Energy from WastePlants and Energy Efficiency

Keith RileyKeith RileyManaging DirectorManaging Director

Veolia Environmental ServicesVeolia Environmental Services

“ “the definition of a recovery the definition of a recovery operation is based on the operation is based on the criterion of use and hence of criterion of use and hence of the objective of the operation.”the objective of the operation.”

European Court of Justice - 2002European Court of Justice - 2002

The European CommissionThe European Commission

Waste is recovered if:

Its combustion generates more energy than is consumed by the process itself; Most of the waste is consumed during the operation;Most the energy generated is recovered and used (either as heat or electricity);The waste replaces the use of a source of primary energy. .

Three Possible CriteriaThree Possible Criteria

Over the years three criteria had been considered by the Commission:

o The energy content of the processed waste, i.e. the calorific value - criticised because MSW has CV similar to some commonly used fuels;

o The ECJ case of principal objective - this is a subjective criterion and would require additional complex specifications;

o The energy efficiency of the plant.

2008/98/EC2008/98/ECWASTE WASTE

FRAMEWORK FRAMEWORK DIRECTIVEDIRECTIVE

WASTE FRAMEWORK WASTE FRAMEWORK DIRECTIVE 2008/98/EC DIRECTIVE 2008/98/EC

Seeks to clarify the distinction between recovery and disposal; Makes it clear that facilities whose principle purpose is the treatment of waste may be classified as recovery;

BUT…. Facilities dedicated to processing of municipal solid waste have to meet specific requirements regarding energy efficiency listed in Annex II of the WFD in order to be classified as energy recovery facilities (as opposed to disposal).

Where: Ep is annual energy produced as heat or electricity, calculated

with energy in the form of electricity being multiplied by 2.6 and heat produced for commercial use multiplied by 1.1 (GJ/year)

Ef is annual energy input to the system from fuels contributing to the production of steam (GJ/year)

Ew is the annual energy contained in the treated waste calculated using the lower net calorific value of the waste (GJ/year)

Ei means annual energy imported excluding Ew and Ef (GJ/year)

Energy efficiency Energy efficiency ηη = (Ep -( Ef + Ei)) / (0.97 x (Ew + Ef)) = (Ep -( Ef + Ei)) / (0.97 x (Ew + Ef))

Recovery or Disposal?Recovery or Disposal?

If η > 0.6 for existing plants>0.65 for plants permitted

after 31 December 2008,then Recovery

If less, then Disposal

EfficiencyEfficiency

o EfW plants are claimed to be low efficiency – 17 to 27% often quoted;

o If this is compared with the 65% required for Recovery under WFD, then at first sight it may appear unattainable without use of a high efficiency thermodynamic cycles but……

NOT ALL EFFICIENCIES ARE THE SAME!

The Statistician’s ViewThe Statistician’s View

Efficiency is a criterion by which to compare unbiased estimators. For scalar parameters, one estimator is said to be more efficient than another if the first has smaller variance. For multivariate estimators, one estimator is said to be more efficient than another if the covariance matrix of the second minus the covariance matrix of the first is a positive semidefinite matrix…………

www.about.com:Economics

The Economist’s ViewThe Economist’s View

“ Efficiency is a relationship between ends and means. When we call a situation inefficient, we are claiming that we could achieve the desired ends with less means, or that the means employed could produce more of the ends desired…. Thus, economic efficiency is measured not by the relationship between the physical quantities of ends and means, but by the relationship between the value of the ends and the value of the means.Terms such as “technical efficiency” or “objective efficiency” are meaningless. From a strictly technical or physical standpoint, every process is perfectly efficient. ………

Ref: Library of Economics & Liberty

Another DefinitionAnother Definition

Wikipedia:

η = What you get

What you pay for

Electricity generating principle Thermal Efficiency

Equivalent Carbon emission per kWh generated

Coal fired power stations 37% 985 g/kWh

Gas fired CCGT* stations 41% 640 g/kWh

50% mix of coal and gas fired generation 39% 813 g/kWh

Waste fired power station (incinerator) 27% 523 g/kWh

Coal Fired Power Station

Higher efficiency, higher Carbon emissions

ERF IncineratorLower efficiency, lower

Carbon emissions

ERF Efficiency

Let’s ask DEFRALet’s ask DEFRA

Seasonal efficiency of different boiler types o Old boiler (heavy weight) 55% o Old boiler (light weight) 65% o New boiler (non-condensing)78% o New boiler (condensing) 88%

Extract from the Boiler Efficiency Database

Boiler LossesBoiler Losses

Efficiency LimitationsEfficiency Limitations

Efficiency of a Rankine cycle is usually limited by the working fluid or the materials from which the boiler is made. This gives a theoretical of around 63% maximum.

