Cogeneration is a prinzip of an effizient and dezentral energy supply, which can be realised by different technologies. The increase of the capacity of combined heat and power (CHP) plants is a very promising option of the reduction of CO2-emissions. Otherwise the possible increase of CHP-systems was prevented by the massive reduction of the prices of electricity, which was causally connected by the liberation of the energy market. New developments in technology and a better general set-up should help to double the share of electricity power production of the CHP-plants up to 2010.