forms of energy such as magnetic electric and surface tension effects are significant only in some specialised cases and will not be considered here

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 5

Energy transfer The forms of energy discussed above which constitute the total energy of a system are static forms of energy and can be stored in a system However energy can also be transformed from one form to another and transferred between systems For closed systems energy can be transferred through work and heat transfer Heat and work are not properties because they depend on the details of a process and not just the end states bull heat (Q) can be defined as energy in transit from one mass to another because of a

temperature difference between the two It accounts for the amount of energy transferred to a closed system during a process by means other than work The transfer of energy occurs only in the direction of decreasing temperature Heat can be transferred in three different ways conduction convection and radiation Conduction is the transfer of energy from the more energetic particles of a substance to the adjacent particles that are less energetic due to interactions between the particles Conduction can take place in solids liquids and gases Convection is the energy transfer between a solid surface at a certain temperature and an adjacent moving gas or liquid at another temperature Finally thermal radiation is emitted by matter as a result of changes in the electronic configurations of the atoms or molecules within it The energy is transported by electromagnetic waves and it requires no intervening medium to propagate and can even take place in vacuum

bull work (W) has the following thermodynamic definition work is done by a system on its surroundings if the sole effect on everything external to the system could have been the raising of a weight Like heat work is also energy in transit

123 Properties enthalpy and specific heat Enthalpy A property related to internal energy U pressure p and volume V is enthalpy H defined by

H = U + pV (J) Equation 12 Or per unit of mass using specific internal energy u and specific volume v (internal energy and volume per unit of mass) as follows h = u + pv (J) Equation 13 Specific heat capacity The property specific heat capacity C (commonly named specific heat) relates energy and temperature The specific heat is defined as the energy required to raise the temperature of a unit mass of a substance by one degree Two different specific heats are usually considered in thermodynamics specific heat at constant volume CV and specific heat at constant pressure CPSpecific heat at constant volume CV expresses the energy required to raise the temperature of the unit mass of a substance by one degree as the volume is maintained as constant The energy required to do the same to the pressure being maintained as constant is the specific heat at constant pressure CP CV and CP are expressed as follows

vv T

uC

partpart

= (JK) Equation 14

pp T

hC

partpart

= (JK) Equation 15

Chapter 1

6 Version April 2006 SSEIPPCBENE_Draft_1

The values of internal energy enthalpy and heat capacities can be calculated as shown in Section 1313 and they are extensively available through property tables databases and programs for a great variety of substances as explained in Section 145

124 Properties entropy and exergy Entropy The concept of entropy is very important to state the second law of thermodynamics in (see Section 132) a general and usable form When two stable states of a system are connected by different internally reversible processes the integral of the heat interchanged over its temperature is found not to be dependent on process path This proves the existence of the function called entropy which only depends on the state of the properties of the system The change of entropy is defined as follows

(JK) Equation 16

Entropy is an abstract property and can be viewed as a measure of disorder Unlike energy entropy is a non-conserved property However entropy is easily calculated following procedures like those explained in Section 143 Thermodynamic databanks as explained in Section 144 include values of entropy for many substances mixtures and pressure and temperature ranges Exergy Exergy of a thermodynamic system is the maximum theoretical useful work (shaft work or electrical work) obtainable as the system is brought into complete thermodynamic equilibrium with the thermodynamic environment while the system interacts with this environment only (some more information can be found in Section 114) A system is said to be in the dead state when it is in thermodynamic equilibrium with its surroundings In the dead state a system is at the temperature and pressure of its surroundings it has no kinetic or potential energy and it does not interact with the surroundings Exergy can be defined as well as a measure of the departure of the state of a system from the environment Once the environment is specified a value can be assigned to exergy in terms of property values for the system only and exergy can be regarded as a property of the system The value of exergy as defined in Equation 17 cannot be negative and is not conserved but destroyed by irreversibilities The specific exergy on a unit mass basis is e = (u-u0) + p0 (v-v0) ndash T0(s-s0) + C22 + gz (J) Equation 17 Where bull 0 denotes the dead state When a mass flows across the boundaries of a control volume there is an exergy transfer accompanying the mass and work flows This is named lsquospecific flow exergyrsquo or lsquophysical exergyrsquo of a material stream and is given by e = (h-h0) - T0 (s-s0) + C22 + gz (J) Equation 18 Flow exergy is commonly used in the analysis of open systems and calculating it is as simple as any other thermodynamic property as explained in Section 14

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 7

13 First and second laws of thermodynamics The two fundamental and general laws of thermodynamics are (1) energy is conserved and (2) it is impossible to bring about any change or series of changes The sole net result of which is the transfer of energy as heat from a low to a high temperature In other words heat will not flow from low to high temperatures by itself A thermodynamic process will not occur unless it satisfies both the first and the second laws of thermodynamics

131 First law of thermodynamics ndash energy balance The first law of thermodynamics is the general principle of physics and it states that energy is conserved Although the law has been stated in a variety of ways all have essentially the same meaning The following are examples of typical statements bull whenever energy is transformed from one form to another energy is always conserved bull energy can neither be created nor destroyed bull the total sum of all energies remains constant for a given system bull the net energy in the form of heat added or removed from a system that operates in a cyclic

manner equals the net energy in the form of work produced or consumed by the system bull the value of the net work done by or on a closed system undergoing an adiabatic process

between two given states depends solely on the end states and not on the details of the adiabatic process

1311 Energy balance for closed systems For a closed system the first law implies that the change in system energy equals the net energy transfer to the system by means of heat and work That is U2 ndash U1 = Q - W (J) Equation 19 In systems undergoing cycles the net work output equals the net heat transfer to the cycle Wcycle = Qin - Qout (J) Equation 110

1312 Energy balance for open systems Most applications of engineering thermodynamics are conducted on a controlled volume basis In such cases the conservation of the mass principle must be applied The time rate of accumulation of mass within the control volume equals the difference between the total rates of mass flow in and out across the boundary as shown below

sumsum minus=2

21

1 mmdtdm

(kgs) Equation 111

The energy rate balance for such a system is

++minus

+++minus= 2

22

22

1

21

11

22gzChmgzChmWQ

dtdU

(W) Equation 112

Chapter 1

8 Version April 2006 SSEIPPCBENE_Draft_1

For steady-flow systems the mass flowrates and the rates of energy transfer by heat and work are constant with time

sumsum =2

21

1 mm (kgs) Equation 113

Hence at steady state the first law of thermodynamics can be expressed as

++minus

++=minus 2

22

22

1

21

11

22gzChmgzChmWQ (W) Equation 114

1313 Calculation of internal energy and enthalpy changes The change in internal energy and enthalpy for an ideal gas during a process from state 1 to state 2 is determined as follows

int=minus=∆2

112 )( dTTCuuu v (J) Equation 115

int=minus=∆2

112 )( dTTChhh p (J) Equation 116

The values of CV and CP can be obtained through tables databases and programs for many substances as explained in Section 123 For incompressible substances (those whose specific volume or density is constant) CV = CPand following equations can be applied

(J) Equation 117

Where bull Cav is a C value at the average temperature for small temperature intervals ∆h = ∆u + v∆P (J) Equation 118

1314 First law efficiencies thermal efficiency and coefficient of performance

The thermal efficiency η measures the performance of a heat engine and can be defined as the fraction of the heat input that is converted to net work output

in

outnet

QW =η (-) Equation 119

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 9

It can also be expressed as

in

out

QQ

minus= 1η (-) Equation 120

For a power cycle operating between thermal reservoirs at temperatures TH and TC(T temperature H hot and C cold) the thermal efficiency is

H

C

QQ

minus= 1η (-) Equation 121

The maximum efficiency that can be achieved is given by the Carnot efficiency which is shown in Equation 122 below

H

C

TT

minus= 1η (-) Equation 122

The equations above are also applicable to refrigeration and heat pump cycles operating between two thermal reservoirs but for these QC represents the heat added to the cycle from the cold reservoir at temperature TC and QH is the heat discharged to the hot reservoir at temperature TH More informative coefficients are perhaps the Coefficients of Performance COP of any refrigeration cycle COPR and heat pump cycles COPHP given by

CH

CR QQ

QCOP

minus= (-) Equation 123

CH

HHP QQ

QCOPminus

= (-) Equation 124

Unlike the thermal efficiency the value of COP can be greater than unity This means that the amount of heat removed from the refrigerated space can be greater than the amount of work input

132 Second law of thermodynamics - entropy balance The second law of thermodynamics shows which types of transformations are possible or not and in which direction they occur Like the first law the second can be assumed in many different ways and some of them are listed below bull it is not possible to construct a heat engine which produces no other effect than the

exchange of heat from a single source initially in an equilibrium state and the production of work Heat engines must always reject heat to a thermal-energy reservoir

bull no cyclical device can cause heat to transfer from thermal-energy reservoirs at low temperatures to reservoirs at high temperatures with no other effects

bull the total entropy of an engine and all of the surrounding components that interact with the engine must increase when the heat engine is not completely reversible

bull the only processes that can occur are those for which the entropy of the isolated system increases This statement is known as the increase of entropy principle

Chapter 1

10 Version April 2006 SSEIPPCBENE_Draft_1

133 Combination of the first and second laws - exergy balance The first and second laws can be combined into a form that is useful for conducting analyses of exergy work potential and the second law efficiencies among others This form also provides additional insight into systems their operation and optimisation

1331 Exergy balance for a closed system The exergy balance for a closed system is obtained with the combination of the energy and entropy balances The exergy change in a closed system is equal to the sum of the exergy transfer accompanying heat the exergy transfer accompanying work minus the destruction of exergy The final equation is

[ ]

ndestructioExergy

workngaccompanyi

transferExergy

heatngaccompanyi

transferExergy

jchangeExergy

TVVpWQTT

EEE σδ 0120

2

1

012 )(1 minusminusminusminus

minus=minus=∆ int 44 344 21

443442143421

(J) Equation 125

bull T0 denotes the temperature at ambient conditions bull p0 denotes pressure at ambient conditions bull Tj is the surface temperature where the heat transfer takes place The term T0σ accounts for the destruction of exergy or thermodynamic irreversibility and is often denoted as I The value of exergy destruction is always positive and ideally zero when no irreversibilities are present within the system As explained in this section if the principal task of any energy analyst is to pinpoint irreversibilities it is quite logical to make use of exergy balances instead of the entropy ones This is because exergy has the familiar units of energy rather than units of energy over temperature and exergy can be easily interpreted as the thermodynamic quality part of an energy stream As explained in this section exergy can easily be calculated as any other thermodynamic property once the properties of the surrounding environment are defined Note that exergy is a definition of thermodynamic availability and equivalence and is not a definition of technical usefulness As an example if natural gas is needed for a given process the same amount of exergy with say steam or coal does not satisfy the needs and could not be used alternatively Lack of interpretation is in many cases the real cause of the not so widely used exergy analyses Energy analysts should be quite knowledgeable about thermodynamics

1332 Exergy balance for an open system The exergy rate balance for a control volume is equal to

ndestructioExergyofRate

transferexergyofRate

eee

iiicvj

j j

changeexergyofRate

cv Iememdt

dVcvpWQTT

dtdE

0

01 minusminus+

minusminus

minus= sumsumsum

4444444444 34444444444 21

(W) Equation 126

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 11

For steady-flow systems the balance obtained is

010 IememWQ

TT

ee

eiii

cvjj j

minusminus+minus

minus= sumsumsum (W) Equation 127

1333 Calculation of flow exergy changes The specific exergy change can be evaluated using following equation

)(2

)()( 21

22

21

2102121 zzgCCssThhee minus+minus

+minusminusminus=minus (Jkg) Equation 128

The values of enthalpy and entropy can be obtained either through property tables or with equations in Sections 123 124 and 131

1334 Second law efficiency exergetic efficiency The thermal efficiency and coefficient of performance defined in Section 1314 are based only on the first law of thermodynamics and make no reference to the best possible performance However the exergetic efficiency or second law efficiency overcomes this deficiency and gives a measure of approximation to reversible operation Exergetic efficiencies are useful for distinguishing means for utilising energy resources that are thermodynamically effective from those that are less so They can be used to evaluate the effectiveness of engineering measures taken to improve the performance of a thermal system The exergetic efficiency is defined in a generic form as the ratio between the exergy recovered and the exergy supplied

E recovered ε= E supplied (-) Equation 129

Exergetic efficiency expressions can take many different forms depending on the analysed system For a heat engine the exergy supplied is the decrease in the exergy of the heat transferred to the engine which is the difference between the exergy of the heat supplied and the exergy of the heat rejected The net work output is the recovered exergy For a refrigerator or heat pump the exergy supplied is the work input and the recovered exergy is the exergy of the heat transferred to the high temperature medium for a heat pump and the exergy of the heat transferred from the low temperature medium for a refrigerator More in general exergy producing systems and exergy dissipating ones can be distinguished The objective of the former is to transfer the exergy of the fuels to the products as much as possible thereby minimising both exergy losses and exergy destructions Most of the energy systems fall within this classification such as turbines compressors pumps boilers and most of the engines On the contrary devices exist whose objective is to dissipate a given flow with the less possible exergy input These devices are for instance draft fans for stack gases dryers or lamps among others From the second law point of view the objective of both types of devices is to dissipate as little exergy as possible The second law efficiency of the first devices is never greater than one On the contrary the second law efficiency of the latter devices needs to be as much greater than one as possible In any case both the numerator namely the product or objective and the denominator namely the expended fuel should be expressed in exergy units

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14 Property diagrams tables databanks and computer programs

In the general literature diagrams tables databanks and computer programs exists on thermodynamic properties of substances

141 Pressure-temperature diagram The p-T diagram also called the phase diagram (Figure 11) shows the three phases of a pure substance separated by a line In each of the single-phase regions (solid liquid and gas) the phase of the substance is fixed by the temperature and pressure conditions The lines between one-phase regions are called two-phase regions and represent the conditions where two phases exist in equilibrium In these areas pressure and temperature are not independent and only one intensive property is required to fix the state of the substance The sublimation line separates the solid and vapour regions the vaporisation line separates the liquid and vapour regions and the melting or fusion line separates the solid and liquid regions A substance being to the left of the vaporisation line is said to be at the state of a sub-cooled or compressed liquid if it is found at the right of the same line the substance is in a superheated vapour state All three lines meet at the triple point where all the phases coexist simultaneously in equilibrium In this case there are no independent intensive properties there is only one pressure and one temperature for a substance in its triple state The so called critical point can be found at the end of the vaporisation line At pressures and temperatures above the critical point the substance is said to be at a supercritical state where no clear distinction can be made between liquid and vapour phases

Substances thatexpand on

freezingSubstances that contract

on freezing

Critical pointS L

LV

Triple point

SV

SOLID

SOLID

P

T

Figure 11 Pressure-temperature diagram

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142 Pressure-specific volume and temperature-specific volume diagrams

Figure 12 and Figure 13 show a pressure-specific volume (P-v) and a temperature-specific volume (T-v) diagram respectively The two-phased region labelled liquid-vapour in both diagrams is commonly called the wet or the dome region The state at the top of that region is again the critical point Inside the dome a substance is a mixture of saturated liquid and saturated vapour The area under a given curve on the P-v diagram representing a quasi equilibrium process is

expressed as dvp

v

vint2

1 which is according to Equation 119 the specific boundary work Therefore P-v diagrams are very useful in the analysis of processes involving boundary work The isotherm lines (states with equal temperature) appearing on the P-v diagram indicate that inside the dome the pressure remains constant at a fixed temperature However in the single-phase liquid and vapour regions the pressure decreases as the specific volume increases Similarly the isobars (states with equal pressure) shown on the T-v diagram indicate that inside the dome the temperature remains constant at a fixed pressure but in the single-phase regions the temperature increases with the specific volume

P

f g

Vapour

TgtTC

Liquid-vapour

Liquid

TltTC

Criticalpoint

TC

VTC = critical temperaturef = saturated liquidg = saturated gas

Figure 12 P-v diagram

Chapter 1

14 Version April 2006 SSEIPPCBENE_Draft_1

V

T

f g

VapourLiquid

Liquid-vapour

PltPC

PgtPC

PC

Criticalpoint

PC = critical pressuref = saturated liquidg = saturated gas

Figure 13 T-v diagram

143 Temperature-entropy diagram Temperature entropy (T-s) diagrams are widely used in thermodynamics because they are very useful in visualising irreversibilities of processes Constant volume constant pressure and constant enthalpy lines can be seen in T-s diagrams The slope of constant volume lines in single-phase regions are always steeper than those of constant pressure lines For superheated vapour states the constant enthalpy lines become almost horizontal as pressure is reduced The pressure change between states in this region can be neglected therefore entropy is the only function when temperature and gases behave more like ideal gases

Since the internally reversible heat transfer is expressed as int=

2

1int TdSQrev (see Equation 16)

the area under the curve on a T-s diagram represents revQint

Vertical lines on T-s diagrams represent processes undergoing isentropic (same entropy) compressionexpansion while horizontal lines inside the dome mean isothermal phase changes (vaporisationcondensation)

s

T

Vapour

p=constv=const

h=constp=const

v=const

Liquid-vapour

Criticalpoint

Liquid

Figure 14 Temperature-entropy diagram

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SSEIPPCBENE_Draft_1 Version April 2006 15

