Combined
heat and
power: The
recovery of heat (a
waste product of
electrical generation) which is then put back to use for
heating,
cooling, or more electrical generation (e.g. the waste heat from a gas
turbine used to create
steam, which can power another turbine). Useful for increased efficiency of
onsite power generation.
In the Middle Ages, excess heat from cooking fires was captured to turn roasting spits, and Edison's Pearl Street station piped steam to Drexel Morgan to warm the offices of his potential investors....While a conventional gas turbine squanders two thirds of its energy input into the atmosphere, cogeneration can result in a total energy efficiency of 70 percent or higher, and cuts CO2 emissions in half.
--Steve Silberman, "The Energy Web," Wired, 9.07, p. 119