An interdisciplinary approach to designing

sustainable bio-energy systems

Jonathan D. Nixon Sustainable environment research group

Introduction

The interdisciplinary use of engineering (design analysis,

experimentation and simulation) and management (decision science

and economic modelling) philosophies to advance sustainable energy

systems.

Case examples

- Hybrid solar-biomass power plants

- Energy recovery from municipal solid waste

Content

Hybrid solar-biomass systems

Multi-Criteria Decision-Making methods

- Technology selection

- Product development

Status of municipal solid waste and energy services in India

- Options for energy recovery from MSW in India

A hybrid solar-biomass power plant

Solar

Thermal

Field

Biomass

Boiler

Steam

Turbine

Absorption

Chiller

Electrical

Ice

Reject Heat

The sun’s

rays are

captured in

a solar field

to generate

steam

Biomass is burnt to

supplement the solar

field at night and

during cloudy days

Through the use of a

steam turbine and

chiller, electricity,

heat and ice are

produced

Solar thermal technologies

Research questions

What is the appropriate technology?

Can we improve the design?

Is a hybrid plant feasible?

With the increasing complexity of sustainable energy systems, so

does managing all the required decisions.

System failures are often down to the inappropriate selection of

technologies, suppliers, capacities, etc.

Andasol 1 – Andalusia

Solar thermal technologies. Continued

Plataforma Solar de Almeria

MASDAR City

Multiple criteria

Technical

Pressure tolerance

Temperature tolerance

Chemical compatibility

Reliability

Availability

Optical efficiency

Collector efficiency

Concentration ratio

Economic

Capital costs

O&M costs

Environmental

Land usage

Slope tolerance

Water usage

Scalability

Technology selection

Structured multi-criteria decision-making techniques such as the

Analytical Hierarchy Process (AHP) provide a holistic approach to

analysing complex decisions.

Uses quantitative (site visits and literature reviews) and qualitative

data (interviews with stakeholders/experts) to make a selection

The linear Fresnel reflector technology was indicated as the preferred

solar thermal collector for generating electricity in India.

Technology development

Working in Gujarat, India on linear Fresnel reflector prototypes

Cost-exergy optimisation of linear Fresnel reflectors to maximise

power output, operational hours and minimise costs

Receiver

Mirror elements

Solar Rays

Tower

AHP

results

WHATs /

Customer

Requirements

Competitive

Assessment/

Final

Overall

Weighting

Relationship Matrix

Technical Priority

HOWS / Technical Requirements

Deg

ree of Im

po

rtance

Pugh selection matrix

Concept selection

Novel technologies

Technology applications

Best application of a hybrid plant depends on the design priorities of a

plant

Electricity generation

Tri-generation

Process heat

Decision making techniques can be applied to optimise trade-offs –

plant efficiency, levelized unit energy costs, payback periods, energy

security and biomass saving.

Hybrid plant comparison with biomass-only

Hybridization increased levelised costs by 2-5 ¢/kWh.

Reduced biomass and land usage by 14–29%.

For the hybrid plant case studies it was observed that a 1.2 – 3.2

times cost increase in biomass would have resulted in comparable

levelised energy costs with biomass-only operation.

• In 1996 rice husk cost 4–20 $/tonne

• In 2011 cost 30–60 $/tonne

• The printing factory (case 6) reports that

their bio-bricks have increased from 16 to

100 $/tonne in the last 6 years

Municipal solid waste in India

India produces 100 million tonnes per annum of solid waste

- 70 % collection efficiency

- 90 % of which goes to unsatisfactory landfill

400 million people without access to electricity in India

Waste facilities in the UK

Incinerators, recycling and landfill in the UK

Technologies used in Europe may not be

suitable for India

Options for energy recovery from MSW in India

Comparison of options for energy recovery from MSW in India

Technical

Energy

Content

Net Output

Parasitic Loads

Pre-Treatment

Environmental

Emissions

Volume

Reduction

Risk

Establishment

Retention

Time

Financial

Capital cost

Generation

cost

O&M

Alternatives

Landfill, Anaerobic Digestion, Incineration, Pelletisation and Gasification

Social

Visual

impact

Noise

pollution

The Analytical Network Process

The ANP structure helps to identify all relevant criteria, facilitate the development of

criteria weightings and incorporate dependencies between criteria attributes.

Technical

Energy Content

Net Output

Parasitic Loads

Pre-Treatment

Environmental

Emissions

Volume

Reduction

Risk

Establishment

Retention Time

Financial

Capital cost

Generation

cost

O&M

Alternatives

Landfill

AD

Incineration

Pelletisation

Gasification

The ANP results

A combination of AD and gasification for electricity generation from

MSW should be the focus for municipalities, policymakers,

entrepreneurs, investors and plant developers in India.

Pelletisation and landfill with gas recovery are considered to be

unfavourable for managing MSW in India.

There is a potential for modern-day state-of-the-art incineration

plants in India.

Conclusions

The effective utilisation of multi-criteria decision-making tools is

becoming increasingly important to manage the growing complexity

of sustainable energy systems.

They have enabled better and more informed recommendations to

be made on alternative technologies for generating energy in India.

The AHP and ANP methodologies can be adopted by decision

makers in the worldwide energy sector to minimise risk and ensure

sustainability in project planning

Thank you for your attention

Jonathan D. Nixon