Combined heat and power (CHP) is an efficient and clean approach to generating electric power and useful thermal energy from a single fuel source. CHP is used either to replace or supplement conventional separate heat and power (SHP). Instead of purchasing electricity from the local utility and burning fuel in an on-site furnace or boiler to produce thermal energy, an industrial or commercial facility can use CHP to provide both energy services in one energy-efficient step.
Every CHP application involves the recovery of otherwise-wasted thermal energy to produce useful thermal energy or electricity. CHP can be configured either as a topping or bottoming cycle.
In a typical topping cycle system, fuel is combusted in a prime mover such as a gas turbine or reciprocating engine to generate electricity. Energy normally lost in the prime mover’s hot exhaust and cooling systems is instead recovered to provide heat for industrial processes (such as petroleum refining or food processing), hot water (e.g., for laundry or dishwashing), or for space heating, cooling, and dehumidification.
In a bottoming cycle system, also referred to as “waste heat recovery,” fuel is combusted to provide thermal input to a furnace or other industrial process and heat rejected from the process is then used for electricity production.
Why is CHP more efficient than conventional electricity generation?
CHP is a form of distributed generation, which is located at or near the energy-consuming facility, whereas conventional generation takes place in large centrally-located power plants. CHP’s higher efficiency comes from recovering the heat normally lost in power generation or industrial processes to provide heating or cooling on site, or to generate additional electricity. CHP’s inherent higher efficiency and elimination of transmission and distribution losses from the central power plant results in reduced primary energy use and lower greenhouse gas (GHG) emissions.
What are the benefits of CHP for the energy user?
CHP reduces energy costs for the user.
CHP reduces the risk of electric grid disruptions and enhances energy reliability for the user. This is particularly useful for hospitals, research institutions, or industrial facilities where electric power outages are particularly disruptive and costly.
CHP provides predictability in the face of uncertain electricity prices.