CHP is a combination of technologies designed to deliver power and heat. The fuel source utilised in the combustion process determines whether it is classified as renewable or low carbon. Gas engine CHP can accommodate low-carbon natural gas, renewable fuels such as biogas, biomethane, syngas, sewage gas, and hydrogen, for when it becomes commercially available. Other CHP technologies can accommodate solid biomass and liquid biofuels.
Within the UK and Ireland most CHP plants are based on gas engine primemovers which are fuelled by low carbon natural gas, biogas and biomethane. According to the latest statistics published by the Digest of UK Energy Statistics (DUKES), in 2020 natural gas remains the main fuel consumed by CHP schemes representing 72% - up from 69% in 2019, with renewables accounting for the next highest share at 15%. Fossil fuels other than gas now account for just 7.5%.
Biomethane, also known as renewable natural gas, is produced from biogas that is derived from organic matter such as food waste, wastewater sludge, animal manure, or agricultural waste. As part of the biogas upgradation process, CO2 and other contaminants are removed to produce a renewable fuel.
Users looking to fuel their CHP plants using biomethane can apply via the Green Gas Certification Scheme (GGCS) – a subsidiary set up by the Renewable Energy Association to ensure and trace biomethane, or ‘green gas’, through the supply chain to certify its origin for users that buy it.
In this way the GGCS eliminates double counting of registered green gas within the supply chain to ensure the biomethane contracted has been procured from registered and accredited biomethane producers.
Each kWh of biomethane is electronically tagged with a unique identifier known as a Renewable Gas Guarantee of Origin (RGGO). This identifier contains, for each kWh of gas, information about where, when, and how it was produced. When consumers buy green gas the RGGO is their guarantee that the gas is authentic and has not been sold to any-one else.
According to the UK Hydrogen Strategy policy paper published 17th August 2021, it is understood the UK government will prioritise hydrogen application for transport, large energy users and heat.
Below is an excerpt from the document (page 57) outlining its potential within CHP plants:
Initially, hydrogen will likely be used to fuel indirect heating technologies such as steam boilers and CHP units. Given the range of sectors that use steam as part of an industrial process, our analysis indicates that boilers and CHPs could make up around two thirds of demand for hydrogen fuel switching by 2030. We will therefore focus on policies to unlock the fuel switch potential for these technologies, taking into account replacement cycles of existing equipment. Work is ongoing to establish the role of hydrogen in decarbonising CHPs.
How hydrogen develops as an energy source within the UK is unclear and will take many years to come to commercialisation. However, initiatives are taking place to develop:
The outcome from these initiatives will help shape the direction of the evolving hydrogen market. CHP is well placed to not only provide a viable technology during the transition phase to green energy but also when the transition is complete.
Equipment manufacturers have taken the challenge to adapt their technology to operate on hydrogen/natural gas mix and 100% hydrogen, which ensures that investments in CHP technology are secure.
Today, operational CHP plant can accept hydrogen blends of up to 25% within the current gas network. With a 25% hydrogen fuel blend, a further 7% reduction in CO2 can be achieved.
Learn more about Commercial Combined Heat and Power (CHP) Systems
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