Part Fifteen

Sustainability Speak

•   Combined Heat and Power (CHP)

• Conventional power generation is typically about 25% efficient, with most of the energy generated from burning the fuel being wasted as heat lost to the atmosphere, typically through cooling towers and flues.

• Generation of heat from boilers is a much more efficient process, with about 80% of the thermal content of the fuel being typically converted into useful heat.

• Separately, electricity and heat production are in the region of 45% efficient.

• Together, the efficiency rises to above 80%, with consequent fuel savings and reductions in harmful emissions.

• CHP, also called cogeneration, is the use of a heat engine or a power station to simultaneously generate electricity and useful heat.

• A ‘heat engine’ converts thermal energy, for example by exploiting thermodynamic ‘cycles’ (vapour to liquid, liquid to solid, solid to gas), to mechanical output.