ANNEX VII

1. 1 ANNEX VII A COMPARISON OF DISTRIBUTED CHP/DH WITH LARGE SCALE CHP/DH Paul Woods Oliver Riley Parsons Brinckerhoff Ltd

2. 2 Objectives of Study

3. 3 Scenarios The heat and power demands of the buildings within a generic city could be met by: A – City-wide DH system supplied by a single large CCGT power station at the city edge B – 10 separate District level DH systems supplied by smaller CCGT power plants C – 50 Local DH systems supplied from spark-ignition gas-engine CHP D – individual Building CHP systems using spark-ignition gas-engines for apartment blocks and Stirling engines for individual houses (circa 100,000 units) Balance of electricity demand/supply by trading on national grid

4. 4 Scenarios

5. 5 Factors influencing the outcome CHP unit type and size CHP unit utilisation CHP unit performance characteristics CHP capital and operational costs Extent and design of required DH infrastructure DH capital and operational costs Energy transmission losses Cost of fuel Value of electricity

6. 6 ‘Generic’ city derived from European data

7. 7 Modelling – energy demand assessment

8. 8 Modelling – CHP performance characteristics

9. 9 CHP Simulation Model

10. 10 Energy balance results – heat supply

11. 11 Energy balance results – electricity supply

12. 12 Environmental results summary

13. 13 Economic results summary

14. 14 Conclusions City-Wide CHP (400MWe CCGT) Most economical on a large scale – lifecycle efficiency savings offset capital cost of city-wide DH infrastructure Delivers greatest environmental benefits Potential for incorporating alternative heat production sources i.e. energy from waste, biomass, fuel cells Requires high degree of regulation to sanction necessary infrastructure works and ensure high levels of take-up

15. 15 Conclusions District CHP (70MWe CCGT) Delivers environmental and lifecycle cost savings over other CHP scenarios except City-wide scheme In Outer City cannot compete economically with alternative scenario (gas boilers) Potential for incorporating alternative heat production sources i.e. energy from waste, biomass, fuel cells Requires high degree of regulation to sanction necessary infrastructure works and ensure high levels of take-up

16. 16 Conclusions Local CHP (circa 5MWe SIGE) Not cost effective generally but more competitive in Inner City Largest part of the DH infrastructure cost is at Local level SIGE not as good environmentally as CCGT due to lower efficiency and lower proportion of CHP heat supplied Less regulation required than for larger schemes as only a few ‘anchor’ customers need commit initially Local environmental impact must be minimised with careful design

17. 17 Conclusions Building CHP (15kWe Stirling to 2MWe SIGE) Avoids DH infrastructure costs and minimises losses because energy is consumed near to the source of production Low electrical efficiency More economical than Local CHP in low density Outer City areas Potential costs to upgrade electricity network if high penetration of distributed generation is to be achieved Potentially higher electrical efficiency in future with fuel cells