144 Enthalpy-entropy diagram By means of an enthalpy-entropy diagram (h-s) commonly called Mollier diagram (see Figure 15) the two major properties of interest in the first and second law analysis of open systems are represented The change in enthalpy ∆h corresponds to a vertical line in the h-s diagram and is related to the work changes for turbines compressors etc in adiabatic steady-flow processes The change in entropy ∆s is represented in the diagram by a horizontal line and gives an idea of the irreversibility for an adiabatic process On an h-s diagram constant pressure and constant temperature lines are straight in the dome region In the superheated region constant temperature lines become horizontal meaning that enthalpy and temperature are directly proportional This is the region where the ideal gas model can be reasonably applied

s

h

Liquid Liquid-vapour

Criticalpoint

Vapour

p=const

p=const

T=const

T=const

x=quality

Figure 15 Enthalpy-entropy diagram

145 Property tables databanks and simulation programs For many substances associated with industrial processes properties can be presented in the form of tables They come from experimental data The most frequently listed properties in tables are specific volume internal energy specific enthalpy specific entropy and specific heat Property tables can be found in thermodynamic books and there is also an example in Annex 1 Due to the fact that in one-phase regions two intensive properties must be known to fix the state for superheated vapour and compressed liquid the properties v u h and s are listed versus temperature for selected pressures If there are no available data for a compressed liquid a reasonable approximation is to treat compressed liquid as saturated liquid at the given temperature This is because the compressed liquid properties depend on temperature more strongly than they do on pressure The so called saturation tables are used for saturated liquid and saturated vapour states Since in two-phase regions pressure and temperature are not independent one of the properties is enough to fix the state Therefore in saturation tables the properties v u h and s for saturated liquid and saturated vapour are listed either versus temperature or pressure In the case of a saturated liquid-vapour mixture an additional property called quality (x) must be defined Quality is defined as the vapour mass fraction in a saturated liquid-vapour mixture

(-) Equation 130

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16 Version April 2006 SSEIPPCBENE_Draft_1

Where mg represents the mass of saturated vapour and mf the mass of saturated liquid The properties of such a mixture are determined by the aid of the saturated tables and the calculated quality is as follows yav = yf+xyfg Equation 131 Where bull y calculated quality bull v specific volume bull u internal energy per unit of mass bull x quality bull yfg mixture of quality (gas and liquid) yfg = yg - yf Equation 132 Tables in the real world are not enough There is a strong need to have thermodynamic properties of many substances both pure and mixed In fact complex thermodynamic data banks and associated physical property models form the heart of any computer energy simulator The need is so important that inaccuracy or unavailable data may lead to the rejection of attractive energy conservation solutions Fortunately a considerable amount of databases and computer programs may be found in thermodynamic literature and on the market A problem arises in having the knowledge to select data with good criteria even if contradictory data are found Quality accurate and up-to-date information is in many cases critical This is a key issue when calculating mixture properties in which departure from non-ideal behaviour is common Some major data compilations can be found from the following sources bull the American Petroleum Institute API bull Beilstein Institute of Organic Chemistry BEILSTEIN bull Design Institute for Physical Property Data DIPPR of AIChE bull Deutsche Gesellshaft fuumlr Chemisches Apparatewesen Chemische Technik und

Biotechnologie eV DECHEMA bull Physical Property Data Service PPDS in the UK For instance DIPPR has a comprehensive pure component data compilation meanwhile a primary source of mixture data is DECHEMA Commercial simulation programs with extensive capabilities for calculating thermodynamic properties can be easily found Three of the most experienced programs are the trademarked ASPEN PLUS HYSIM and PROII However these computer packages may do more than what a common energy saving analyst needs to do or perhaps they perform in a less specialised way On the other side these programs are costly both in effort of handling and money for acquiring and maintaining Intermediate solutions that allow the analyst to compose their own simulating solutions and include pure substance properties are for instance EES Thermoptim and BBlocks Therefore the analyst must devote time in judging which is worth buying Starting from scratch is not very advisable in most cases

15 Identification of inefficiencies Mechanical thermal and chemical equilibrium conditions of a thermodynamic system also imply three causes of disequilibrium or inefficiencies (irreversibilities in thermodynamics) Mechanical irreversibilities are due to pressure changes and always appear in processes that involve friction Entropy generation and exergy destruction are always associated with mechanical irreversibilities the greater the pressure change the greater the irreversibility created within the system

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Thermal irreversibilities appear when there is a finite temperature change within the system as for instance in every heat exchanger The heat passes from a warm body to a cold one spontaneously thereby losing exergy Again the irreversibility produced increases with the temperature change Chemical irreversibilities are due to a chemical disequilibrium occurring in mixtures solutions and chemical reactions For example when water and salt are mixed exergy is destroyed This exergy loss is equivalent to the minimum work that has been previously needed to purify water in order to obtain the salt All atmospheric and water pollution effects are included here It is very easy to contaminate (mix) but a lot of exergy is needed to clean up The thermodynamic analysis of irreversible processes reveals that in order to obtain a good efficiency and save energy it is required to control and minimise all the mechanical thermal and chemical irreversibilities appearing in the plant Three case studies now follow throttling devices (see Section 151) focusing in mechanical irreversibilities heat exchanges (see Section 152) focussing on thermal irreversibilities and mixing processes (see Section 153) focussing on thermal irreversibilities and have been developed in order to illustrate the ideas and calculation methodologies for identifying and minimising irreversibilities

151 Case 1 Throttling devices Throttling devices are very common in industry and are used to control and reduce pressure mainly through valves Since the throttling process is isenthalpic (where the enthalpy up and down flows are equal) no energy is lost and according to the first law of thermodynamics its efficiency is optimal However this is a typical mechanical irreversibility which reduces pressure and increases the entropy of the fluid without giving any additional benefit Consequently exergy is lost and the fluid is less capable of producing energy in a turbine expansion process for instance Therefore if the point is to reduce the pressure of a fluid it is desirable to tend to isentropic expansions providing useful work as an additional result through turbines If this is not possible the working pressure should always be the highest possible because this will avoid the use of compressors or pumps for fluid transportation (additional useful energy) A very frequent practice in industrial installations is to keep the pressure at the inlet of the turbine at the design conditions This usually implies the use and abuse of admission valves to control the turbine According to the second law it is better to have flotation of the pressure specifications (sliding pressure) and to keep the admission valves completely open As a general recommendation valves should be sized as large as possible A satisfactory throttling process can be achieved with a pressure drop of 5 - 10 at maximum flow instead of 25 ndash 50 as it happened in the past where valves were small sized Of course the pump driving the fluid must be also sized according to the variable conditions Finally it must be stressed that pipes also act as throttling devices decreasing the pressure of the fluid flowing through them Therefore a good design with good materials and few obstacles such as unnecessary valves elbows bows etc will limit the exergy losses across the process In any case it is clear that an exergy accounting that considers all the energy levels existing in the plant must be performed because from the first law point of view irreversibilities are very difficult or impossible to identify

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18 Version April 2006 SSEIPPCBENE_Draft_1

Numerical example During a unit commissioning in a power plant a steam extraction coming from the high pressure turbine (P = 40 kgcm2 T = 350 ordmC) is used in order to feed a turbopump Since the turbopump operates at an inlet pressure of 8 kgcm2 the steam coming from the high pressure turbine must be throttled (see Figure 16) In the following thermodynamic example variables of the steam are evaluated at the inlet and outlet of the valve The process is sketched on the T-s and h-s diagrams (see Figure 17) and the exergy flow is obtained when the nominal flow is 45000 kgh

1 2

P1= 40 kgcm2

T1= 350 degCP2= 8 kgcm2

Figure 16 Steam throttling process

Solution The first law of thermodynamics reveals that the process is isenthalpic since no work or heat transfer is associated with the throttling process 0 = m1(h2-h1) gt h2 = h1 Equation 133 The specific enthalpy and entropy obtained through the property tables are bull At P1 and T1

o h1 = 309195 kJkg and s1 = 658 kJkg K bull At P2 and h2 = h1

o T2 = 319 ordmC o S2 = 730 kJkg K

S

T

T1

T2

s2s1

1

2

h = 309195 kJkg

h

1 2

Ss2s1

h1 = h2

Figure 17 T-s and h-s diagrams for the steam throttling process of the example

The specific flow exergy is calculated as e = h ndash T0s Equation 134

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SSEIPPCBENE_Draft_1 Version April 2006 19

Where T0 = 273 K and the potential and kinetic energy are considered negligible Hence e1 = 309195 ndash 273 x 658 = 129561 kJkg and e2 = 309195 ndash 273 x 730 = 109905 kJkg This process is completely irreversible (mechanical irreversibility) The exergy loss is obtained through an exergy balance to the system Since there is no heat or work transfer the exergy balance reduces to

152 Case 2 Heat exchangers Heat exchangers are devices where two streams exchange heat Every heat transfer is the result of a temperature difference and thus is always associated with entropy generation and exergy destruction Therefore there is a contradiction between the ideas of minimum exergy loss and maximum heat transfer efficiency (see Section 461) In a counterflow heat exchanger like the one shown in Figure 18 where a hot fluid at T1in is cooled down to T1out by releasing heat to a cold fluid that heats up from T2in to T2out therefore the exergy loss in the process is calculated as follows The change in kinetic and potential energy are usually negligible and no work interactions are present For a first approximation the pressure drop can also be considered negligible The irreversibility created in the heat exchanger is given by I = (e1in + e2in) ndash (e1out + e2out) = (h1in + h2in) ndash (h1out + h2out)

T1out T2out - T [(s1in + s2in) ndash (s1out + s2out)] = T0 [ m1Cp1ln T1in

+m2Cp2 ln T2in Equation 135

It can be demonstrated from the equation above that I is always positive and increases with the temperature differences at the inlet and outlet of the fluids in the counterflow exchanger and between the top and bottom in a parallel-flow one In any case a counterflow exchanger is always better than a concurrent one (parallel-flow) from the exergy point of view because exergy is always being giving off to a system at a similar temperature The irreversibilities taking place in heat exchangers are due to two factors heat transfer caused by the temperature difference and pressure loss associated with the fluid circulation Both fluid friction and irreversible heat transfer can be reduced decreasing the fluid flow However in order to obtain the same effect of heat exchange a larger transfer area is required ie larger heat exchangers must be designed The idea of extending the use of counterflow heat exchange to the whole installation ie extending it to all flows to be heated or cooled in the plant so that the temperature change through which heat must flow is reasonably low leads to the energy integration of processes and the use of energy cascades This is the philosophy of the pinch methodology developed for the integration of heat exchanger networks The integration can also be extended to power cycles heat pumps and refrigeration cycles in the most efficient way In summary this procedure assures the lowest steam consumption (or any another heat source) and the lowest cooling water (or any other cold source) under the thermodynamic and technical conditions that may be assessed

Chapter 1

20 Version April 2006 SSEIPPCBENE_Draft_1

Fluid T1in

Fluid T2in

Fluid T1out

Fluid T2out

Figure 18 Counterflow heat exchanger

Numerical example In a boiler reheater (see Figure 19) 1100000 kgh of steam is heated from 350 to 540 ordmC at a pressure of 40 kgcm2 The heat absorbed by the steam comes from the exhaust gases of a combustion process The average temperature where the heat transfer occurs is 1000 ordmC In Figure 110 the process is sketched on the T-s and h-s diagrams and the heat absorbed by the steam and exergy losses is determined

P1 = 40 kgcm2

T1 = 350 degC

Q

P2 = 40 kgcm2

T2 = 540 degC

Figure 19 Reheating process of a steam flow

Solution The energy balance of the system considered in Figure 19 is m (h2 ndash h1) = Q Equation 136 The specific enthalpy and entropy obtained through the property tables is bull At P1 and T1

o h1 = 309195 kJkg and o s1 = 658 kJkg K

bull At P2 and T2

o h2 = 353085 kJkg and o s2 = 721 kJkg K

Hence the heat transfer obtained is Q = 11100000 x (353085 ndash 309195) = 4389 kJkg = 4827 x 106 kJh T-s and h-s diagrams are shown in Figure 110

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 21

S

T

S1

1

2

S2

P = 40 kgcm2

h

12

SS1 S2

P = 40 kgcm2h1

h2

Figure 110 T-s and h-s diagram for the steam reheating process of the example

The specific flow exergy is calculated as e= h ndash T0s Equation 137 Where T0 = 273 K and the potential and kinetic energy are considered negligible Hence e1 = 309195 ndash 273 x 658 = 129561 kJkg and e2 = 353085 ndash 273 x 721 = 156252 kJkg The exergy loss generated is given by

153 Case 3 Mixing processes The mixing of fluids with different compositions or temperatures is another process very common in industry This concept includes tempering processes for temperature control mixing processes for quality control substance purifying processes distillation etc For example an adiabatic mixture of two different ideal gases flows at the same temperature and pressure and n1 and n2 equals the number of moles of each flow The generation of entropy in the mixing process corresponds to the sum of the entropy increase of each gas due to their expansions from P to their new partial pressure of the mixture Hence

summinus=

minus

+= ii xxR

PP

RnPP

Rnnn

lnlnln1 22

1

1

2

1

σ (JK) Equation 138

Chapter 1

22 Version April 2006 SSEIPPCBENE_Draft_1

Since Pi = xiPi and sum=

i

ii

n

nx

the exergy loss is calculated as follows I = T0σ = - RT0sum xi ln xi (J) Equation 139 This expression is always positive and symmetrical with respect to the value xi = 05 It tends to zero when xi tends to zero (maximum purity) Figure 111 shows IiRT0 versus the molar fraction of one component in the mixture xi The maximum exergy is reached when xi = 0 butunder these conditions it is relatively easy to separate both components As the mixture is being purified the exergy loss per mol of the separated component increases

08

Mole fraction of one component x

02 100806040

02

04

06

Ixiln xi

x

R=minusΣ

xilnximinus

Figure 111 IiRT0 versus molar fraction of one component in the mixture

For the considered binary system the irreversibility is equal to

[ ])1ln()1(ln0 xxxxRTI minusminus+minus= and

minus

minus=)1(

ln0 xxRT

dxdI

Equation 140 Some of the values of this derivative are presented in Table 11

x IRT0 (1RT0) dIdx 010 0325 220 001 0056 496

10 - 3 791 x 10 - 3 691 10 - 4 102 x 10 - 3 921

Table 11 Some values of the derivatives

Chapter 1

SSEIPPCBENE_Draft_1 Version April 2006 23

This derivative indicates the work required to improve the purity of the product and the easiness to pollute In other words the exergy value of the product is related with this derivative Multicomponent mixtures behave in the same way The maximum value of the function -sum xi ln xi that takes place for equimolar mixtures is shown in Table 12

N - sumxilnxi N - sumxilnxi2 0693 5 1609 3 1099 7 1946 4 1386 10 2302

Table 12 Maximum values for mistures

As the number of components of the mixture increases the irreversibility effects become more dramatic These ideas lead to a set of recommendations for energy saving in mixing processes Firstly and most importantly mixing processes must be avoided whenever it is possible Obtaining high quality steam or a very pure substance requires a great amount of exergy that is mostly lost when mixed with a lower quality flow (even if the energy loss is zero) Secondly the quality specifications of a certain product must not be exceeded and above all once they are exceeded they should never be mixed with lower quality flows This way if a product with 01 purity is mixed equimolarly with another of 1 purity the final product will have 055 purity but the exergy value of this product will decrease

significantly with respect to the individual flows since this is related with the derivative dxdI

and not with the mean composition value Some quality specifications of products should be reviewed and should be made lsquosofterrsquo if possible This is something basic in the chemical industry in which it is very common to find partially refined matter mixed with over purified products or mixtures of products coming from two parallel units for achieving an average purity Numerical example A steam flow at a pressure of 180 kgcm2 and a temperature of 550ordmC is mixed with saturated liquid at 180 kgcm2 in order to reach the temperature design specifications of a certain equipment (see Figure 112) In Figure 113 the final temperature of the mixture and the exergy loss is determined when the mass flow of steam is 1100000 kgh and of the liquid 30000 kgh

Hot stream (1)

Cold stream (2)Mixed stream (3)

P3 = 180 kgcm2

P1 = 180 kgcm2 T1 = 550 degC x = 0

P2 = 180 kgcm2 x = 0

Figure 112 Mixing chamber of two flows

Chapter 1

24 Version April 2006 SSEIPPCBENE_Draft_1

Solution The mass balance of the system is m1 + m2 = m3 Equation 141 Since there is no work or heat transfer to the process and the kinetic and potential energy can be assumed to be zero the energy balance reduces to m1 h1 + m2 h2 = (m2 + m1) h3 Equation 142 At P1 and T1 the specific enthalpy and entropy obtained through the property tables is h1 = 34142 kJkg and s1 = 641 kJkg K respectively For the saturated liquid at the cold stream (2) only one property (pressure in this case) is needed to fix the state h2 = 171706 kJkg and s2 = 385 kJkg K From the energy balance applied above

At the mixed stream (3) with h3 and P3 T3 = 534 ordmC and s3 = 635 kJkg K The change in specific enthalpy and entropy can be obtained with the help of the property tables in Annex 1 The specific flow exergy is calculated as Equation 137 where T0 = 273 K and the potential and kinetic energy are considered negligible Hence e1 = 166452 kJkg e2 = 66667 kJkg and e3 = 163455 kJkg The irreversibility is obtained through the exergy balance I = m1(e1 - e3) + m2 (e2 ndash e3) =gt I = 11 x 106(166452 ndash 163455) + 30 x 103(66667 ndash 163455) = 376 x 106 kJh = 104 MW The T-s diagram is shown in Figure 113

S

T

T1

T3

T2

S2 S3 S1

P = 180 kgcm2

1

2

3

Figure 113 T-s diagram for the mixing process of the example

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SSEIPPCBENE_Draft_1 Version April 2006 25

