Cogeneration  through combined heat and power is the simultaneous production of electricity, generation of mechanical energy with the recovery and utilisation of heat.

While the mechanical energy is converted directly into electricity, the heat can be used to heat, cool or generate steam. The heat resulting from the electricity generation therefore does not simply escape into the atmosphere unused, but is put to good use.

Trigeneration or combined cooling, heat and power (CCHP), is the process by which some of the heat produced by a cogeneration plant is used to generate chilled water for air conditioning or refrigeration. An absorption chiller is linked to the combined heat and power (CHP) to provide this functionality.

Both natural gas and various forms of Biogas are commonly used. For power users where security of supply is an important factor for their selection of power production equipment CHP and CCHP are ideally suited as captive power plants (power plants located at site of use).