                                                                                                                                                                                                                                                                                                    

Thanks to WFPP for use of this slide

Thanks to Afval Energie Bedrif for use of this slide

Combined Cycle

Thanks to www.global-greenhouse-warming.com for use of diagram

Sheffield Distributed Energy Scheme

o Population 525,800 Population 525,800

o 50,000 students50,000 students

o 225,000 households 225,000 households - 80% houses- 80% houses- 20% flats/maisonettes/apartments- 20% flats/maisonettes/apartments

o Generates approx. 240,000 t/yr of municipal waste Generates approx. 240,000 t/yr of municipal waste - Recycles 25% - Recycles 25% - Recovers energy from 60% - Recovers energy from 60% - Landfills 15% - Landfills 15%

o Limited landfill space availableLimited landfill space available

About Sheffield

Raising the EfficiencyRaising the Efficiency

Sheffield Distributed Energy Network

o The UK’s largest DE systemThe UK’s largest DE system

o Currently 45km of pipelineCurrently 45km of pipeline

o Water distributed by pumpsWater distributed by pumps

o Temperature up to 120°CTemperature up to 120°C

o Pressure up to 16 barPressure up to 16 bar

o Backed up by 87MW of boilersBacked up by 87MW of boilers

o Potential for further developmentPotential for further development

District Energy o Steam raised at 44 bar and 400Steam raised at 44 bar and 400˚C˚Co Condensing turbine Condensing turbine o Extraction point at 2 bar, approx 150Extraction point at 2 bar, approx 150˚C˚C

o Reduced reliance on fossil fuelsReduced reliance on fossil fuelso Improved air quality – reduced NOx emissionsImproved air quality – reduced NOx emissionso Carbon footprint 30% that of gasCarbon footprint 30% that of gas

Sheffield DE SchemeSheffield DE Scheme

Annual Electrical GenerationAnnual Electrical Generation 125,000 MWhe125,000 MWhe

Annual Thermal OutputAnnual Thermal Output 95,000 MWh95,000 MWh

Annual District Heating SalesAnnual District Heating Sales 110,000 MWh110,000 MWh

Energy per Tonne WasteEnergy per Tonne Waste 1050 kWh1050 kWh

WFD Efficiency Rating (full-year average)WFD Efficiency Rating (full-year average) 67%67%

Energy Output

Equivalent to a saving of 168 g CO2 per kWhEquivalent to a saving of 168 g CO2 per kWh

Our Customers

2 Universities2 Universities 4 Swimming Pools4 Swimming Pools 3 Theatres3 Theatres 3 Art Galleries3 Art Galleries 2 Cinemas2 Cinemas 1 Radio Station1 Radio Station 1 Greenhouse1 Greenhouse 3 Hotels3 Hotels 21 Private Developments21 Private Developments Sheffield CC HousingSheffield CC Housing Corporate BuildingsCorporate Buildings Student AccommodationStudent Accommodation

o Ambiguity - applies to MSW. What of C&I wastes?

o Ep is annual energy produced. Therefore is actual production, but is it gross or net?

o Ef is annual input from other fuels. How is the CV measured?

o Ew is annual energy of TREATED waste. What does “treated” mean? How is its LCV determined?

o Ei is annual energy imported but not used for steam production & excluding Ew & Ef. What about flu-gas recirculation?

o The energy losses are generalised & initiatives that decrease thermodynamic losses are not rewarded.

o There are unintended consequences – disadvantages hot countries, encourages large plants etc.

o BUT…..

Issues with the R1 Efficiency FormulaIssues with the R1 Efficiency Formula

The R1 formula is achievable for most moving grate plants The R1 formula is achievable for most moving grate plants above 100,000 tpa without resorting to district above 100,000 tpa without resorting to district heating/CHP.heating/CHP.

The formula is likely to become a focal point for planning The formula is likely to become a focal point for planning & permitting – developers & planners take note!& permitting – developers & planners take note!

The drive for lower carbon electricity supply will drive a The drive for lower carbon electricity supply will drive a push for increased efficiency – suppliers need to respond.push for increased efficiency – suppliers need to respond.

We must move anyway to more efficient thermal cycles, We must move anyway to more efficient thermal cycles, although some barriers need to be removed. although some barriers need to be removed.

We can do it!We can do it!