combined heat and power

Combined Heat and Power (CHP), or co-generation, is the generation of heat and electricity in a single process. By recycling the heat that would otherwise be wasted a CHP installation can achieve an energy conversion of over 80%. This is significantly higher than a conventional power station where much of the waste heat is simply lost. The heat recovered can be used for a variety of purposes including industrial processes, space heating and community heating schemes. Because of the high efficiency obtained emissions of CO2 and other pollutants are significantly reduced.

A CHP system typically comprises a gas or a steam turbine to generate electricity for use on site. The waste heat in the form of steam or heat is collected and used to provide heat for space heating or for some industrial process. A CHP system can have a variety of configurations. For example, in a combined cycle CHP system the recovered heat from the gas turbine is used in a steam generator to produce high pressure steam. This steam is then passed to a steam turbine where additional power is generated. CHP systems can vary in size from micro systems (less than 100kW) to systems with an output of 100’s MW.

In the UK over half of the CHP schemes are powered with natural gas. However, renewable fuels like bio-diesel, biomass, municipal and industrial waste, sewage gases and biogas from anaerobic digestion are becoming increasingly popular as an alternative to gas.

CHP is well suited for buildings that have a high heat demand. Examples include hospitals, educational establishment, leisure centres, industrial complexes and local heating district schemes.