Combined heat and power, or CHP, is the concurrent production of useful thermal energy (heating and/or cooling) and electricity or mechanical power from a single source of energy. Most commonly electricity is generated first in the process, with the waste heat captured to create useful thermal energy. This is also called cogeneration. Other applications use fuel directly to create thermal energy for a process, and then use the waste heat to create electricity and/or mechanical power.
Because CHP creates multiple forms of useful energy using a single source, it is a highly efficient process often operating at 65-75% efficiency.
Multiple technologies can be used in CHP applications including reciprocating engines, gas turbines, microturbines, fuel cells, and steam turbines. Fuels that can be used include natural gas, liquid fuels such as diesel or fuel oil, solid fuels such as coal or biomass, and hydrogen. Common applications for CHP include industrial and commercial facilities with significant heating loads and district heating systems.
CHP may also be used in multi-family residential buildings and, in some limited cases, in individual residential homes. As of the end of 2018, the U.S. Department of Energy Combined Heat and Power Installation Database reported 4,545 CHP installations in the U.S. with a total generating capacity of 81,094 MW.