Remarks for all three case studies Irreversibilities are the effects of any improvable energy system Besides avoiding finite pressure temperature andor chemical potential differences the causes of poor energy design come from decoupling supply and demand Time plays an important role in energy efficient systems Energy systems spontaneously decrease its pressure temperature and chemical potential to reach equilibrium with its surroundings To avoid this there are two strategies bull to couple energy donors with energy acceptors immediately bull storage to enclose a system within rigid walls for pressure adiabatic walls for temperature

andor to confine the chemical systems into metastable states In other words confine the systems into reservoirs that maintain their intensive properties constant with time

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 27

2 ENERGY EFFICIENCY [4 Cefic 2005] [5 Hardell and Fors 2005] This chapter deals with definitions of energy efficiency relevant for industry and how to develop indicators to monitor energy efficiency Furthermore it deals with different aspects which influence energy efficiency some of which a company has control over and some of them not It also gives examples on how different system boundaries influence energy efficiency

21 Definitions of energy efficiency Defining energy efficiency is a complex task It is not possible to present a solution that will fit in all cases and will satisfy all stakeholders When the term energy efficiency is used the meaning of the term is usually not defined When it is defined the meaning depends on the context in which it is used The main reason is that everyone does not deal with energy in the same way or use the same system boundary It may be simple to describe the meaning of energy efficiency for a single component or a subsystem whereas some difficulties arise as soon as it comes to definitions of energy efficiency for complex industrial plants Because energy efficiency means different things for different stakeholders clarification on what energy efficiency means in this document is required First a distinction needs to be made between energy efficiency at the macro level (eg national) and at the micro level (eg company level) In this document only the latter is discussed (see Scope) Furthermore the main focus of this document is on physical energy efficiency although economic efficiency will be touched on as well In this document energy efficiency is dealt with from an industrial perspective within the installation boundaries without considering a productrsquos life cycle This is in line with the IPPC Directive which deals with production and not with products The fuel by which energy is produced is also not considered in this document There is not a commonly agreed definition of energy efficiency in the EU The IPPC Directive does not define energy efficiency either However it requires IPPC installations to be driven energy efficiently and energy efficiency is part of the BAT consideration and should be addressed in permit application and permit conditions Thus to fulfil the requirements of demonstrating energy efficiency good indicators are needed Energy efficiency has been defined eg in the following ways bull a ratio between an output of performance service goods and energy and an input of

energy A definition can be found in the Common Position No 342005 on Energy and Use Efficiency and Energy Service Directive (9376EEC) where energy efficiency is defined According to this definition the replacement of other fuels by renewables does not improve energy efficiency Also energy efficiency improvement is defined in the same Common Position as an increase in energy end-use efficiency as a result of technological behavioural andor economic changes These definitions have a broader scope than just energy efficiency in industry

bull to obtain an unchanged output value at a reduced energy consumption level (the Swedish Energy Agency)

bull to obtain an increased output value with unchanged energy consumption or to obtain an output value that in relative terms surpasses the increase in energy consumption (the Swedish Energy Agency)

bull the amount of energy consumed per unit of productoutput bull the amount of energy consumed per unit of feedstock

Chapter 2

28 Version April 2006 SSEIPPCBENE_Draft_1

bull energy consumption per unit of product where the consumption of energy is from energy carriers This does not refer to non-energy consumption in the form of feedstocks The energy consumption from secondary energy carriers will be allocated back to the net caloric value (lowest combustion value) of the primary energy carriers Net electricity purchases will be offset at a generation yield requiring the approval of the independent authority When this is used the determination of the proportion of feedstock in energy consumption for each relevant processing plant typically requires the approval of the independent authority [13 Dijkstra ]

In industry the most commonly used definition for energy efficiency is the amount of energy consumed per unit of productoutput which can also be called specific energy consumption or energy intensity factor Improving energy efficiency therefore means reducing the amount of energy required to produce a unit of product This definition will mainly be used in this document The definition looks deceptively simple However once one tries to quantify the concept for monitoring processes experience shows that a framework is required to better define and measure energy efficiency This framework is provided in Section 22 The definition as such does say much about the issue of whether energy is used or produced efficiently To be informative and useful energy efficiency must be compared to something (another unit company over time) and for comparison there must be rules In the case of comparing energy efficiency it is especially important to define system boundaries so that all users are speaking equally As it simplest the definition neither takes a view on how efficiently energy is produced nor how lsquowastersquo energy is used after the system boundary Eg these issues and several others must be decided transparently so that it is possible to evaluate improvements of energy efficiency All these issues will be dealt with in Section 23 Energy efficiency is considered mainly from the perspective of a single industrial company and from the perspective of a production site grouping several production processesunits However the best energy efficiency for a site is not always equal to the sum of the optimum of the energy efficiency of the contained production processesunitscomponents De-optimisation of the energy efficiency of one or more production processesunits may be required to achieve the optimum energy efficiency of the site That is why it is crucial to understand how the definition of a system boundary will influence energy efficiency Furthermore by extending system boundaries outside a companyrsquos activities and by integrating industrial energy production and consumption with the needs of community outside the site the total energy efficiency could be increased eg by providing low value energy for heating purposes in the neighbourhood

22 Energy efficiency indicators in industry Definitions used for energy efficiency were discussed in Section 21 This section express how energy efficiency and indicators are developed for individual industrial production processesunitssites It explains what and how to consider the relevant issues The main target of the indicators is to make a self analysis possible or to compare units to other units or to other companies The importance of clear decisions of system boundaries energy vectors (energy flows) and the way to deal with other related issues (eg wastefuel electricity conversion factor) is expressed

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 29

221 Production processes A production processunit is a process which takes in one or more feeds and converts these into one or more valuable products and in doing so consumes energy Examples of production processesunitssites are bull a gas powered electricity plant takes in gas as its feedstock and the product of this

production process is electricity The energy used is the energy available within the gas Electricity can be also produced in a combined heat and power plant and then the total efficiency is of course better

bull a refinery takes in crude oil and transforms this into gasoline diesel fuel oil and a number of other products A part of these products is burned internally to provide the necessary energy for the conversion process Usually some electricity also needs to be imported unless a cogeneration plant is installed within the refinery in which case the refinery may become a net exporter of electricity

bull a steam cracker takes in liquid and gaseous feeds from a refinery and converts these to ethylene and propylene plus a number of by-products Part of the energy consumed is generated internally in the process supplemented by imports of steam electricity and fuel

bull the feeding to the rolling mill in a steel works consists of approximately 2 decimetres thick flat steel plates that are to be rolled out to bands with a thickness of a few millimetres The rolling mill consists of furnaces rolling mill equipment cooling equipment and support systems including pumps fans hydraulics and lubricating systems lights a mechanical workshop staff space changing rooms etc See Section 244

After defining energy efficiency indicators it will be possible to measure and evaluate the changes in efficiency eg demonstrate that energy is usedproduced efficiently

222 Energy intensity factor and energy efficiency index To show how energy efficiency is developed over time in a company or to make benchmarks between different companies the following indicators may be used the energy intensity factor and the energy efficiency index The energy intensity factor is often called the specific energy consumption and it expresses the amount of energy used to produce the given product(s) How to develop the structure to define energy efficiency and indicators for production units and sites will be expressed in Sections 223 and 224 The main purpose of the energy efficiency indicators is to be able to monitor the progress of the energy efficiency of a given production unit over time and to see the impact of energy efficiency improvement measures and projects on the energy performance of the production processunit In its simplest form the energy intensity factor (EIF) can be defined as EIF = (energy imported ndash energy exported)products produced Equation 21 EIF is a number with dimensions eg GJtonne The energy efficiency index (EEI) is defined by dividing a reference energy intensity factor by the energy intensity factor EEI = EIFrefEIF Equation 22 EIFref can either be a reference number which is generally accepted by the industry sector to which the production process belongs or it can be the energy intensity factor of the production process at a given reference year

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The energy efficiency index is a dimensionless number and can be used to for instance measure the progress on energy efficiency of the given process over time EIF is a number that decreases with increasing energy efficiency whereas EEI is a number that increases Energy management therefore targets the lowest possible EIF and the highest possible EEI EIF shows how much energy is used to produce given products but without any reference to previous achievements That is why the value of one single figure alone is not very big EEI shows the trend and is more useful For monitoring purposes the time frame on which the energy efficiency is calculated is best taken for long periods (eg months or years) For example on an hourly basis the energy efficiency indicator may show large fluctuations for a continuous process and it would actually not even make sense for a batch process These fluctuations are smoothed out on longer period basis While Equation 21 and Equation 22 look deceptively simple experience shows that the definitions leave room for interpretation and issues like system boundaries energy vectors and how to deal with different fuels must be defined and decided before use them especially when comparing one production process with another In addition to the two main indicators dealt with here there are also other indicators and sub-indicators One example of a sub-indicator is a pressure level in a compressing system which clearly indicates energy efficiency

223 Energy efficiency in production units In the following two examples the concepts of EIF and EEI are illustrated Example 1 Simple case Figure 21 shows an example of a simple production unit For transparency reasons the handled process will be without energy exports and with only one feedstock and one product The production process makes use of steam electricity and fuel

SteamEsin

Productionunit

Main product P

Fuelimport

Efin

ElectricityEein

Feed F

Figure 21 Energy vectors in a simple production unit

The EIF of this process is given by

Equation 23

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Where bull Esin energy supplied to the process via steam to produce an amount of product P bull Eein energy supplied to the process via electricity to produce an amount of product P bull Efin energy supplied to the process via fuel to produce an amount of product P In Equation 23 it is essential that the various energy vectors (energy flows) are expressed as primary energy and on the same footing For instance 1 MWh of electricity requires more energy to produce than 1 MWh of steam as electricity is typically generated with an efficiency of 35 ndash 55 and steam with an efficiency of 85 - 95 The energy use of the different energy vectors in Equation 23 therefore needs to be expressed in primary energy This includes the efficiency to produce that energy vector (see also Section 232) An example of a calculation of energy efficiencyAssume that to produce 1 tonne of product P1 the following energy vectors have to be used bull 001 tonne of fuel bull 10 kWh of electricity bull 01 tonne of steam Now assume further the following bull lower calorific value of fuel = 50 GJtonne bull efficiency to produce electricity = 40 bull steam is generated from water at 25 degC bull the difference between the enthalpy of steam and the enthalpy of water at

25 degC = 28 GJtonne bull steam is generated with an efficiency of 85 To produce 1 tonne of product P1 the energy consumption is as follows bull Efin = 001 tonne fuel x 50 GJtonne = 050 GJ bull Eein = 10 kWh x 00036 GJkWh x 104 = 009 GJ bull Esin = 01 tonne steam x 28 GJtonne x 1085 = 033 GJ The EIF of this process is then given by bull EIF = (050 + 009 + 033) GJtonne = 092 GJtonne For the concept of EEI assume that this is the reference EIF Now assume that the plant carries out a number of energy efficiency improvement projects so that a year later the energy consumption of the production process has become bull 001 tonne of fuel bull 15 kWh of electricity bull 005 tonne of steam As a result of these energy efficiency improvement projects the new EIF of the process is bull EIF = (05 + 0135 + 0165) GJtonne = 08 The EEI of this process is then bull EEI = 09208 = 115 This indicates that the energy efficiency of the production process has increased by 15

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Example 2 More general case Figure 22 deals with a more general case when there is both export of energy and internal recycling of fuel The general case presented here is believed to be sufficiently flexible to be applicable for most industries

Production unit

Recycled fuel Efrec

Main products P1

Other products P2

ElectricityEeout

OtherEoout

Wastelosses W (incinerationflareeffluentto environment)

SteamEsout

Feed F1

Feed Fn

SteamEsin

ElectricityEein

OtherEoin

Fuel importEfin

Recycled fuel Pf

Figure 22 Energy vectors in a production unit

The energy intensity factor EIF of this process is then defined as follows

Equation 24

This generic formula can be applied to each production processunit or site but its various components have to be adapted to each specific production processunitsite The unit of this indicator is (unit of energy)(unit of mass) usually GJt product or MWht product Some consideration to take into account when applying Equation 24 (some also applicable to Equation 23) are described in the seven points follow

1 Feedproduct flows (Fi Pi)

In the horizontal direction the mass-flow of the products is shown in Figure 22 The feeds Fiare the different raw materials used to produce the product The products coming out of the process are split into main products P1 and by-products These by-products are split in two fractions a fraction which is recycled as fuel (Pf) and the remaining other products (P2) An example that can be derived from the petrochemical industry is the ethylene steam crackers where energy consumption can be expressed in GJ per tonne ethylene in GJ per tonne olefins (ethylene + propylene) or in GJ per tonne of high value chemicals (olefins + butadiene + benzene + pure hydrogen) This approach is also valid in the chlor-alkali field where consumptions are usually related to the tonne of Cl2

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2 Energy vectors flows (Ei)

Energy vectors are different types of energy flows going and going into the unit In the vertical direction of Figure 22 the energy imported and the energy exported which is used elsewhere are shown The following energy vectors are considered bull Es = steam andor hot water bull Ee = electricity to the process bull Ef = fuel (gas liquid solid) A split is made between the externally purchased fuel and the

fuel which is internally recycled in the process bull Eo = other this covers any utility which requires energy to be produced Examples are hot

oil and cooling water This cooling water requires energy to produce it (energy is required to operate the pumps circulating cooling water and the fans on the cooling towers)

It is important that on the export side only those energy vectors which are lsquousefullyrsquo used after a main processunit in another process are counted In particular the energy associated with cooling of the product to cooling water or air can never be included as the lsquoenergy outrsquo in Equation 24 Energy is consumed to produce cooling water (operation of pumps and fans) but this energy is not always included which is similar to compressed air and N2 Heat losses to the air should also never be counted

3 Different steam levels (Es)

The production plant could be using or producing more than one type of steam (different pressures andor temperatures) Each of these steam levels needs to be included in the term EsHot water if used (or produced and used by another production plant) should be included Each level of steam may have to produce its own efficiency factor

4 Waste flows (W) Each process will also generate an amount of waste products These waste products can be solids liquids or gaseous and may be bull disposed of to landfill (solids only) or by incineration bull be used as fuel (Pf) or bull recycled The relevance of this waste stream will be discussed in more detail in Section 232

5 Fuel or product or waste (E0 Pf)

In Figure 22 fuel is not shown as an exported energy vector The reason for this is that fuel is considered as a product rather than an energy carrier and that the fuel value which would be attributed to the fuel is already present in the feed going to the production unit This philosophy is standard within refineries and the chemical industry Other industries may apply different practices For instance in the chlor-alkali industry some operators count the H2 (a co-product of the Cl2 and NaOH produced) as an energy vector independent of whether this H2 is subsequently used as a chemical or as a fuel (only the H2 flared is not counted) It is therefore important to establish the rules for defining energy efficiency specific to a given industrial sector such as feeds products energy carriers imported and energy carriers exported

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6 Time frame The energy intensity factor can be calculated on any desired time frame (hour week month year) The preferred time basis to compare energy efficiency is however a month or a year as this will better capture and level recurring energy consuming disturbances in the process For instance a process may have low relative energy consumption during normal operation but may have frequent shutdowns and restarts related to fouling which consume significant amounts of energy the monthly or yearly energy intensity factor will better capture the effect of these recurring events which measure the energy efficiency of the process

7 Measured or estimated Equation 24 assumes that the different energy vectors to the production process are known However for a typical production process the different utility consumptions (eg cooling water nitrogen steam tracing steam to a turbine electricity) are not always measured Often only the major individual utility consumptions of the production process are measured in order to control the process (eg steam to a reboiler fuel to a furnace) The total energy consumption is then the sum of many individual contributors of which some are measured and some are lsquoestimatedrsquo Rules for estimation must be defined and documented in a transparent way

224 Energy efficiency of a site Complex production sites operate more than one production processunits To define energy efficiency of a whole site it has to be divided into smaller units which contain process units and utility units The energy vectors around a production site can be schematically represented as in Figure 23

Unit Unit

Unit Utilities

Energy imported

Products out

Energy exported

Feeds in

Figure 23 Inputs and outputs in a site

A production site may make different types of products each having its own energy intensity factor It is therefore not always easy to define a meaningful energy efficiency indicator for a site The indicator may be the following

Equation 25

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An issue which needs to be addressed when dividing the production sites into production units (see Section 232) is whether the utility centre should be seen as a separate production unit Usually this is the case as the utility centre produces utilities for more than one production unit The next issue is whether this utility centre will have its own energy consumption or whether it just converts one energy vector in another The utility section in itself may be divided in several sections for instance it could be divided in a part related to the storage and loadingunloading area a part related to hot utilities (steam) and a part related to cold utilities (cooling water N2 compressed air) The following equation should always be verified

sectionutility byusedEnergy PEIF site by the usedEnergy units i

i +lowast= sum=

iEquation 26

For implementation of energy management in the site it is essential to divide the site into its production units including the exact system boundary of these production units to clearly define the energy flows in and out of the site and between the different production units (Unit boxes in the Figure 23) This then clearly defines the way in which the energy efficiency of a given production process is calculated This break-up of a site into production units will depend on the complexity of the production site and has to be decided ndash in every single case ndash by the operator responsible

23 Issues to be considered when defining energy efficiency indicators

In Sections 223 and 224 it was discussed how to develop energy efficiency for a production unit and for a site Sections 231 and 232 discusses some important issues that can be decided by the company and which should be taken into account in the definition of energy efficiency and indicators Section 233 discusses structural issues that are not typically under the decision of a single company but influence the definition of energy efficiency

