Keywords: combined heat and power, CHP, cogeneration, production possibility sets, joint production, power-to-heat ratio, CCGT, back-pressure, extraction condensing, heat rejection, steam turbines, gas turbines, combustion engines
Quantifying Combined Heat and Power (CHP) activity
In CHP plants without heat rejection facilities power, output is complementary to the recovery of heat, and all activity is cogeneration. CHP plants with heat rejection facilities can operate a mix of cogeneration and condensing activities. Quantifying the energy flows of both activities properly requires knowledge of the design power-to-heat ratios of the CHP processes (steam and gas turbines, combustion engines). The ratios may be multiple, non-linear or extend into the virtual domain of the production possibility sets of the plants. Quantifying cogeneration in CCGT plants reveals a definition conflict but consistent solutions are available.