Does CHP have a future in a net-zero world?

By District Energy posted 08-24-2021 09:47


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In June 2019, the UK Government introduced legislation that required all greenhouse gas emissions to be reduced to net-zero by 2050. As the first major economy to do so, this was a step-change in policy that, for the first time, would enact into law the fight against climate change. While the energy supply sector has made significant reductions to its carbon emissions in recent years, it remains the second-largest contributor after transport, responsible for 21% of all emissions. Needless to say, for the UK to meet its 2050 commitment, almost all of the country’s heat and electricity demands will need to be net-zero.

CHP: Where are we?

In 2020, there were over 2,500 combined heat and power (CHP) schemes in the UK, generating 23,461 GWh of electricity and 41,696 GWh of heat. CHP schemes power hospitals, university campuses, large industrial sites and residential developments and are an important part of the UK’s energy infrastructure. However, more than 70% of all fuel burned by CHP is natural gas. CHP is an efficient conversion device of one form of energy into two, as it takes waste heat and converts it to usable heat. By generating both heat and power at the same time, CHP can reduce carbon emissions by compared to a combination of conventional power generation and a free-standing heat supply. Powering CHP plants with natural gas is, therefore, a very credible low-carbon option. But it is just that – low carbon. The 2019 legislation means that CHP schemes need to be zero carbon.

This fact has raised uncertainties around the future of CHP and has prompted the UK government to start work on a detailed consultation on its future. The real problem is the limited availability of renewable fuels. Biomass and energy from waste (EfW) both result in carbon emissions at the point of combustion. Although biomass can be a net-zero fuel as it absorbs carbon during growth, it’s relatively expensive and not readily available in the quantities necessary to meet national demand. EfW, based on municipal solid waste (MSW), is a complex fuel and difficult to burn cleanly.  Again, the available quantities of MSW are not there to meet demand at scale.

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