231 System boundaries

2311 Definition of the system boundary It is most important to clearly define the system boundaries of a processunit when defining the efficiency of a processunitsite (eg whether the boilers are included in the main process unit or whether they are independent) When this has been decided once the same decisions will always apply Steam boilersSteam boilers may be included as an individual unit or as a part of process unit For instance on small sites with only one production process on the site the steam boiler will often be included in the system boundary of the production process The primary energy source in this case will be the fuels burned on the steam boiler In contrast on large sites which often have common boilers for all processes the steam boiler will often be left out of the system boundary of the production process and the main energy carrier will be steam rather than fuel

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Auxiliary unitsAnother issue is when auxiliary units are included in the system boundary An example is the case of gasoline hydrotreaters in a steam cracker Gasoline is a co-product of a steam cracker (hence is counted in P2 rather than P1 in Figure 22) Before it can be added to the gasoline pool it needs however to be hydrotreated to saturate the olefins and diolefins present and to remove the sulphur components Most operators would treat the gasoline hydrotreater as a separate unit of the steam cracker However in some sites the gasoline hydrotreater is integrated to the cracker so that for simplicity purposes it is sometimes included within the cracker system boundary Not surprisingly those crackers which include the gasoline hydrotreater in their system boundary will tend to have higher energy consumptions than those which do not This of course does not imply that their energy efficiency is lower Components and sub-systemsIn Section 2312 there are several examples of how the definition of a system boundary influences the efficiency

2312 Examples of system boundaries In this section it will be illustrated how the efficiency changes when a system boundary is extended from a single component to a unit The section deals with single components subsystems or aggregate systems ie equipment types that are frequently to be found in the manufacturing and the process industries A number of examples have been chosen to illustrate the complications that may arise when trying to define the results of different measures for energy efficiency improvements Starting with the consideration of the efficiency of components and subsystems the further discussion takes into account what happens when a lot of subsystems are interconnected as is the case in industrial plants System 1 Old electric motorAn electric motor has been chosen as an example to show the differences in system boundaries In the company concerned an overview was made of existing motor drives and it was found that this motor was very old (see Figure 24) The electric power was 100 kW The efficiency of the motor was 90 and accordingly the mechanical output power was 90 kW

Old electric motor

System boundary

Electric power 100 kW

Mechanicalpower (90 kW)

Power input (100 kW) Output value (90 kW) Efficiency (90 )

Figure 24 System boundary ndash old electric motor

System 2 New electric motorTo improve the efficiency the motor was replaced by a high efficiency motor The effects of this change are shown in Figure 25

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New electric motor

(937 )

Electric power 96 kW

Mechanicalpower (90 kW)

System Boundary

Power input (96 kW) Output value (90 kW) Efficiency improvement (4 kW)Output unchanged

Figure 25 System boundary ndash new electric motor

The electric power needed to produce the same output power 90 kW is now 96 kW due to the higher efficiency of the new motor The energy efficiency improvement is thus 4 kW

System 3 New electric motor and old pumpAs shown in Figure 26 an electric motor is used to operate a pump that provides cooling water for a cooling system The combination of pump and drive is regarded here as one component The output value of this component is the hydraulic power in the form of cooling water flow and pressure Due to the low efficiency of the pump the output value is limited to 45 kW

New electric motor and old pump

(937 )

Electric power 96 kW

System boundary

Power input (96 kW) Output value (45 kW) Efficiency (47 )Output unchanged

Hydraulic power (45 kW)

Cooling water

(50 )

Figure 26 System boundary ndash electric motor + old pump

System 4 New electric motor and new pumpSix months after the replacement of the motor it was found to be necessary to replace the old pump by a new one thereby increasing the pump efficiency from 50 to about 80 The result of the replacement is shown in Figure 27

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38 Version April 2006 SSEIPPCBENE_Draft_1

New electric motor and new pump

(937 )

Electric power 90 kW

System boundary

Power input (90 kW) Output value (67 kW) Efficiency (75 )

Hydraulic power (67 kW)

(80)

Figure 27 System boundary ndash electric motor + new pump

The efficiency of the new equipment is evidently much higher than the previous one The hydraulic power has increased from 45 to 67 kW What improvement of energy efficiency has been attained if one Figure 26 and Figure 27 are compared A reduction of the input power by 6 kW Or an increase of the hydraulic power by 22 kW Or the sum of these changes ie 28 kW As was indicated in Figure 26 the cooling system worked properly even at a hydraulic power of 45 kW What is the benefit of an increase of the hydraulic power by 50 to 67 kW Does it mean that the pumping losses have now been transferred to a control valve and the piping system That was certainly not the intended aim of the replacement of components

System 5 New electric pump new pump and constant output valueAn unbiassed study of the cooling system might have shown that a hydraulic power of 45 kW was sufficient and in this case the shaft power can be estimated at 4508 = 56 kW The electric power needed to drive the motor would then be about 560937 = 60 kW See Figure 28

New electric motor and new pump with constant output value

(937 )

Electric power 60 kW

Power input (60 kW) Output value (45 kW) Efficiency (75 )

Hydraulic power (45 kW)

(80 )

Figure 28 Electric motor + new pump with constant output

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In this case the power input was 40 kW lower than before see Figure 24 The question is whether it could have been possible to reduce the size of both motor and pump without harmful effects on the cooling Or could it even be possible to reduce the required hydraulic power to eg 20 kW These types of questions are rarely brought up for discussion and even so no answers will generally be given Still in many cases asking good questions may be the starting-point for profitable improvements to energy efficiency

System 6 System 5 coupled with an heat exchangerIn Figure 29 the system boundary has been extended and the subsystem now includes a new motor a new pump and an old heat exchanger for the cooling process The process cooling power is 13000 kWth (th = thermal)

Hydraulicpower (67 kW)

New electric motor new pump and old heat exchanger

System boundaryCooling

water

(80)Heat from process

(13000 kWth)

Electric power 90 kW

Control valve

13000 kWth

Power input (90 kW) Output value 1 Process cooling 13000 kWth

Output value 2 Hydraulic power 67 kW

Figure 29 New electric motor new pump and old heat exchanger

The output value is represented by the removal of process heat and hydraulic power due to increased water flow and pressure How is the efficiency of the entire system to be defined And how will the efficiency be changed if the cooling needs decrease to 8000 kW caused by a reduction of the utilisation of production capacity

System 7 System 6 with recovery of heatDue to environmental concerns a decision was taken by the company to reduce the emissions of carbon and nitrogen dioxides by recovering heat from the cooling water thereby reducing the use of oil in the heating plant (see Figure 210)

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40 Version April 2006 SSEIPPCBENE_Draft_1

Electric power 90 kW

System boundary Coolingwater

(80)

Power input 90 kW

Control valve

Output value 1 Process cooling 8000 kWth

Heat from process 8000 kWth

Heat recovered replacing fuel oil for heating of premises 4000 kWth

Hydraulic power67 kW

unused heat4000 kWth

Output value 3 Hydraulic power 67 kWth

8000 kWth

Output value 2 Recovered heat 4000 kWth

Figure 210 New electric motor new pump and two heat exchangers

It is evident that the heat recovery arrangement represents an increased output value of the subsystem To estimate the value of the heat recovery in more detail the oil-fired heating plant needs to be considered as well The value of the reduction of the oil consumption the reduction of emissions and the decreasing heat recovery from hot flue-gases from the heating plant need to be taken into account In this case like in most others the subsystems are interconnected which means that the energy efficiency of one subsystem often has an influence on the efficiency of another

2313 Some remarks on system boundaries bull the importance of defining system boundaries is emphasised There are no general rules to

be applied but the lack of definitions can easily cause ambiguities in the understanding of what is included in a system

bull the more narrow the system boundary the easier will it be to state the energy consumption and the output value (See Figure 24 and Figure 25) In complex systems difficulties will often arise when trying to add up different energy savings

bull when the system boundaries are extended (see Figure 26 Figure 27 and Figure 28) to include a pump the output value will increase considerably when installing a new and modern pump The efficiency will increase from 47 to 75

bull in Figure 29 the system boundary has been further extended The major output value is represented by the cooling of process heat In comparison the produced hydraulic power is of minor importance

bull in Figure 210 the cooling power has been reduced considerably entailing reduced production The reason for this is a lower customer demand or changed market conditions Furthermore heat recovery has been introduced The input power to the motor is identical in Figure 29 and Figure 210 but in reality it would be lower in Figure 210 as the cooling demand has been reduced

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SSEIPPCBENE_Draft_1 Version April 2006 41

232 Other items to be decided by the company

1 Denominator in energy intensity factor and energy efficiency index In most cases it is quite clear that the denominator is the productoutput However sometimes it may be relevant to use the feedstock as a divisor and furthermore in cases when several products are produced over time it should be considered which is the most relevant denominator to achieve the best results bull products co-products and feedstock - in the simplest case the production unit will produce

one main product which can then be used as the divisor In some cases a number of equally important products or a number of important co-products can be produced Where appropriate the sum of these products can be used as the divisor Otherwise the boundaries have to be taken in order to have a meaningful consistence between the energy balance and the products balance

bull in some cases it may be more meaningful to use the amount of feedstock as the divisor This is often the case for mineral oil refineries where the number of product streams is high (eg typically 5 to 7 stream products for an atmospheric crude distillation) and constant and the number of feed streams is low (typically one stream) This divisor is recommended if the energy consumption of a given production unit is determined mainly by the amount of feedstock taken in and less by the amount of product coming out which could be the case when the latter quantity depends strongly on the quality of the feedstock However using feedstock as a divisor cannot take into accout a lost of efficiency of the process

bull several products in batch or in campaigns - special attention should be paid to sites making several different products either in batch or in campaigns As an example a polymer plant could make polymer grades A B and C These grades are made in campaigns for instance grade A may be produced for two weeks then grade B for four weeks and then grade C for one week before producing grade A again The market may determine the production quantities of these various grades and the relative fractions of these grades may vary from year to year Each grade may have its specific energy consumption for instance grade A may consume more energy per unit of product than grade B which itself consumes more energy than grade C To be able to monitor the energy efficiency indicator of the process it may be useful to define a reference energy efficiency indicator per grade (based on the average energy consumption for that given grade) The relevant energy efficiency indicator over a specific period could then be defined

period during produced Cand BAproducts ofSumconsidered periodover unit productionbyusedEnergy

irefCBAi

i EIFxEEI

lowast=

sum= Equation 27

Where xi is the fraction of grade i on total product produced over the given period and EIFrefi is the reference energy efficiency factor for grade i (calculated for instance by averaging the energy efficiency indicator over a reference period when only grade i was produced This is also applicable when the production plant produces only one product but with different specifications and each having a different energy usage

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42 Version April 2006 SSEIPPCBENE_Draft_1

2 Internal production and use of energy In several processes (eg refineries black liquor in pulp and paper plants) fuel that is produced in the process is consumed internally It is essential that the energy in this fuel is taken into account when looking at the energy efficiency of a process Indeed as shown in Section 222 refineries would have very low energy consumptions as all liquid and gaseous fuels (unless natural gas is used) consumed in the refining process are generated internally from the crude oil imported Typically 4 ndash 8 of the crude oil imported is converted into fuels which are consumed internally The only energy vector imported is then electricity (which is a small contribution compared to fuels burned) When the refinery is moreover equipped with a cogeneration facility it may be exporting electricity while increasing the internal fuel consumption According to the Equation 21 and Equation 22 a refinery equipped with a cogeneration facility would become a net energy producer Clearly this does not seem a good reflection of reality as common sense suggests that refineries consume significant amounts of energy Being aware of the above-mentioned issues it must be stated that system boundaries and energy vectors can be freely chosen but once defined for a specific plant these should be binding

3 Waste and flare recovery WasteAny process generates a quantity of solids liquid andor gaseous waste Often this waste will be recycled as a material or exported to an external incineration company Consider the case where the waste is sent to an external incinerator company Now assume that the production site finds a way to use this waste internally eg as fuel on its boilers or its furnaces Some reflection is required as to whether this improves the energy efficiency of the production unitsite bull the internal use of this waste reduces the need for external fuels but the overall energy

consumption still stays the same bull on the other hand the incinerator company may have an installation where the fuel value of

that waste is recovered via the production of steam In this case the rerouting of the waste stream for use as an internal fuel rather than sending it to an incinerator company may not result in any overall improvement of the energy efficiency when looking at the total picture of production company + incinerator company

In the proposed Equation 24 no credit is given for recovering waste as fuel However the switch from external incineration to internal use may be driven by commercial conditions Some industrial sectors may however have a different point of view and valorise the internal use of waste in their energy efficiency It is important that each industrial sector andor company clearly defines the standard practice applied

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SSEIPPCBENE_Draft_1 Version April 2006 43

FlareAny gas sent to flare is burned without recovery of any of the calories contained in the flare gas The reason is that the flare is really a safety device and well maintained operated and designed sites will have under normal operating conditions a small to negligible flow to flare Most sites will however have a constant small flow to the flare due to eg leaking relief valves and venting due to loadingunloading operations of storage tanks Some sites have therefore decided to install a flare gas recovery system which recovers this small flow and recycles it to the site fuel gas system Now suppose a production process which previously did not have a flare gas recovery system decides to install one This will reduce the external consumption of fuel gas whereas the overall fuel gas consumption of the process remains the same It is extremely important to define whether a credit for this fuel gas recovery system is allowed This is especially important if one production process recovers not only its own flare losses but also the losses to flare of other production processes on the site From the above considerations it should be clear that it is important to agree on the rules of how to deal with waste when setting up the framework to define the EIFEEI of a processunit One possibility is to define for a given process the reference practice on the amount of waste generated and to what extent it is recycled and to give an energy credit to those operators who are able to use the waste in a more efficient way than the reference case In any case it is essential that each industry defines clearly how to deal with wastes to allow a fair comparison between competing production processes

4 Primary energy conversion factor for electricity To be able to compare different forms of energy vectors it is necessary to define the concept of primary energy For electricity this is the quantity of energy required to produce one unit of electricity For instance current gas powered electricity stations based on combined cycle technology have an efficiency of approximately 55 to convert gas to electricity (defined as the amount of electricity out (in GJ)lower combustion value of gas going in) With CHP it is possible to reach 85 efficiency Different countries may use different conversion factors depending on the actual mix of plants used to produce electricity (eg hydropower combustion plants nuclear) Moreover this efficiency factor may increase over time as older plants are closed and more efficient plants are taken in operation Again it is important to clearly define which efficiency factor should be used Examples of defining the primary energy conversation factor bull when monitoring the energy efficiency improvement of a production process over time it

is important that in the definition of EIF and EEI the electricity conversion factor is kept constant If not it is not possible to separate the effect of an improvement in the energy efficiency of the process itself and the effect of the improvement of the energy efficiency of the electricity production in the country where the production process is located

bull however when reviewing the impact on the energy efficiency of a process when switching from one energy vector to electricity (eg changing from a steam turbine to an electric motor) it could make sense to use the actual electricity efficiency production factor of the country This allows the operator to look at what the best solution is for the combined total picture of the production process and the electricity production which may have another optimum than that of the production process alone

Chapter 2

44 Version April 2006 SSEIPPCBENE_Draft_1

5 Steam A definition which is often used for steam is the following (also see Section 43) Energetic value of steam = hs-hwnb Equation 28 Where bull hs enthalpy of steam bull hw enthalpy of boiler feed-water (after deaeration) bull nb thermal efficiency of boiler Often this thermal efficiency only takes into account the losses of heat in the stack of the boiler The deaerator is often not seen as part of the boiler (often this deaerator is common to many boilers and furnaces) Hence the following energy inputs are sometimes not taken into account for defining the energy value of steam bull energy required to pump boiler feed-water to operating pressure of the boiler bull heat added to boiler feed-water to bring it to the temperature of the deaerator bull steam sparged in the deaerator to remove oxygen from the boiler feed-water bull energy consumed by the air fan providing forced draft to the boiler

The difference in the energy required to produce the steam and the energetic value of the steam will then be counted at the site level rather than at the production process level At site level the steam will be allocated to the utilities plant (see Section 224) This is in principle not a problem The approach presented in Equation 22 and Equation 24 allows measurements to be made in the improvement of energy efficiency of a process itself and decoupling it from improvements in the energy efficiency of the steam generation process However again for a comparison between different plants making the same product one needs to make a comparison based on the same assumptions for the energetic value determination of steam

6 Load factor the reduction of the specific energy consumption (energy intensity factor EIF) with an increasing production rate is quite normal and is caused by two factors bull the production equipment will be operating for longer periods when the production rate is

high This means that the idling periods become shorter Some types of equipment run continuously even during non-production times This period will be reduced when the non-production time gets shorter (see Figure 214)

bull there is a base energy consumption that does not depend on the utilisation of production capacity This consumption is related to the use of lighting fans for ventilation office machines etc Neither is the heating of the premises dependant on the production but rather on the outdoor temperature as is shown in Figure 216 At higher production rates the consumption will be spread over more tonnes of products

This will be taken into account by the sectorsite-specific correction factor

7 Standards For some components and systems there are already energy efficiency standards (eg boilers motors) which are minimum requirements for appliances and systems

Chapter 2

SSEIPPCBENE_Draft_1 Version April 2006 45

233 Structural issues In addition to items dealt within Sections 231 and 232 related to internal issues to be decided when deciding on energy efficiency indicators there are several more structural issues which influence energy efficiency and should be considered and understood when deciding the system boundaries In this section there are some examples of issues companies may face and when decisions must be made on how these measures and changes influence the energy efficiency and how to update the indicators not to lose transparency However in all cases if structural changes are implemented also reference performance for energy indicators should be updated The origin and changes in energy efficiency are sometimes difficult to interpret The factors to influence energy efficiency can be active measures of company policy to improve energy efficiency by investments in processes or utilities or some measures over which the company does not have full control Effects by improvements of practices are in every case difficult to measure evaluate and maintain The decision of system boundaries and energy vectors (energy flows) should be made in a transparent way to follow the logic and decide what the real energy efficiency measures are and what the structural changes In some cases structural changes may improve energy efficiency and in some cases not this also depends on the system boundary When changes happen it should be easy to update the data Some examples follow and relate to the manufacturing and process industries In these cases system boundaries are drawn around the company If system boundaries are different eg extended to cover energy production plants in the country the recommendationoutcome would be different

