Combined Heat and Power

Combined heat and power, also called cogeneration, is the simultaneous production of electricity and useful heat from a single fuel source, recovering the heat that a power plant would otherwise discard as waste and using it for space heating, hot water or industrial process heat, which lets a combined heat and power plant reach overall thermal efficiencies above 80 percent compared with roughly 33 to 45 percent for electricity only generation. Thomas Edison Pearl Street Station in New York, which opened in 1882 as the world first commercial power plant, already recovered its waste heat this way, achieving roughly 50 percent efficiency; the practice was common at individual factories and large buildings before centralized electric utilities took over supply through the twentieth century. The United States Congress passed the Public Utility Regulatory Policies Act in 1978 to encourage the practice, and cogeneration eventually came to supply about 8 percent of all energy used in the United States, while Finland, the world leader, met 81.8 percent of its conventional thermal electricity generation through cogeneration as of 2012. In New York City, Consolidated Edison still distributes about 66 billion kilograms of 350 degree Fahrenheit steam every year from its seven cogeneration plants, heating some 100,000 Manhattan buildings.