1. General

1.1 Definitions

Cogeneration (or combined heat and power) is a system in which mechanical and thermal energy are produced simultaneously by burning a primary fuel.

The primary fuel is generally a commercial fossil fuel: coal, natural gas, LPG (liquefied petroleum gas), heavy or domestic fuel oil; it can also be wood or biomass, or a recovered product: biogas, household waste, industrial waste, by-product gases, etc. Mechanical energy, available on the shaft of the prime mover, is used to drive another rotating machine (fan, compressor) or, more frequently, an alternator that supplies electric current. Thermal energy is available either directly, or after transformation, in the form of an easily usable heat transfer fluid: steam, hot water, superheated water,...