1 Changes in the utilisation of production capacity Changes in production may have a significant impact on specific energy consumption Such changes are often caused by fluctuations on the market the competitiveness of the company and the buyersrsquo demand for the product In cases when the changes are due to market fluctuations and beyond the companyrsquos control they should not be quoted as energy efficiency measures If on the other hand the utilisation of capacity will be changed due to improved production planning meaning eg that the plant will be operated more intensely during fewer shifts this change should be regarded as an action to improve the energy efficiency (see Figure 213)

2 Changes in production technology Changes in production technology may be carried through eg as a result of technical development or because of new components or technical systems being available on the market Obsolete technical systems may need to be replaced and new control systems may need to be introduced to improve the production efficiency The introduction of such changes of production technology may also lead to improvements of energy efficiency Changes in production technology leading to more efficient energy use will be regarded as measures for energy efficiency improvements

3 Product development In some cases new units may need to be added to a production process to meet the market demand or to comply with new product specifications or with environmental requirements In these cases the EEI may deteriorate after the new unit has been put into operation because the new unit requires additional energy to work This does not mean that the site has suddenly neglected its management of energy

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46 Version April 2006 SSEIPPCBENE_Draft_1

An example of this situation was the adaptation of the refineries in years 2000 ndash 2005 to meet the new fuel specifications (low sulphur diesel and gasoline) set by the EURO IV regulation which has led to an increase of the refineries energy consumption Another example is from the pulp and paper industry which makes improvements of the fibers used in the process which leads to a reduction of energy use Somewhat later the quality of the finished product was also improved and this required an increased grinding After these two steps in technical development it turns out that the total energy use has increased

4 Lifecycle of a product A steel industry improves the strength of the delivered steel products The energy consumption in the new processes will increase The customers can reduce the plate thicknesses in their products by several tens of per cents The steel industry will experience an increase of the energy consumption per tonne product whereas the customers will benefit from the weight reductions in their final products

5 Changes in the production layout Changes in the production layout may eg mean that unprofitable production lines will be shut down media support systems will be exchanged similar lines of business will be merged etc Energy consumption will be changed as a consequence but this change will if regarded from a company standpoint be looked upon as a secondary effect Changes in the production layout can also be regarded to be measures for energy efficiency improvements

6 Close down of the manufacturing of a high energy product A company closes down the manufacturing of a product that requires high energy input Both the total and the specific energy consumption will be reduced This can be claimed to be a measure to improve the energy efficiency in spite of the fact that no other measures have been taken

7 Outsourcing By outsourcing the supply of media a company could eg shut off its compressed air centre The energy consumption could thus be reduced by buying compressed air from an external source The energy use will of course be increase by the supplier of compressed air The change must be clearly taken into account in the updating of energy efficiency indicators but it is not an energy efficiency measure

8 Laying out of process steps to other companies A company may for instance lay out the enamelling of plates to another company This is an example of an energy intensive process that is moved out of the first company but should not be looked upon as an action for energy efficiency improvements An automobile industry decides to increase their purchase of components instead of manufacturing such components themselves The result will be that the total and the specific energy consumption will decrease This must be taken into account in the updating of energy efficiency indicators

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9 Energy integration Internal power production without the additional supply of primary energy sources is an obvious means of improving energy efficiency If it is connected with an exchange of energy with surrounding enterprises system boundaries need to be defined and possible ambiguities settled When comparing electric energy with primary energy sources a conversion factor needs to be applied In the case of an additional supply of primary energy to a CHP plant in the company this may be regarded as an energy efficiency improvement

10 Use of oxygen in a combustion plant A company that increases the use of oxygen in a combustion plant will increase combustion efficiency and reduce fuel purchases Oxygen is not denoted as an energy source and the company may claim that they have improved their energy efficiency

11 Site or company integration Over the last few decades integration of industries has developed eg chemical sites with a high degree of integration have been formed This strategy offers considerable economic advantages This has resulted in complex sites with many operators present and with the utilities being generated either by one of these operators or even by a third party It may also result in complex energy flows between the different operators In general these big integrated complexes offer the highest potential for an efficient use of energy through integration However special caution is called for when defining the system boundary for energy efficiency for such complex sites In an isolated examination of a production process certain energy uses might seem inefficient even though they constitute a highly efficient approach within the integrated system of the site This may result in a situation where single operators are not always operating at their most optimum energy efficiency point but are compensated via commercial incentives in order to obtain the most competitive commercial environment for the integration of the site as a whole Some examples of benefits due to integration are bull the use of steam in a drying process seems to be less energy efficient than the direct use of

natural gas However when considering that this low pressure steam stems from a CHP process combined with highly efficient electricity generation the question of energy efficiency must be viewed in a different light

bull cogeneration plants located at the production site are not always owned by the production site but are often a joint venture with the local electricity generation company whereby the steam is owned by the site operator and the electricity is owned by the electricity company Care should therefore be taken in how these facilities are accounted for

bull when electricity is generated and consumed at the same site much lower transmission losses are expected and then the conclusion is evident that energy efficiency at integrated sites ndash which are quite common at chemical industry locations ndash is usually very high

bull within a highly integrated system residues from production processes are returned into the energy cycle Some examples are the return of waste heat steam into the steam network the use of hydrogen from the electrolysis process as a fuel substitute gas in the power plant process or as a chemical (eg raw material in hydrogen peroxide production) and the incineration of production residues in power plant boilers

All this makes it obvious that selecting appropriate system boundaries to define the energy efficiency of production processes is a sensitive matter

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48 Version April 2006 SSEIPPCBENE_Draft_1

24 Examples of application of energy efficiency 241 Mineral oil refineries The refineries already take seriously into account energy efficiency issues because energy costs represent more than 50 of global operating costs On a single refinery level energy efficiency can be followed by the energy intensity factor as defined in Section 222 In fact it is simpler to use the ratio between globally consumed energy on the site to the amount of treated crude which is equivalent to the EIF Following this ratio against time requires interpretation in order to clarify what comes from energy management and what comes from other factors However this ratio cannot be used for the purpose of comparing the energetic performance of different refineries as all refineries are different in complexities schemes processed crudes and production mixes All these parameters affect the energy needs of the refineries An attempt to catch this complexity is the Solomon Energy Benchmark for refineries For refineries Solomon associates have introduced the concept of the energy intensity index (EII) Solomon associates carry out a worldwide benchmark study of refineries every two years It covers all aspects such as capacity maintenance costs operational expenditure and also energy efficiency The energy efficiency is measured via the EII indicator which is defined as follows

Total actual refinery energy consumed EII = 100 x

Σ(Unit utilised capacity x Unit energy standard) + Sensible heat + Offsite energy

Equation 29 In Equation 29 bull the numerator is the total actual refinery energy consumption (expressed in lower heating

value) and equals the total consumption of fuelelectricity (both import and internal generation) but also takes into account any export of steam andor electricity Electricity from the external grid is converted to primary energy using a standard efficiency factor of 375

bull the denominator is the standard energy consumption according to Solomon (called guide energy) and consists of three main elements o the sum of the guide energies for each of the production units this guide energies are

calculated by multiplying the unit utilised capacity (normal throughput or feed rate) with a unit specific energy standard factor provided by Solomon for each unit For some production units this energy factor depends on feed quality (eg crude density)operation severity (catalytic reformers catalytic crackers etc)type of production facility etc These guide energies per unit are summed to give the total standard energy consumption for all of the refineries production facilities according to Solomon

o a sensible heat factor this factor accounts for the energy required to raise the plant input from ambient temperature to 1044 degC The basis for the plant input is all gross raw material input streams (and their respective densities) that are lsquoprocessedrsquo in process units Blend stocks are not taken into account

o an offsite energy factor this factor accounts for the energy consumed in utility distribution systems and operation of product blending tank farms (tank heating heating of rundown lines terminalling facilities) and environmental facilities The basis for the calculation is the raw material input to process units as well as to blending operations and a complexity factor of the refinery

The EII is dimensionless and in contrast to the definition of EEI presented in Section 222 decreases with increasing energy efficiency

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The EII attempts to compare the energy efficiencies of refineries having different complexities and different units Still this tool is considered by the refining industry as an imperfect tool for comparison purposes at best Some refineries that have a poor EII have few opportunities for improving energy efficiency whereas others with a good EII sometimes still have a large potential for improvement Moreover the EII does not give a good insight to the areasunits that need improvement The detailed breakdown of the site into main production units can be of more help in this respect to identify opportunities for improving energy efficiency

242 Ethylene cracker Ethylene crackers convert feedstock coming from the refinery into ethylene and propylene which form the main feedstock for the polymers industry Ethylene crackers are highly energy intensive Energy costs represent more than 50 of the operational costs of a unit Feedstocks (Fi) typically are naphtha LPG and gasoil coming from refineries The main products (P1) are ethylene and propylene (see Figure 22) Within the industry however it is the custom to add three other high value products to the main products for comparison purposes butadiene benzene and hydrogen Butadiene and benzene do not in fact come out as pure products in a cracker Butadiene is part of the C4 stream and benzene of the cracker gasoline stream They are usually extracted in dedicated extraction units which do not form part of the overall picture of the ethylene crackers Usually the ratio of these high value products to ethylene varies in a narrow window (between 17 and 23) and will depend on cracking conditions and feedstock qualitytype For plants where the economics are mostly driven by ethylene production a more meaningful energy indicator might be to divide energy use by ethylene production rather than by high value chemicals Energy vectors

bull steam a typical ethylene cracker would usually have several steam levels (a high pressure level of approx 100 barg a medium pressure level of approx 20 barg and low pressure level of approx 4 barg) Depending on the configuration the cracker will import steam at some levels and export at other levels

bull electricity most crackers are net electricity consumers Those equipped with cogeneration may be net exporters of electricity Within the industry the convention is to use a conversion factor of 375 to convert electricity to primary energy when comparing different plants

bull hot water most crackers produce relatively large amounts of hot water However in most cases the temperature of this hot water is too low for use by other plants but in some cases integration with other plants or outside consumers is possible In this case a credit should be given for export of these calories So an improvement of energy efficiency is determined by an lsquoexternalrsquo circumstance independent of the lsquointrinsicrsquo performance characteristics of the unit under examination that is the actual possibility of using an output stream for a duty that otherwise should be satisfied with additional primary energy As a consequence two units with the same lsquointrinsicrsquo performancersquo would be rated differently if only one of them can find an energy use for one of its output streams (heat integration)

bull fuel most crackers produce a liquid fuel (pyrolysis fuel oil) and gaseous fuel (a methane rich mixture) Most of the gaseous fuel is recycled to fire the ethylene furnaces Depending on the configuration and mode of operation the gaseous fuel produced may be self sufficient to fire all the furnaces and the rest of fuel gas is exported or there may still be a deficit so the import of an external fuel is required which is typically natural gas Only the fuel consumed internally by the ethylene cracker is taken into account in the energy balance All fuels exported are counted as products (this is logic as the fuel value was already present in the feedstock)

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50 Version April 2006 SSEIPPCBENE_Draft_1

bull cooling water all crackers use cooling water Sometimes cooling towers are part of the ethylene cracker however this cooling water comes from cooling towers which also supply cooling water to other production units In this case the energy related to the production of cooling water is often not reported when calculating the energy efficiency of the process

bull ethylene processes also use other utilities such as N2 and compressed air Often these utilities are produced centrally on the site or by a third party The energy related to these utilities is often not counted

243 VAM production Some of the components of the proposed Equation 24 Section 223 to calculate the energy intensity factor (EIF) may not be applicable for each process Therefore it has to be modified to the prevailing needs As an example a vinyl acetate monomer (VAM) plant is taken Several components of a VAM plant are not being measured or quantified (here marked with ()) whereas others can easily be named (here marked with ()) see Figure 211

VAM plant

Electrical power

Steam

Cooling water

Utilities

Catalyst inhibitor

Ethylene

Acetic acid

Oxygen

Recycled steam

Condensate

Cooling water return

Light ends

Heavy ends

Purge gas

Waste gas

Heat losses (isolation)

VAM

Water

CO2

Input Output

Figure 211 Inputs and outputs for a vinyl acetate monomer (VAM) plant

As stated in Section 223 heat losses via cooling water return and isolation should never be counted in the EIF or EEI Waste gas and purge gas should not be counted if it is incinerated without heat recovery For those terms it may however be useful to gain some insight into their order of magnitude to verify the economic potential needed to reduce these losses or waste streams In contrast more reflection is required on the other terms such as light and heavy ends or if waste andor purge gas are valorised in other processes In the proposed Equation 24 these streams were not included as it is assumed that the fuel content of these streams is already present in the feedstock However it is the responsibility of the operator to define how to account for these terms

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244 A rolling mill in a steel works The feeding to a rolling mill consists of approximately 2 decimetres thick flat steel plates that are to be rolled out to bands with a thickness of a few millimetres The rolling mill consists of furnaces rolling mill equipment cooling equipment and support systems including pumps fans hydraulics and lubricating systems lights a mechanical workshop staff space changing rooms etc A flow chart of a rolling mill is shown in Figure 212

Furnace

Furnace

Furnace

Rolling equipment

Boiler

Compressor

Cooling bed

Hundreds of pumps and fans at different locationsHundreds of pumps and fans at different locations

Slabs (materialsto be rolled)

Liquefiedpetroleum gas Electricity Cooling water Air

Exhaustgases

Air Scrap(reject

products)

Coolingwater Heat

lossesRolled

products

Figure 212 Flow chart of a rolling mill In this case several different primary energy sources are involved However the following discussion is restricted to the use of electric energy The number of electrically driven components or subsystems in a rolling mill can be estimated at more than one thousand The electric energy consumption can be registered easily with reliable electricity meters The steel production may either mean the weight of slabs entering the rolling mill or the weight of rolled and approved final products The difference corresponds to the weight of scraps that may fall at different stages in the rolling mill An analysis of data taken from an existing rolling mill during a period of 11 weeks was made and some of the results are shown in Figure 213 The energy consumption varied between around 120 and 80 kWh per tonne delivered products dependent on how many tonnes that were produced per week The average consumption was thus 100 kWhtonne and the variation plusmn 20 No energy saving measures were taken during this period

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52 Version April 2006 SSEIPPCBENE_Draft_1

Specific energy consumption in a rolling mill

200

600

1000

1400

010000 20000

kWh

tonn

e

Tonnesweek

Figure 213 Specific energy consumption in a rolling mill

The reduction of the specific energy consumption (energy intensity factor EIF) with an increasing production rate is quite normal and is caused by two factors bull the production equipment will be operating for longer periods when the production rate is

high This means that the idling periods become shorter Some types of equipment are running continuously even during non-production time This type of energy consumption will be reduced when the non-production time gets shorter

bull there is a base energy consumption that does not depend on the utilisation of production capacity This consumption is related to the use of lighting fans for ventilation office machines etc At higher production rates the consumption will be spread over more tonnes of products

The decrease in the specific energy consumption with increasing production rate is thus caused by fluctuations in market conditions which are beyond the companyrsquos control The question is if increasing the production and thereby reducing the specific energy consumption should be regarded as a measure for energy efficiency improvement

A program for improvement of the energy efficiency was later carried out at the rolling mill A number of measures were taken with the aim of decreasing the energy consumption and the results of these measures are illustrated in Figure 214

In this case a direct result of the energy saving measures could be observed The results appeared to be largely independent of the production rate As can be seen in Figure 214 it is possible to separate the results of energy saving efforts and results caused by other factors such as the utilisation of capacity

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Specific energy consumption in a rolling mill

10000 20000

Tonnesweek

kWh

tonn

e Energy efficiencyImprovements as aresult of an energysaving programme

Reduction of the energyconsumption as a resultof increased production

1400

1000

600

0

200

Figure 214 Specific energy consumption in a rolling mill

It is also obvious that interpretation difficulties will arise when comparing the specific energy consumption month by month or year by year The specific energy consumption may very well increase from one period to the next though a number of energy saving measures have been taken In this case the effect of such measures is not large enough to compensate for the increase in energy consumption due to low production rates

245 Heating of premises The heating of premises represents another case where the variation of the energy consumption to a great extent is beyond the userrsquos control The energy use is strongly dependent on the outdoor temperature as is shown in Figure 215

-20 0

Energy consumption forheating (MWhweek)

Weekly average outdoortemperature (degC)

Figure 215 Energy consumption depending on outdoor temperature

If measures like heat recovery from the outlet of ventilation air or improvement of house insulation are taken the graphline in Figure 215 will be moved downwards as seen in Figure 216 Estimates of the results of energy saving measures must thus be made with due consideration to outdoor temperature variations

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54 Version April 2006 SSEIPPCBENE_Draft_1

-20 0

Energy consumption forheating MWhweek

Reduction of energyconsumption due toenergy saving measures

Weekly average outdoortemperature (degC)

Figure 216 Energy consumption depending on outdoor temperature

There are apparent similarities between the diagrams in Figure 214 and Figure 216 The output value is the production of steel and the provision of a comfortable indoor temperature respectively In both cases the operator of the system has no control of the most important parameters customersrsquo purchasing of steel products and the outdoor temperature respectively

