THE FUNDAMENTAL TRUTH ABOUT CHP:
1. CHP burns fuel ONCE to produce electricity AND useful heat SIMULTANEOUSLY
2. The Government's allocation method (1/3 heat, 2/3 electricity) is an ACCOUNTING CONVENTION
- It exists for emissions reporting and tax calculations
- It does NOT represent actual fuel division (which is impossible)
3. The REAL benefit is THERMODYNAMIC:
- CHP typically achieves 80-90% overall efficiency
- Separate generation (grid + boiler) achieves ~55-60% combined efficiency
- This means ~30-40% LESS PRIMARY FUEL for the same useful energy
4. For UK CHP in 2024:
- Total fuel input: ~60,000 GWh
- Total useful output: ~49,000 GWh (electricity + heat)
- Overall efficiency: ~82%
- Primary energy saved: ~20,000 GWh compared to separate generation
- CO2 avoided: ~3-4 million tonnes annually
5. RECOMMENDATION: Present CHP benefits as:
- Overall system efficiency (heat + power / fuel input)
- Primary energy savings vs counterfactual
- Absolute fuel and CO2 reductions
- NOT as arbitrary fuel 'allocation' between outputs
This gives engineers, building owners, and policymakers the honest picture
they need to make informed decisions about distributed energy systems.