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
ECA Industry Awards 2024 shortlist revealed
22 leading businesses from across the electrotechnical and engineering services sector.
Government unveils Skills England strategy
Skills England to transform opportunities and drive growth.
New Government Hub for York Given Planning Green Light
For up to 2,600 civil servants, due for completion by 2028.
Construction Skills Certification Scheme cards
July update on Professionally Qualified and Academically Qualified Person Cards.
BSRIA Briefing 2024, November 22
Sustainable Futures: Redefining Retrofit for Net Zero Living.
The CLC on driving competency in the retrofit sector
Previously published roadmap on skills for net zero.
The first labour government King's speech in fifteen years
Construction industry reactions, support and some concern.
CIOB Retrofit of Buildings Technical Information Sheet
What retrofit is, the approach to be taken and processes to be followed.
Adapting Historic Buildings for Energy and Carbon Efficiency
Historic England advice note 18, free download published.
10 retrofit projects revisited 10 years after completion.
Information orders, building liability orders and SPVs
Key BSA terms and how they impact special purpose vehicles.
Listed despite problems with its design.
Zen and the art of cycling exploration.
Design Council Homes Taskforce launched
To support government 1.5 million homes target within UK climate commitments.
Comments
To start a discussion about this article, click 'Add a comment' above and add your thoughts to this discussion page.