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3 ENERGY MANAGEMENT IN INDUSTRIAL INSTALLATIONS [6 Cefic 2005] [9 Bolder 2003] [89 European Commission 2004] [92 Motiva Oy 2005] [96 Honskus 2006] [108 Intelligent Energy - Europe 2005] This chapter deals with energy management in industrial installations in broad terms It explains why good structured management is important and which issues will be considered and taken into account in a good systemstructure It covers the elements which are crucial to manage energy issues efficiently both from an environmental and economic point of view It gives examples of good management structures approaches audits methodologies and other tools which could be implemented to improve energy efficiency Detailed descriptions of the tools is in the Section 32 dealing with methodologies Systematic and transparent ways to deal with energy issues are essential to reach the best environmental and economic results Energy is as any other valuable raw material resource required to run a business ndash not a mere overhead and part of business maintenance Energy has costs and environmental impacts and need to be managed well in order to increase the businessrsquo profitability and competitiveness and to mitigate the seriousness of these impacts All industrial companies can save energy by applying the same sound management principles and techniques they use elsewhere in the business for key resources such as raw material and labour as well as for environment and health and safety These management practices include full managerial accountability for energy use The management of energy consumption and costs eliminates waste and brings in ongoing cumulative savings

31 The structure and the content of energy management 311 General features and factors Energy management means structured attention to energy with the objective of continuously reducing energy consumption and improving efficiency in production and utilities and sustaining the achieved improvements Energy management is a useful instrument to improve the efficiency of energy systems both at company and site level It provides a structure and a basis for the determination of the current energy efficiency defining possibilities for improvement and ensuring continuous improvement All effective energy (and environmental) management standards programmes and guides contain the notion of continuous improvement meaning that energy management is a process not a project which eventually comes to an end Energy management does not only focus on technical possibilities (such as the installation of a special technique) but also takes into consideration the organisation the motivation of employees good practices and the co-operation of different departments and costs Very often energy management (energy issues) is an integral part of an environmental management system or other management system Energy management can be carried out at different levels which is expressed in following bull lsquolightrsquo energy management which could be described as lsquomanagement by intuitionrsquo bull energy conservation plans (ECP) based on the plan-do-check-act cycle (see Figure 31) of

continuous improvement bull energy management based on national standards (such as the Danish DS 2403 IR and SE)

or international guidelines (international standards or guidelines on energy management) However the company may not seek certification

bull energy management following a specific standard (and certified)

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56 Version April 2006 SSEIPPCBENE_Draft_1

Table 31 illustrates different levels of energy management in more detail It should be noticed that level 4 shows the best performance

Level Energy policy Organising Motivation Information systems

Marketing Investment

4 Energy policy action plans and regular reviews have the commitment of top management as part of an environmental strategy

Energy management fully integrated into managementstructure Clear delegation of responsibility for energy consumption

Formal and informal channels of communication regularly exploited by energy manager and energy staff at all levels

Comprehensive system sets targets monitors consumption identifies faults quantifies savings and provides budget tracking

Marketing the value of energy efficiency and the performance of energy management both within the organisation and outside

Positive discrimination in favour of lsquogreenrsquoschemes with detailed investment appraisal of all new-build and refurbishment opportunities

3 Formal energy policy but no active commitment from top management

Energy manager accountable to energy committee representing all users chaired by a member of the managing board

Energy committee used as main channel together with direct contact with major users

MampT reports for individual premises based on sub-metering but savings not reported effectively to users

Programme of staff awareness and regular publicity campaigns

Same payback criteria employed as for all other investment

2 Unadoptedenergy policy set by energy manager or departmental manager

Energy manager in post reporting to ad-hoc committee but line management and authority are unclear

Contact with major users through ad -hoc committee chaired by senior departmental manager

Monitoring and targeting reports based on supply meter data Energy unit has ad-hoc involvement in budget setting

Some ad -hoc staff awareness training

Investment using short term payback criteria only

1 An unwritten set of guidelines

Energy management is the part -time responsibility of someone with limited authority or influence

Informal contacts between engineer and a few users

Cost reporting based on invoice data Engineer compiles reports for internal use within technical department

Informal contacts used to promote energy efficiency

Only low cost measures taken

0 No explicit policy No energy management or any formal delegation of responsibility for energyconsumption

No contact with users

No information system No accounting for energy consumption

No promotion of energy efficiency

No investment in increasing energy efficiency in premises

MampT ndash monitoring and targeting

Table 31 Energy management matrix [107 Good Practice Guide 2004]

To illustrate the process thinking different models have been developed but one of the most commonly used is the plan-do-check-act (PDCA) 1 cycle (see Figure 31) The PDCA cycle is often known by company management from other contexts but energy This approach is also in line with the most commonly used management approaches and standards that are relevant to industry The PDCA cycle provides a framework for the continuous improvement of a process or system The cycle is designed as a dynamic model where the completion of one turn of the cycle flows into the beginning of the next

1 The PDCA Cycle was developed by Walter Shewhart the pioneering statistician who developed statistical process control in the Bell Laboratories in the US during the 1930s Therefore it is also often referred to as lsquothe Shewhart Cyclersquo It was taken up and promoted very effectively from the 1950s on by a famous quality management authority W Edwards Deming and is consequently known by many as lsquothe Deming Wheelrsquo

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SSEIPPCBENE_Draft_1 Version April 2006 57

ACT PLAN

CHECK DO

Figure 31 The plan-do-check-act-cycle (PDCA) [108 Intelligent Energy - Europe 2005]

Usually good energy management practices are based on a standard or a specification which is derived from something which is already known in particular the ISO 9001 management standard and the related environmental energy management standard ISO 14001 or EMAS An increasingly popular approach are also specific energy management standards which have been developed in three EU countries (DK SE and IE) and which (as a standard or as guidelines) are also planned by the CENCENELEC Successful implementation of energy management requires commitment by the company management conducting an energy audit analysis and target setting for example by making an energy conservation plan executing the actions needed to fulfil the targets setting up a monitoringmeasuring system motivating staff and having management reviews Finally it is necessary to implement the energy management system or a corresponding structure throughout the company on a permanent basis to ensure the continuous follow-up and improvement of energy efficiency Figure 32 illustrates the continuous improvement of an energy management system

Plan ndashgt Do ndashgt Check ndashgt Act approach

5 Management review (improve) (ACT)bull Management reportingbull Deviation reportsbull Review of Targets

4 Control and corrective actions (monitor) (CHECK)bull Control of deviations + corrective actionsbull Internal and external system auditbull Benchmarking

1 Energy policy (commitment)bull Legislation LTAbull Targets CO2 or energy efficiencybull BAT LCA LCC

2 PLANbull Targets and plan of action (ECP)bull EM system standards design

3 Implementation and operation (DO)bull Organisation and responsibilitiesbull Motivating awards trainingbull Energy monitoring and reportingbull Energy purchase reporting of LTA

Figure 32 Continuous improvement of an energy management system [92 Motiva Oy 2005]

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58 Version April 2006 SSEIPPCBENE_Draft_1

Energy management can be used in all companies because it provides a general approach and structure that offers flexibility to accommodate any specific branch of business With respect to corporate management this may be understood as being either the management of the holding company or of a business unit or of a site In the following sections a good environmental structure is dealt with on the basis of a management system It expresses what items a good energy management system includes A good energy management structure is based on PDCA cycle and contains corporate commitment planning and implementing of the structure to manage energy issues concrete measures tools and resources and monitoring both technical and management commitments

312 Commitment of the top management Top management commitment is the precondition for successful energy management If energy efficiency is high on the company agenda the necessary driving forces are created for the organisation Long range visions must be defined by top management In addition the corporate management needs to communicate the commitment of resources ndash people and financial - towards this vision This commitment enables the build-up of the necessary organisational structure and some benefits are bull make it clear to the staff that energy efficiency is to be taken seriously and will give it a

higher status bull organisationally this gives the company a platform where energy problems crosscutting

various departments can be solved bull investment decisions can be taken at the appropriate level bull prevents decline in attention to energy efficiency This commitment also needs to be visible and agreed at the highest levels in the company The vision needs to be clear and visible to all employees This includes reviews of progress by high level management of the company Reviews are part of the PDCA cycle Top management also needs to help initiate an organisational structure that can work towards the goal in an efficient productive manner A culture needs to be created and demonstrated that keeps the energy topic an everyday topic This means that enough resources are allocated and good practices are implemented and kept going If the company has included energy issues in its environmental management system (or other management system) the commitment of top management is always there and is included in company energy policy As much as possible existing structures should be used although new structures can also be considered If the company has a certified (ISO EMAS) environmental management system this will automatically include the continuous improvement approach

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SSEIPPCBENE_Draft_1 Version April 2006 59

The following bullets list success factors that motivate top management to carry out energy management bull participation in a well designed long-term agreement can be a good driver to work on

energy efficiency bull need to gain competitiveness by reducing production costs as the competition in the

European markets is increasing bull increasing energy prices are a driving force bull new investments in industry enhance the penetration of new technologies in the market

As a rule new technologies are more energy efficient bull in some countries new legislation and regulations are preconditions for improving energy

efficiency bull liberalised energy markets with new emerging energy services as well as public promotion

of cogeneration and renewable energies create new opportunities for effective energy management

313 Planning To implement the top management commitment which is included in companycorporation energy policy in practice in order to achieve results in energy efficiency the company has to start and continue to do proper planning A company needs to know where is it and what it is working towards A clear measurable and traceable common goal with a timeline and defined improvement steps is the first step on the road to implementation When deciding on a definition for the timeline and the improvement steps it is important that all relevant employees co-operate and work as a team The work starts by doing the initial energy audit and continues by deciding on targets measures and resources The following list of success factors for good energy management is identified bull case studies of good practices are helpful bull work in a methodical way do not implement measures in a random way

3131 Initial energy audit Essential for this first step is the inventory of actual status (absolute energy consumption flow of energies consumers energy accounting system) versus a reference (eg competition thermodynamic targets best available techniques trends over time) With the help of this information and the company vision the energy goals can be developed The tools and methodologies for inventories are dealt with in detail in Section 32 The target of the initial energy audit is to identify a companyrsquos energy consumptions and find measures to decrease the consumption Based on this information the company can prioritise and decide on efficiency goals In the audit relevant action areas for improvement and energy efficiency opportunities can be identified

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60 Version April 2006 SSEIPPCBENE_Draft_1

The initial energy audit contains the following items bull the identification of areas or activities with significant energy consumptions bull the collection and analysis of energy consumption data bull the identification of energy efficiency opportunities bull the identification of legal and other requirements bull the determination of baseline energy consumptions bull the identification of appropriate energy efficiency indicators bull the identification of practices related to energy issues bull identification with legal and other requirements to which the company subscribes and are

applicable to the energy aspects of its activities bull the documentation of the energy audit and its revisions Different types of audits are dealt with in Section 321

3132 Energy performance targets To set up performance targets and thestructure to implement those is a key issue in improving energy efficiency in a company The performance targets will be set for processes and other activities which have significant energy consumption and conservation potential and are related with legal or other rules and requirements It is important to understand the character of the individual business units to improve their energy efficiency On the other hand only an understanding of the interrelation of these units will guarantee the overall best results bull goal setting needs to take into account the other units on the site and even in the local

environment bull the definition of plans and distribution of resources needs to bear in mind the corporate

network conditions bull waste from one unit can be valorised as an energy carrier in another unit The energy performance targets are clearly defined and measurable They are documented and there is a time frame for their achievement Energy management achievements are monitored and benchmarked systematically The company also sets and revises its energy performance targets systematically according to bull the energy consumption significance bull the relevant legal aspects bull the companyrsquos current technological operational and financial capacity The energy performance targets are appropriate for benchmarking and consistent with the energy policy Appropriate indicators are very important for understanding the current situation and also for checking progress versus goals Thus all necessary data need to be collected stored and communicated constantly and consistently to calculate these indicators For finding measures to improve energy efficiency there are different tools like Pinch methodology audits etc These are dealt with in more detail in Section 32

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SSEIPPCBENE_Draft_1 Version April 2006 61

Continuous improvement is an essential element to drive energy efficiency Good energy management needs to follow the plan-do-check-act cycle which should be included in all management systems It guarantees that task and responsibilities are defined and progress is checked on a regular basis When operating within this cycle the actual performance is compared to planned performance Depending on results of this cycle further measures and tasks need to be defined or redefined

3133 Action plan The company will establish and maintain an action plan for achieving its energy performance targets and the realisation of the energy policy The action plan will include bull actions for the achievement of the energy targets bull the means and resources for each action bull designation of responsibility for each action bull determination of the time frame for each action bull deciding the indicators bull means to monitor indicators and targets The action plan is consistent with the companyrsquos energy policy and its current technical financial and operational capacity

314 Doing To achieve the goals it is necessary to have a proper action plan and a focused organisation Existing structures (like qualityenvironmental management) or it can be helpful to develop a new (independent) structure The tools that are used to drive energy efficiency can be energy specific like Pinch methodology energy audits and studies or come from general management toolsets which are either externally or internally developed The following list of success factors for good energy management is identified bull guide the company step-by-step through the implementation of energy management is

useful Energy advisors and other helpdesks are instrumental in this process Practical action-specific programmes are better than generic support and guidance

bull give the company access to tools that are easy to use for example o checklist for the level of energy management o tools for the implementation of energy management o tools for dailymonthlyyearly energy monitoring o reporting modules (eg for the competent authorities)

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3141 Structures and responsibilities The structures will allow for implementation and control of all aspects of the action plan like technical measures training of employees improvement of internal procedures communication and tracking The company will define and document roles and responsibilities of the staff and then communicate them in order to facilitate effective energy management Furthermore top management will provide resources essential to the implementation and control of the energy management systemstructure eg resources include human resources specialised skills technology and financial resources It will be beneficial to appoint an Energy Manager who irrespective of other responsibilities will have defined roles responsibilities and authority for bull the continuous improvement of the companyrsquos energy performance bull the implementation of the energy management system bull the monitoring benchmarking and reporting of the energy performance bull the staff involvement in the effort for energy performance improvement The company should assign responsibilities according to function level education experience personality and capability in order to achieve efficient implementation of the energy management system

3142 Awareness raising and capacity building The best energy efficiency cannot be achieved only by technological measures but also good practices and staff involvement are needed Benefits of investments may even be destroyed if human resources are not included and motivated It is crucial that staff are trained The company will communicate energy policy to all the personnel in order to inform and encourage personnel to contribute to energy performance improvement The company will inform its personnel about the following energy related issues bull the importance of energy efficiency to the company bull the companyrsquos efforts towards energy efficiency bull the consequences of their work activities in energy consumption bull their roles and responsibilities in the effort towards energy efficiency The company will identify the key personnel whose work significantly affects energy performance and specific training should be organised for these people in order for them to be efficient in energy management Appropriate training activities should be planned and carried out

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3143 Communication and motivation Communication and motivation are crucial tools so that modern companies can implement all kinds of issues Communication is a key element because it provides feedback to all partners about their performance Communication is used positively to provide recognition of achievers Communication includes bull inside an individual company all staff should be involved bull involving several companies from the same sector in a working group (energy networking)

to exchange experiences has proven useful The companies should all be at the same level of energy management implementation Networking is especially useful for solving typical difficulties such as defining an energy efficiency index or setting up an energy monitoring system Networking may also introduce an element of competition in energy efficiency and provide a platform for negotiation with potential energy efficient equipment or service suppliers

bull positive effects should be made clearly visible Awards for best practices are a possibility to implement this

Well structured communication secures the flow of information of goalscommitments as well as the achieved results The company will implement practices that ensure efficient two-way internal communication concerning the effort towards energy efficiency The company will also inform its staff about energy efficiency and systematically support encourage and motivate them to contribute to energy efficiency by conserving energy preventing unnecessary consumption working efficiently and making recommendations and observations Communication is also used to encourage the exchange of information with other companies - to swap best practice ideas and to pass success stories from one company to another etc The possible means of communication are a system of specific energy consumption numbers (daily weekly monthly yearly) over time or in correlation with important parameters (like production rate weather conditions) combined with success stories in periodically published reports Graphics are an excellent way to provide information

315 Checking The company cannot demonstrate its energy efficiency and improve its energy performance if it is not monitoring and measuring its energy flows and other important indicators This enables feedback to the management on the effectiveness of energy efficiency measures Take care that those responsible for energy efficiency have the ability to control it This means that good monitoring (lsquoif you canrsquot measure it you canrsquot manage itrsquo) and reporting are essential

3151 Monitoring and measurement Monitoring is an important element of the PDCA cycle and a prerequisite for demonstration of efficient energy use and benchmarking Monitoring is planned together with energy efficiency indicators

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64 Version April 2006 SSEIPPCBENE_Draft_1

A company will systematically measure and monitor its energy flows and other relevant factors which have been identified as crucial to follow Tools for monitoring are dealt with in Section 32 Appropriate energy indicators (see Section 22) are periodically calculated registered analysed and reported A company will evaluate its energy performance according to its energy targets Actions and practices will be amended for the achievement of energy targets whenever necessary A company will have practices to detect and investigate non-conformances that significantly affect its energy efficiency and will respond to them in order to minimise their negative impacts Monitoring will be dealt with in more detail in Section 322 Information will be collected via an energy information system which will also analyse and report the results

3152 Records The company will keep records of its energy performance that are tailored to their energy management system requirements Records should be legible identifiable accessible and traceable to the relevant process activity or person

