Cogeneration or combined heat and power ( CHP) is the use of a heat engine Cogeneration and Cogeneration Schematic, www.clarke-energy.com, retrieved 26.11.11 or power station to simultaneously generate electricity and useful heat. Trigeneration or combined cooling, heat and power ( CCHP) refers to the simultaneous generation of electricity and useful heating and cooling from the combustion of a fuel or a solar heat collector. A plant producing electricity, heat and cold is called a trigeneration or poly..