Expressed in simple terms, cogeneration (or combined heat and power) refers to a form of heating that simultaneously produces electricity, or vice versa, a power plant that simultaneously supplies heat. In this way, consumers are supplied with the two most important forms of energy: electricity and heat. The heat that is produced during electricity generation can be used for the preparation of hot water and steam, or for drying purposes. This means that the utilisation rate for the fuel is between 90 and 95 percent.
In combination with electric heat pumps, the broad use of cogeneration plants represents a great deal of potential: it would be possible to reduce primary energy, and the associated CO2 emissions for room heating and hot water production, by around 50%. This reduction is equivalent to 25% of the entire level of CO2 emissions in Switzerland. On top of this it would also be possible to produce around 30% of the country's electricity from cogeneration plants.
By 2010, cogeneration plants could reach an installed capacity of 1,530 MW, and thus generate 5.5 billion kWh of electricity and 10 billion kWh of heat.
Cogeneration plants normally take the form of block-type thermal power plants that consist of a combustion motor and a generator. The utilised waste heat is obtained from the motor cooler and exhaust. In combined gas and steam plants, electricity is produced twice: both by the gas turbine and from the steam from the gas turbine's waste heat boiler. Fuel cells are also a form of cogeneration in that they use an electrochemical process to produce electricity and heat from hydrogen and oxygen.
The indirect support measures of the federal government focus on wood and other forms of biomass as energy source, and increased use of cogeneration involving sewage treatment plants, as well as additional electricity production in waste incineration plants.