3153 Periodic energy audits In addition to initial energy audits the company will periodically perform different energy audits in order to bull determine its current energy performance bull check the systemrsquos implementation and maintenance bull compare results with system targets bull provide benchmarking information bull investigate problems and identify causes and weaknesses bull inform the management of the company bull find new measures to improve energy efficiency Energy audits are dealt with in Section 321

316 Acting The companyrsquos top management will periodically review the energy management system and the results to ensure its continuing suitability adequacy and effectiveness and to evaluate its performance via benchmarking The review process will ensure that the necessary information is collected to allow management perform this evaluation The management review will address the possible need for changes to energy management policy objectives and practices in the light of energy audits results changing conditions and the commitment to continual improvement of the companyrsquos energy performance

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SSEIPPCBENE_Draft_1 Version April 2006 65

317 Examples of energy management systems and its implementation No information provided We expect to include here real examples of application of energy management systems in different industrial sectors and companies This also includes bull all steps in the management cycle bull data of energy efficiency improvements bull economic data

32 Methodologies and tools for energy use optimisation and energy efficiency

This section describes the tools which have been developed to support energy management The following list shows various tools which have been identified and which are described in more detail in the succeeding sections bull energy audits bull energy monitoring bull energy models bull pinch methodology bull benchmarking bull e-learning bull checklists bull good housekeeping The different tools are described in a relevant and suitable way in every case

321 Energy audits [92 Motiva Oy 2005] [40 Meireles 2005] [31 Despretz ] [7 Lytras 2005] The term lsquoenergy auditrsquo is in principle well known and commonly used What is actually meant by the term in individual cases can in practise include an extremely wide range of different applications The variety within the family of energy audits should be understood as should the importance of also defining the the scope content and depth of the audit in more detail Audits are crucial tools in energy management Different types of audits (technical audit best practice audits management audits) may be used in different phases and four different purposes during the implementation of energy management systems An energy audit is a systematic analysis of energy usage which identifies the main areas operations and types of energy used in a unitprocesssite It may also identify the cost effective energy saving opportunities and report the findings

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3211 Audit models In most cases energy audit is one module among other energy efficiency activities Figure 33 shows the basic energy audit models

THE SCANNINGMODELS

THE ANALYSINGMODELS

The walk throughenergy audit

The preliminaryenergy audit

The selectiveenergy audit

The targetedenergy audit

The comprehensiveenergy audit

MAG

NIT

UD

E

AC

CU

RA

CY

VERTICAL HO

RIZ

ON

TAL

The systemSpecific Energy

Audit

Figure 33 Basic energy auditing models [92 Motiva Oy 2005]

An audit model is usually a standardised commonly known and commonly followed procedure with written guidelines The requirements are usually defined in the guidelinesstandards given by company itself or by the standardisation body An energy audit may cover a site or a building in various ways ndash the scope of audits may be different At the lsquonarrowestrsquo an energy audit covers typically only one specific system (or a process) and at the lsquowidestrsquo an energy audit covers everything inside the site fence Between these lsquonarrow and wide endsrsquo there are energy audits that deliberately ignore some areas or issues In most audits related to the implementation of standards there are clear requirements as to what audits should include Energy audits are used for different purposes either for pointing out the areas where savings can be made or for describing in detail the actual saving measures so that they can be easily implemented These properties of energy audit models are illustrated in Figure 34

NARROW WIDE

ROUGH COMB FINE COMB

TO POINT OUT TO PROPOSE

THE SCOPE

THE THOROUGHNESS

THE AIM

Every systemall sites

Detailed potentialassessment

Specific energysaving measures

Specific systemarea

General potentialassessment

General energysaving areas

Figure 34 The properties of energy audit models [7 Lytras 2005]

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SSEIPPCBENE_Draft_1 Version April 2006 67

This section presents the different energy audit models divided into two main classes according to their aim to the scanning energy audit models and to the analysing energy audit models (see Sections 32111 and 32112) Within these two classes the different models have been specified according to their scope and thoroughness The basic energy audit models are not used very often as such and therefore the models in actual use are different types basic model applications The applications have different features depending on an interface to the connected activities

32111 The scanning models The main aim of the scanning energy audit model is to point out areas where energy saving possibilities exist (or may exist) and also to point out the most obvious saving measures Scanning audits do not go deeply into the profitability of the areas pointed out or into the details of the suggested measures Before any action can be taken the areas pointed out need to be analysed further A scanning audit model is a good choice if large audit volumes need to be achieved in a short time These types of audits are usually quite cheap and quick to carry out From the companyrsquos point of view a scanning audit may not bring the expected results because it does not necessarily bring actual saving measures ready for implementation but usually suggests further analysis of key areas

Walk-through energy audit A walk-through energy audit is suitable for small and medium sized industrial sites if the production processes are not very complicated in the sense of primary and secondary energy flows A walk-through energy audit gives an overview of the energy use of the site points out the most obvious savings and also points out the needs for the next steps (supplementary lsquosecond-phasersquo audits) The walk-through energy audit has been used by ESCOs in the scanning phase of third party financing projects

Preliminary energy audit The scanning energy audit model for large sites is called the preliminary energy audit Audits of this type are typically used in the process industry Although the main aim of the preliminary energy audit is in line with the walk-through energy audit the size and type of the site requires a different approach Most of the work in the preliminary energy audit is in building up a reliable breakdown of the present total energy consumption and defining the areas of significant energy consumption and usually also of the probable energy saving measures The reporting also points out the areas where supplementary lsquosecond-phasersquo audits are needed and how they should be targeted (see Section 3131) The preliminary energy audit normally needs to be carried out by a team of experts Expertise is needed both on the auditing procedure itself as well as on the production process The preliminary energy audit always requires committed participation from the technical personnel of the site

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68 Version April 2006 SSEIPPCBENE_Draft_1

32112 The analysing models The analysing energy audit models produce detailed specifications for energy saving measures providing the audited client with enough information for decision-making Audits of this type are more expensive require more work and a longer time schedule but bring concrete suggestions on how to save energy From the companyrsquos point of view the saving potential can be seen and no additional surveys are needed The analysing models can be divided into two main types bull selective energy audits where the auditor is allowed to choose the main areas of interest bull targeted energy audits where the company has defined the main areas of interest

Selective energy audit The selective energy audit looks mainly for major savings and does not pay attention to minor saving measures This audit model is very cost effective when used by experienced auditors but may in the worst case be real lsquocream skimmingrsquo There is always the risk that when a few significant saving measures are found the rest will be ignored

Targeted energy audit The content of work in the targeted energy audit is specified by detailed guidelines from the company and this means that most of the systems to be covered by the targeted energy audit are known in advance The guidelines set by the Company may deliberately exclude some areas The reason for excluding certain areas may be that they are known to be normally non-cost relevant The targeted energy audit usually produces a consumption breakdown and includes detailed calculations on energy savings and investments If the guidelines are adequate the audit produces a standard report From the companyrsquos point of view the targeted energy audit is always a risk if quality control is neglected if there is no control on the auditorsrsquo work they may be tempted to slowly move towards the selective energy audit because this model always includes less work System specific energy auditAn example of the targeted energy audit at the simplest and smallest is the system specific energy audit This type of audit has a tightly limited target (one system device or process) but the thoroughness of the work is usually very high The benefit of this audit model is that it is possible to have the best expertise on the work normally better than what an average auditor can provide The system specific energy audit produces a detailed description of the system and points out all profitable saving measures with alternative options concerning the specific system One good option is to combine this kind of audit as a sub-model with some more comprehensive audit models System specific energy audits give high saving potentials compared to the energy use of the system The problem is that when looking at only one part of the site the lsquobigger picturersquo is missing and a risk of partial optimisation exists For example when only studying only energy efficiency of compressed air or cooling systems heat recovery opportunities cannot be evaluated because there is no knowledge as to where heat could be used in the most efficient way Energy systems are usually interrelated and seldom independent

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SSEIPPCBENE_Draft_1 Version April 2006 69

Comprenhensive energy audit A comprehensive energy audit is a targeted energy audit at the lsquowidestrsquo end of the scale it covers all energy usage of the site including mechanical and electrical systems process supply systems all energy using processes etc Some minor systems may be excluded but they should not really be relevant in proportion to the total energy consumption The clear difference to the targeted energy audit is that the targeted energy audit deliberately ignores some areas that are known and specified in advance and the comprehensive energy audit covers everything The starting point in this type of audit is always an analysis on the detailed breakdown of the total consumption The comprehensive energy audit comments on all systems using energy specified at the beginning - regardless if savings are found or not it points out all profitable saving measures and includes detailed calculations on energy savings and investment costs This model also creates a basis for a very standard and detailed reporting which brings some advantages to the company especially in quality control and monitoring

32113 The technical coverage of energy audit models Depending on the goals of the energy audit programme or activity the audit models can be defined to cover different aspects of the site If the main target of the programme is to achieve energy savings then all energy use should be analysed However if the main aim is to promote the use of renewable energy sources the viewpoint is slightly different The technical content of an audit model can be illustrated by a lsquobox-modelrsquo Figure 35 Figure 36 and Figure 37 give an idea of the different approaches

ENERGY PRODUCTION ON SITEENERGY PRODUCTION ON SITEBUILDING ENVELOPEBUILDING ENVELOPE

BUILDING SERVICE SYSTEMSBUILDING SERVICE SYSTEMS

PROCESS SUPPLY

PRODUCTIONPROCESSHEATING AND FUELS

WATER

ELECTRICITY

RENEWABLES

Figure 35 Coverage of an industrial site energy audit [7 Lytras 2005]

The comprehensive energy audit for an industrial site covers all energy use of process process supply systems building service systems and heat production

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70 Version April 2006 SSEIPPCBENE_Draft_1

ENERGY PRODUCTION ON SITEENERGY PRODUCTION ON SITEBUILDING ENVELOPEBUILDING ENVELOPE

BUILDING SERVICE SYSTEMSBUILDING SERVICE SYSTEMS

PROCESS SUPPLY

PRODUCTIONPROCESSHEATING AND FUELS

WATER

ELECTRICITY

RENEWABLES

Figure 36 Coverage of a district heating connected to a residential building energy audit [7 Lytras 2005]

In a district heating connected to a residential building the energy audit covers the total picture of the building service systems Electricity use by the residents is ignored

ENERGY PRODUCTION ON SITEENERGY PRODUCTION ON SITEBUILDING ENVELOPEBUILDING ENVELOPE

BUILDING SERVICE SYSTEMSBUILDING SERVICE SYSTEMS

PROCESS SUPPLY

PRODUCTIONPROCESSHEATING AND FUELS

WATER

ELECTRICITY

RENEWABLES

Figure 37 Coverage of a CHP plant energy audit [7 Lytras 2005]

In a CHP power plant energy audit the energy production process is analysed and the possibilities for using renewable are investigated

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SSEIPPCBENE_Draft_1 Version April 2006 71

3212 Audit tools Lot of tools have been developed to lsquostandardisersquo contents and approaches of audits Usually companies have tailor-made tools like checklists to use in auditing procedures The following paragraphs will describe some of the tools bull informationdocumentation on technical topics (eg ECOs1 branch specific) - this is

an information support document which is often based on case studies and intended to help in marketing the audits in view of successful examples The main target is the benefactor of the audit This document focuses on one particular technique andor a specific subsector (in the industry) and the information given is summarised mainly on results and interviews Depending on the accuracy of the information these tools can also be considered andor used as promotion support elements

bull audit guide or audit handbook energy management handbook ndash this is a core component of an energy audit scheme which is the basis of training sessions and is targeted essentially to auditors It explains and describes how an audit is to be made how the calculations are to be conducted the types and contents of the most frequently proposed energy conservation options (ECOs) Although auditors are supposed to have a fair background in thermodynamics (and also electricity) these handbooks frequently entail a section of reminders of these energy related topics

bull energy checks checklists or walk-through guides - associated with energy audit models of the scanning type these supporting documents are developed in order to facilitate the work of the auditor assuring at the same time both quality and rapidity of the survey They are primarily intended for energy auditors but can also be used as self auditing tools for those energy managers in industrial premises who intend to start an energy management process by themselves before requiring external assistance

bull calculation methods and software - another core component of energy audit schemes are calculation methods and software which are associated to energy audit models of the analysing type Their primary objective is to help the auditor in the quantitative assessment of energy saving potentials and evaluation of investment costs and paybacks The use (by an auditor) of a recommended or certified calculation tool (provided it is used correctly) is a certainty for quality results quality for the audited client

bull data collection form(s) - generally associated to the calculation tool for which they constitute the input data this type of support document helps the auditor in collecting all the necessary information for the survey It will be part of the final report and will also contribute to facilitating the follow-up of the site energy features and the interpretation of the audit results and recommendations

bull report templates - as for data collection forms report templates are also frequently associated with the calculation tool of which the output results must be integrated in the report The report is the deliverable of the audit proposing a template helps all the participants to make the most profitable use of the audit service and produce good quality audit reports

bull checklist for quality control of audit reports ndash this checklist is a document which can be used at both company level and at auditor level (self-check) it is a complement or an alternative to report templates and a practical translation of energy audit models what is specified in the energy audit model as expected results should be in the report and the checklist is an easy way to verify that the work has thus been done according to the specifications

bull building ratings target values or benchmarking - key figures can be used either as marketing information to spark off the need for energy audits they are also used by the auditors as technical data to justify their recommendations in the case of simplified audits and can even contribute to detailed audits in checking calculations or replacing data difficult to meter or evaluate either way

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72 Version April 2006 SSEIPPCBENE_Draft_1

bull databases on energy conservation options (ECOs) - one difficult part of the audit is having detailed information on costs and consequences of energy saving recommendations A database of ECOs encompassing this information will save a lot of time and money for the auditorcompany and thus help lower the cost of the audits with a maintained quality Keeping the data up-to-date requires quite a lot of work

Many of these tools may overlap and it is the responsibility of the company to determine what is necessary to use The above-mentioned tools are in general not specific of a target sector or an energy audit model but their usefulness frequently corresponds to one or several phases of the audit survey

322 Energy monitoring [55 Best practice programme 1998] [56 Best practice programme 1996] [98 Sitny 2006] Energy monitoring is the predominant activity within energy management to use and interpret energy use information The objective of monitoring is to get reliable and traceable information on the issues which influence energy efficiency (eg energy flows press-levels) Energy monitoring is a practical tool used for demonstrating that energy efficiency objectives set in energy programme for a whole company are implemented and achieved To achieve those objectives some sub-objectives or targets are set in the monitoring system Also eg material flows can be incorporated in the monitoring system Monitoring is at the heart of any strategic approach to energy management If there is no special energy management system the monitoring must be linked to other management systems Monitoring enforces the principle that energy should be viewed as a production cost rather than an overhead A monitoring system provides management information on the use of energy and other resources This information is collected by several relevant measuring points in the process and utilities and then analysed in cost accounting centres (EACs) and further at department and site level Energyenvironmental account centres are the units at the site where energy usage can be related to a production variable such as throughput The structure of the monitoring system is illustrated in Figure 38

Meters

SITELevel 1

DepartmentLevel 2

DepartmentLevel 2

Account centreLevel 3

Account centreLevel 3

Account centreLevel 3

Account centreLevel 3

Figure 38 Structure of a monitoring system [98 Sitny 2006]

This monitoring process is continued on a regular basis and the information is collected in the form of reports on performance against targets Regular reviews of these reports improve awareness of resource consumption and highlight areas where efficiency can be improved as shown in Figure 39

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SSEIPPCBENE_Draft_1 Version April 2006 73

Measure energy consumptionand production

Review performanceand action plan

Implement energysaving measure

Develop targets

Produce reports to monitor energy use

against output

Figure 39 Monitoring process [98 Sitny 2006]

The principle of this monitoring is a universal methodology and so not limited to a specific sector Therefore the approach can be used for virtually all sectors eg for the food and drink industry metal industry chemical industry buildings and transport but the degree of complexity varies An operating monitoring system consists of six major steps These are bull metering metering energy usage through a system of sub-meters to identifiable areas or

individual pieces of plants eg named as energy account centres (EACs) The most common intervals are weekly daily or shifts Monthly invoices from utilities are generally not sufficient

bull targeting determining target levels for each of the EACs by relating the energy usage to a measure of activity eg the output of the production line in a factory or outside temperature

bull analysis establishing a regular reporting system in most cases weekly that gives a performance measure for each EAC and identifies variances in terms of financial gain or loss A variance prompts an analysis maybe including further investigation and then an action

bull accountability to make people responsible is a powerful way of ensuring their commitment bull energy teams setting up energy teams that meet regularly to discuss ways of improving

performance and to carry out the actions identified In addition a regular feedback mechanism on performance to all levels of the company creates greater awareness and the motivation to improve

bull action taking action to reduce waste of energy The monitoring system reveals energy losses and all those involved must make decisions to implement the measures to improve the situation Monitoring helps to identify problems and then the correct action can be taken Action is essential for achieving savings

323 Energy models [11 Franco 2005] A very basic issue for improving energy efficiency is to know the starting point In many cases there are not proper measurements and so the information even from the use of energy is very vague To improve the situation a measurement system must be set up Usually an energy audit is needed and based on that information will be gathered

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74 Version April 2006 SSEIPPCBENE_Draft_1

