Electricity production and heat production go hand in hand. Producing electricity usually generates heat, so appliances that produce heat and power simultaneously, can reach very high levels of efficiency.
The heat they produce keeps a building warm and also provides hot water for washing and cleaning. Their electricity production can be used inside the building or fed into the electric grid. By using their fuel economically, cogeneration of heat and electricity contributes to reducing energy consumption and CO2 emissions. Even greater CO2 cuts are possible, by using green gases and fuels.
The use of heat from combined heat and power technology is particularly efficient at small scale. So-called micro-CHP and mini-CHP can be used in commercial and public buildings, apartments, individual houses and in some cases even in small collectives of houses. Several CHP technologies are available, they use engines or fuel cells. Fuel cells achieve very high energy efficiency levels and already work with 100% hydrogen.