Combined heat and power CHP
Combined heat and power (CHP), sometimes referred to as cogeneration, is a process in which the heat that is created as a by-product of power generation is captured and used rather than simply being wasted.
According to the Combined Heat and Power Association, “In today’s coal and gas fired power stations, up to two thirds of the overall energy consumed is lost in this way, often seen as a cloud of steam rising from cooling towers.”
Whilst there are a range of different forms of CHP, typically, a gas-powered turbine or reciprocating engine is used to produce electricity, and the heat recovered is used for local water or space heating, or to support an industrial process. Increasingly absorption cooling can use the heat recovered to produce cooling. Sometimes this process is referred to as trigeneration or combined cooling, heat and power (CCHP).
Alternative systems have heat generation as their primary function, and then use a steam turbine to generate electricity.
CHP as a process is not dependent on a specific fuel and so renewable fuels such as biomass feedstocks can be used.
Very broadly, CHP is appropriate in circumstances where there is a continuous local demand for heat and power, such as district heating schemes, hotels and leisure centres, industrial applications that require heat for manufacturing processes and so on. If excess electricity is generated, this can be exported back to the national grid.
The Department of Energy and Climate Change (DECC) lists the advantages of CHP as:
- An efficiency of over 80%, compared to 38% for a coal-fired power station.
- Up to 30% savings on energy bills.
- Up to 30% reduction in carbon emissions.
- Reduced transmission and distribution losses.
- Increased fuel supply security.
CHP can be a very significant investment and requires careful consideration. However, where they are certified as Good Quality (GQ) CHP, they are exempt from the Climate Change Levy for fuel inputs and electricity outputs. They may also qualify as Enhanced Capital Allowances (ECA) and be eligible for business rates exemption.
CHP plant can be manufactured as packaged units or can be custom designed and built. Increasingly, micro CHP units can be used to supply small-scale and domestic needs. In effect, these replace conventional boilers. Heat is the primary output of micro CHP, with the ratio of heat to electricity for domestic appliances typically around 6:1, generating up to 1kW of electricity. As with larger CHP plant, if excess electricity is generated, this can be exported back to the national grid. This may be eligible for Feed-in Tariffs in England and Wales and is considered an ‘eligible measure’ suitable for funding under the Green Deal.
[edit] Related articles on Designing Buildings
- Big growth in district heating markets - now and on the horizon.
- Biomass.
- Biomass CHP.
- BSRIA guide to heat interface units.
- Capital allowances.
- Can the Zeroth Energy System reduce the carbon footprint of HVAC services?
- Carbon capture and storage.
- Coefficient of Performance CoP.
- Community energy network.
- District energy.
- Fuel cell.
- Future of electricity in domestic buildings.
- Green Deal.
- Heat pump COP & EER and central plant SCOP in ambient loops.
- Heat Networks Investment Project HNIP.
- Liquefied petroleum gas (LPG).
- Low Carbon Energy Centre, London.
- Low carbon heating and cooling.
- Microgeneration.
- Micro-CHP.
- Micro-grid.
- On-site generation of heat and power.
[edit] External references
Featured articles and news
Great British Energy install solar on school and NHS sites
200 schools and 200 NHS sites to get solar systems, as first project of the newly formed government initiative.
600 million for 60,000 more skilled construction workers
Announced by Treasury ahead of the Spring Statement.
The restoration of the novelist’s birthplace in Eastwood.
Life Critical Fire Safety External Wall System LCFS EWS
Breaking down what is meant by this now often used term.
PAC report on the Remediation of Dangerous Cladding
Recommendations on workforce, transparency, support, insurance, funding, fraud and mismanagement.
New towns, expanded settlements and housing delivery
Modular inquiry asks if new towns and expanded settlements are an effective means of delivering housing.
Building Engineering Business Survey Q1 2025
Survey shows growth remains flat as skill shortages and volatile pricing persist.
Construction contract awards remain buoyant
Infrastructure up but residential struggles.
Home builders call for suspension of Building Safety Levy
HBF with over 100 home builders write to the Chancellor.
CIOB Apprentice of the Year 2024/2025
CIOB names James Monk a quantity surveyor from Cambridge as the winner.
Warm Homes Plan and existing energy bill support policies
Breaking down what existing policies are and what they do.
Treasury responds to sector submission on Warm Homes
Trade associations call on Government to make good on manifesto pledge for the upgrading of 5 million homes.
A tour through Robotic Installation Systems for Elevators, Innovation Labs, MetaCore and PORT tech.
A dynamic brand built for impact stitched into BSRIA’s building fabric.
BS 9991:2024 and the recently published CLC advisory note
Fire safety in the design, management and use of residential buildings. Code of practice.
Comments
To start a discussion about this article, click 'Add a comment' above and add your thoughts to this discussion page.