Energy models are useful tools to carry out complete and in-depth energy diagnoses in whatever context (industrial service buildings) The aim of an energy diagnosis is to identify and select a number of actions that once implemented reduce the cost of the supplied energy It is possible to reach such an aim by bull rationalising important energy streams bull identifying ad-hoc energy saving technologies bull recovering waste energy streams bull optimising energy supplying contracts Each of the above goals has to be focused on two aspects one technical and the other economic however only the technical aspect is described here The technical aspect both under a theoretical andor experimental point of view concerns knowledge of productive plants and services Such knowledge has to be formalised so that it can be easily managed The first tool to fix the technical knowledge about plants is an energy model The model both electric and thermal summarises all the energy consumptions in the studied context in the form of a data sheet A reliable energy model is the primary tool one can face the energy question with It should be complete but not redundant easy to write out handy to consult useful for the heads of different departments such as energy management maintenance purchasing and accounts An energy model is based upon data collected lsquoin the fieldrsquo or after hypothesis and evaluations It is preferable if the data are collected and classified as follows bull department or production line bull utilities (compressed air pumping vacuum external lighting etc)

3231 Example 1 Electric energy models For the electric model at least the following data for each working device needing electricity such as motors and drives pumps compressors electric furnaces etc are gathered bull rated power bull rated efficiency bull load factor bull working hours per year Whereas power and efficiency are easy to detect as they are normally labelled on the device itself the load factor and the hours per year is estimated When the load factor is estimated to be greater than 50 then the load factor itself is approximately equal to

P(eff) LF= P(rated) x ŋ Equation 31

where bull LF is the load factor bull P(eff) is the estimated average electric power effectively absorbed by the device during its

working hours (kW) bull P(rated) is the rated power (kW) bull Ŋ is the rated efficiency of the device (at full load)

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SSEIPPCBENE_Draft_1 Version April 2006 75

If necessary Peff can easily be measured by some electric power meters It must be pointed out that the efficiency and the power factor of a device depend on the load factor according to Figure 310 drawn in this case for a generic motor

Efficiency

Power factor

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100Load factor ()

Figure 310 Power factor of a device depending on the load factor [11 Franco 2005]

If the single case must be handled attentively eg because of the dimensions of the machinery or its importance in the process then the auditor must calculate the real efficiency by means of a specific diagram for a specific device Once the real efficiency has been determined then this correct value should be used in Equation 31 The contect of a simple electric model is illustrated in Table 32

A B C D E F G

DEPARTMENTS DEVICES n Rated power

kW

Rated efficiency

Working hours per

year

Load factor

Energy consumed

kWh

Department 1 Device 1 10 55 092 500 1 298913

Device 2 20 4 085 4000 08 301176

Device 3 15 10 09 4000 09 600000

Total Dept1 780 1200089 175

Department 2 Device 1 1 500 085 3500 05 1029411

Device 2 20 15 09 4000 1 1333333

Device 3 5 75 08 4500 09 189844

Device 4 10 2 075 1500 08 32000

Device 5 3 150 092 3000 095 1394022

Total Dept 2 1307 3978611 581

Department Device hellip hellip hellip hellip hellip hellip

TOTALS 3250 5425000 1000

Table 32 A simple electric model lsquonrsquo in column lsquoArsquo represents the number of identical devices (under both a technical and an operating point of view) present in that department

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76 Version April 2006 SSEIPPCBENE_Draft_1

The lsquoenergy consumedrsquo in column lsquoFrsquo is given by multiplying the number of devices x rated power x working hours x load factor and dividing by rated efficiency

A x B x D x EF= C Equation 32

By adding all energies consumed in each department the total energy consumed by the entire plant can be calculated If the context studied is not so broad or complex this kind of model could be adequate to detect the areas where energy saving possibilities are most likely to be found It is sufficient to direct attention to the distribution of electricity consumptions for each department shown in column lsquoGrsquo It is very likely that a series of actions to improve energy efficiency will be found in those departments where consumption of energy is the highest while departments whose consumption is low can be neglected or taken into account later When the context deserves it (because the cycle of production is extremely complex or when energy data have never been collected before) it would also be useful to collect following data to identify energy saving actions eg bull for motors and drives

o kind of machinery driven by the motor (compressor fan pump etc) o identification code o manufacturer and model name o type of motor o installation year or residual life o number of rewinds carried out so far o type of speed control if existing o type of mechanical transmission o possibility to shift the operation to different times (to exploit more favourable electricity

tariffs at specific times or on specific days) bull for lighting apparatus

o type of lighting body o number of lamps in a body o number of lighting bodies o type of lamps o rated power of the lamp o efficiency of the lamp o kind of ballast (iron copper or high frequency)

Validation Since a good energy model is a strategic tool to carry out an energy audit it is mandatory to validate it before use The first step to validate an energy model is to compare the total amount of energy consumed as derived from calculations with the amount consumed as shown in the invoices for energy supplies If the context is very broad or complex it would be useful to compare partial amounts of energy consumed in each department with the amounts locally recorded by some automatic accounting device

Chapter 3

SSEIPPCBENE_Draft_1 Version April 2006 77

If there is not a good correspondence between the two amounts of energy (coming from the energy model and from invoices) this means that the hypothesis assumed at the beginning to draw up the energy model must be modified In particular the load factors and the working hours for the different devices must be determined with greater accuracy Another cause for non correspondence is the failure to take into account all devices really working in the plant

3232 Example 2 Thermal energy models The drawing up of a thermal energy model is more complex than an electric model To have an exact and reliable picture of the thermal consumption two kinds of models are compiled first level models and second level models To compile the first level energy model it is necessary to take a census of all users of any kind of fuel For any consumer of fuel (eg boilers furnaces etc) the following data should be recorded bull kind of fuel supplied quantity in a year bull kind of thermal carrier entering the boiler (eg pressurised water) flowrate temperature

pressure bull condensate percentage of recovery temperature pressure bull boiler body manufacturer model installation year thermal power rated efficiency

exchange surface area number of working hours in a year body temperature average load factor

bull burner manufacturer model installation year thermal power bull exhaust flowrate temperature average carbon dioxide content bull kind of thermal carrier leaving the boiler (eg steam) temperature pressure Though all previous data should be collected in the first level thermal model (lsquogeneratorsrsquo sidersquo) only a few of them must be taken into account as in the drawing of an electric model (see Table 33)

A B C D E F G

PROCESS Device n Rated power kWth

Rated efficiency

Working hours per

year

Load factor

Energy consumed Nm3 CH4

Big kilns 4 800 085 7700 08 2417000 Phase 1 (eg burning) Small

kilns 5 600 085 7700 08 2266000

Total Phase 1 6200 4683000 765

Hot water boiler 2 2500 092 1000 05 283200

Steam boiler 2 1000 092 7000 05 793200

Phase 2 (eg heat production) Hot water

boiler 2 1000 092 1600 05 181200

Total Phase 2 9000 1257600 205

Spray drier 1 400 07 200 1 11900 hellip Hot air generator 1 400 085 1600 05 39200

Small heaters 37 30 08 1600 05 115700

Phase 3 (eg Services)

Big heaters 2 60 08 1600 05 12500 30 Total Phase 3 2030 179300

TOTALS 3250 6119900 1000

Table 33 Data ina thermal energy model (generators side)

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78 Version April 2006 SSEIPPCBENE_Draft_1

In this case to make the comparison easier the energy consumed has been estimated as Nm3 of natural gas The amounts of natural gas consumed are given in this case by

A x B x D x E x 3600F= C x 34500 Equation 33

Where 1 3600 conversion factor from kWh to kJ 2 34500 is the net heating value for natural gas (kJNm3) The first level thermal model (lsquogeneratorsrsquo sidersquo) must be checked to see if the total amount of energy demand is equal to the total energy reported in the invoices for natural gas supply If so the model is reliable and useful to indicate the best areas in which to implement energy saving actions When assessing the thermal use of energy second level models (lsquousersrsquo sidersquo) are also required to be built To draw up such data sheets it is necessary to take a census of all machineries needing thermal energy in any form (hot water steam hot air etc) except fuel (taken into account in the first level model) For every item of machinery the following data should be collected bull kind of thermal carrier needed bull hoursyear of thermal demand bull load factor at which thermal energy is used bull rated thermal power

Such data can be arranged in Table 34 as follows

A B C D E F G

DEPARTMENTS DEVICES n Thermal carrier

Thermal power kWth

Working hours

per year

Load factor

Energy request

Nm3 CH4

Department 1 Device 1 2 steam 500 1000 1 104200

Device 2 1 steam 125 500 08 5200

Device 3 5 hot water 75 5000 08 156400 Total Dept 1 265800 218

Department 2 Device 1 1 steam 75 2500 05 9800

Device 2 20 hot air 10 3000 1 62500

Device 3 5 steam 50 2500 08 52100

Device 4 10 hot water 5 1500 08 6300

Device 5 3 steam 25 3000 09 21100 Total Dept 2 151800 125

Department Device

TOTALS 1215700 1000

Table 34 Data in a thermal energy model (users side)

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SSEIPPCBENE_Draft_1 Version April 2006 79

The second level model (lsquousersrsquo sidersquo) is useful to verify the match between the heat supplied by the utilities (boilers heat generators etchellip) and the heat requested by the users In this case the amounts in column F are given by

A x C x D x E x 3600F= 34500 Equation 34

In the previous example the calculation was as follows 1257600 + 179300 = 1436900 Nm3 of natural gas supplied In the second level model the calculation shows 1215700 Nm3 of natural gas demand The 15 difference is due to the efficiencies at following steps heat generation distribution piping and regulation and final use If this difference is acceptable then the two models can be considered as lsquocertifiedrsquo in the opposite case some correction (normally to the number of working hours or the load factors) is needed to reach convergence If the difference between the two amounts is big this is due to a high level of losses in the production-distribution-use for different carriers (eg steam hot water etc) In this case different actions aiming to improve the energy efficiencies for example in the field of insulations of recovery of condensate etc are likely to be possible

3233 Energy diagnosis using the energy models A complete energy diagnosis for a given organisation can be carried out according to Figure 311

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80 Version April 2006 SSEIPPCBENE_Draft_1

1) Process analysis

2) Drawing up ofenergy models

3) Theoretical energyindicators

6) Effective energyindicators

4) Energy invoicescollection

7) Areindicators

comparable

9) Areindicators

comparable

8) Reference energyindicators

10) Detecting energysaving actions

11) Cost-benefitanalysis

12) Priority foreconomically viable

actions only13) End of diagnosis

5) Production datacollection

NO

YES

YES

NO

Figure 311 Scheme of energy diagnosis [11 Franco 2005]

Notes bull points 1) 2) 3) are the collection of energy data coming from the electric and thermal models and the

calculation of appropriate energy indicators (eg MJtonne of product kWhm2 etc) bull the same indicators must be calculated from the data of production and for energy supplies points 4)

5) 6) bull such indicators are compared (7) and if they are almost equal then the energy models can be

considered lsquocertifiedrsquo otherwise corrections have to be made to the models themselves until convergence is reached

bull the lsquocertifiedrsquo indicators have now to be compared with energy benchmarks coming from literature energy agencies scientific associations etc If this kind of indicator is still comparable then it means that the lsquoenergy behaviourrsquo of the organisation is in the mainstream average and that it will be difficult to find corrective actions

bull finally if the certified indicators are greater than the benchmarks then energy use in the organisation can be improved It is likely that some energy saving actions will be detected and once only those viable from an economic point of view have been implemented the energy indicators will converge and at this stage the diagnosis can be considered finished

Chapter 3

SSEIPPCBENE_Draft_1 Version April 2006 81

324 Pinch methodology Description of the energy efficiency technique Pinch methodology is a process integration methodology which provides several tools in order to analyse industrial processes in terms of energy saving and pollution prevention according to costbenefits assessment Pinch is a computer-based simulation tool to analyse the minimum energy targets of industrial plants The analysis will identify realistic energy saving projects The starting point is the analysis of involved streams (hot and cold) and utilities (eg fuel steam cooling water) and then the creation of composite curves Each process stream can be represented by a curve in the enthalpytemperature plot moving from the hot temperature to the cold temperature with a fixed heat capacity (CP) All the hot streams could be represented by the hot composite curve obtained by the sum of heat capacity flowrates of streams that are presents in each temperature interval The hot composite curve represents the energy accumulated in the process streams and the temperature range in which it is available Similarly all the cold streams are represented by the cold composite curve The composite curves are plotted in the same HT plot to provide information about the system (see Figure 312) these information are bull minimum process heat required from hot utilities QHmin bull minimum process heat released to cold utilities QCmin bull heat recovery

Hot composite curve

∆∆TTminmin

Cold composite curve

PINCH

QHmin

QCmin Heat recovery

H

T

Figure 312 Hot and cold streams in Pinch methodology [12 Pini 2005]

These are the energy targets for the process From this evaluation it is possible to perform a complete pinch methodology study aimed at identify how these targets could be achieved Heat recovery and integration opportunities are analysed by studying how hot material streams can heat and cold material streams cool the process flows

Chapter 3

82 Version April 2006 SSEIPPCBENE_Draft_1

One of the most important features of this procedure is the template creation The templates are Excel files where the input and output data describing the industrial processes are presented The creation of these files allows us to manipulate the data in effective way so that local operating conditions at other sites can be accurately represented For example the template created for crude distillation unit of a refinery if rightly manipulated should be suitable for describe another similar CDU Pinch methodology has usually the following steps

Steps Main features

Data acquisition PFD Process stream data Utility data

Simulation Template for providing utility and process data

Pinch methodology

Utility assesment (grand composite curve) Minimum energy consumption valuation

Saving calculation Template

Economic aspects Template

Table 35 Steps in Pinch methodology

Achieved environmental benefits especially including improvements in energy efficiency The procedure fits the energy efficiency concept well because it allows the minimum energy consumption of a plant and the subsequent potential saving to be quantified Moreover pinch methodology offers the tools to understand the way the energy savings can be obtained Quite often process industry uses from 10 to 30 extra energy compared to the best design solutions This methodology reduces energy consumption and variable cost of the unit and the CO2 emissions can be reduced to 10 ndash 30

Operational data Some results of the application of pinch methodology are shown in Figure 313 Refinery (nominal capacity is 4550000 tonnesyr) composed of following sections bull primary distillation (DP3) bull catalytic reforming (RC3) bull liquid petroleum gas (LPG) splitter bull isomerisation (ISO) bull dewaxing and hydrodesulphuration (MDDW+HF1) bull visbreaking and thermal cracking (VBampTC) bull merox unit bull sour water stripper (SW1) bull naphta splitting

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SSEIPPCBENE_Draft_1 Version April 2006 83

Olefins and aromatics production (nominal feed is 490000 tonnesyr of virgin naphtha) It is a traditional steam cracking TDI plant (118000 tonnesyr) where toluene diisocyanate is produced via phosgene Olefinic products besides ethylene are propylene cracking gasoline and residuum Aromatic products (benzene toluene dicyclopentadiene) are recovered from cracking gasoline A TDI plant (11800 tonnesyr) is where toluene diisocyanate is produced via phosgene Vinyl chloride monomer (VCM) and polyvinyl chloride (PVC) production - dychloroethane (385000 tonnesyr) is obtained by reaction between HCl ethylene and air Vinyl chloride monomer (280000 tonnesyr) forms from dychloroethane cracking VCM is polymerised in aqueous solution and then dried to produce polyvinyl chloride powder (200000 tonnesyr) Butadiene production (nominal capacity is 60000 tonnesyr) Butadiene is obtained after butanes splitting and absorption in dymethyl-formalamide studies For the VCM plant the possibility of medium pressure steam (MPS) generation has been identified This fact explains the reason why hot utility saving exceeds the 100 value For several processes there is not the chance to save on cold utilities

116 163 165261

39

205 235

008

175273

00

13

1592

000000 000 0629

979

0

Crackin

g

Butadien

e DP3

MDDW+HF1 ISO

RC3

VBampTC

GPL splitt

ingMero

x

Naphtha sp

litting

SW1VCM

PVC TDI

Hot utility saving

Cold utility saving

Figure 313 Energy savings identified by pinch methodology [51 Pini 2005]

Applicability Pinch methodology is widely used for the design of new units and for the retrofitting of existing ones It has many applications such as bull energy analysis of process units bull utility plus heat and power system analysis bull heat exchanger network design and analysis bull total site analysis to optimise process and utility integration bull hydrogen and water system analysis

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84 Version April 2006 SSEIPPCBENE_Draft_1

Pinch is a heavy and expensive tool for companies The implementation of this methodology needs a great number of data and a deep knowledge of the process For some processes eg where a single type of streams (cold or hot) exists pinch methodology is not applicable Experienced professionals are needed to implement Pinch methodology The team consists of Pinch expert process simulation experts experts to handle cost estimations and plant operation experts to comment on the results PC computer and Pinch software are needed

Cross-media effects bull increasing process throughout by eliminating energy bottlenecks

Economics bull implementing study costs are dependent on the size of the analysis starting from

EUR 100000 per case Implemented energy saving cases covers non-investment operational changes and process modification investments which typically have a short payback time In grass root cases Pinch can reduce investment costs

Driving force for implementation Economic savings and environmental benefits are the reasons for using Pinch methodology

Example plants

bull Neste Oil in Finland Porvoo and Naantali refineries (wwwnesteoilcom) bull Borealis Polymers Oy Finland (wwwborealisgroupcom)

Reference information [117 Linnhoff March ] [118 KBC ] [119 Neste Jacobs Oy ] [12 Pini 2005] [51 Pini 2005] [67 Marttila 2005]

325 Benchmarking Description of the energy efficiency technique Benchmarking is simply said to be lsquoimproving ourselves by learning from othersrsquo but can also be defined- eg in following ways bull lsquobenchmarking is about making comparisons with other companys and then learning the

lessons which those companies each show uprsquo (The European Benchmarking Code of Conduct)

bull lsquobenchmarking is the practice of being humble enough to admit that someone else is better at something and being wise enough to learn how to be as good as them and even betterrsquo (American Productivity and Quality Center)