Cogeneration of heat and power Cogeneration is the simultaneous production of electricity and useful heat. In a regular power plant, the heat produced in the generation of electricity is lost, often through the chimneys. But in a cogeneration plant it is recovered for use in homes, businesses, and industry. A trigeneration plant also produces cooling (air conditioning) as well as heat and electricity.Cogeneration plants can achieve energy efficiency levels of around 90%. Increased cogeneration could lower greenhouse gas emissions by up to 250 million tonnes by 2020.