cogeneration, in power systems, use of steam for both power generation and heating. High-temperature, high-pressure steam from a boiler and superheater first passes through a turbine to produce power (see steam engine). It then exhausts at a temperature and pressure suitable for heating purposes, instead of being expanded in the turbine to the lowest possible pressure and then discharged to the condenser, which would result in losing energy remaining in the steam. Steam discharged from the turbine at the medium pressure in cogeneration can provide large amounts of lower-temperature energy for such applications as heating buildings or processing food products. Considerable overall energy savings can be obtained by cogeneration.