Cogeneration is the term given to the combined production of electricity and heat. In thermal power stations, only a part of the primary energy used can be converted into electricity. The excess electricity is designated as surplus or waste heat. In conventional power stations, this waste heat has to be completely dissipated into the surrounding environment.

Through cogeneration, a large part of this energy can be used as district heating, whereby the thermal output is emitted between the turbine stages. As a result, this enables the power station to use over 90% of its entire degree of efficiency. Heat supply networks bring heat to consumers, where it can be used to heat rooms and water.

As thermal electricity production can only be produced in an energy-efficient way through expedient use of waste heat, cogeneration has subsequently become an essential part of modern energy supply in many countries.