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Call for Evidence

Technological Innovations and Climate Change: Geothermal Technologies

The Environmental Audit Committee is conducting an overarching inquiry looking at technological innovations which could contribute to tackling climate change. Each part of the inquiry will look at a specific technology or strategy currently in use or in development and consider its potential and how Government policy can facilitate the UK making the best and most cost-effective use of that technology.  

This inquiry provides an opportunity to highlight UK-based examples of innovation and excellence, and the Committee is particularly keen to hear from those at the cutting edge of each sector.  

Geothermal technologies

In the current phase of the inquiry, the Committee plans to look at the potential for geothermal technologies to play a role in the UK’s journey to net zero carbon emissions by 2050.

A variety of geothermal technologies are available for the utilisation of energy stored in the Earth. These include (but are not limited to):

  • ground source heat pumps, which extract heat from a few metres below the surface to provide heat on a small scale,
  • mine energy systems, which can utilise the heat stored in the water of disused mines to provide heat on a large scale, and
  • enhanced geothermal systems, which exploit the heat formed through radioactive decays in granite deposits deep underground to provide energy for power generation[1].

The Committee examined the role of ground source heat pumps in meeting net zero goals at an earlier stage of this inquiry.[2] In the UK, it is estimated just under 44,000 ground source heat pumps are in operation— less than one-tenth of the number operating in Germany.

There are no UK mine water heating systems in operation, although the Coal Authority is currently working with a number of partners in England to develop such systems.[3] No systems delivering energy produced using enhanced geothermal systems are currently operational: some projects are in development, such as the Eden Geothermal project [4] and the United Downs Deep Geothermal Power Project [5], both in Cornwall.

The power and heat generated by geothermal technologies are generally low carbon. If the source of electricity used to drive heat pumps and water pumps is decarbonised, then the output of direct-use geothermal technologies will also be low or zero carbon. Deep geothermal technologies do emit some CO2, but these emissions are 99% lower than those from fossil fuel plants with similar generation capacities.[6] Geothermal technologies are not free from environmental concerns; these concerns include induced seismicity associated with enhanced geothermal systems [7], and negative impacts on the quality of groundwater resources.[8]

The UK Government’s Net Zero Strategy[9] and its British Energy Security Strategy[10] both set out an ambition to install 600,000 heat pumps a year (both air source and ground source) by 2028, backed by grants to help with the upfront costs of heat pumps. However, neither policy makes mention of deep geothermal as a means of providing heat or generating electricity. The Government has no current targets for the generation of either heat or power purely by geothermal means.

To date, the UK Government has not introduced a bespoke support scheme for geothermal technology projects, though there are other funding streams and mechanisms which Ministers could potentially use to support technological development and deployment. For instance, the Green Heat Network Fund could be used to fund geothermal technologies used to access thermal resources underground, as well as district heat networks which are used to deliver heat to multiple properties in an area.[11] Larger scale projects could potentially be supported through mechanisms such as Contracts for Difference[12] and Power Purchasing Agreements[13], both of which involve agreeing a strike price for the power generated by the project.

Exploiting the opportunities provided by geothermal technologies is likely to bring economic benefit to the areas involved. This could be particularly significant in post-industrial areas experiencing high levels of deprivation situated over disused mine workings.[14] For instance, the North East Local Enterprise Partnership, working with the Coal Authority, has identified 42 potential mine energy projects which, if developed, could lead to the creation of up to 15,000 jobs; it is argued that pursuing these projects would be directly beneficial to the Government’s Levelling Up agenda.[15]


Call for evidence

The Committee would like to invite submissions of written evidence addressing one or more of the following questions by 5pm on Thursday 21st July 2022:

  • What role can geothermal technologies take in the transition to net zero in the UK?
  • What barriers (technological, regulatory, or otherwise) are there to deploying operational geothermal technologies in the UK?
  • What is the scale of the potential market for geothermal energy sources and which geographic or other geological types are most suitable for exploitation of this natural resource?
  • Are current government support schemes sufficient to grow geothermal energy deployment in the U.K.?
  • What environmental concerns are associated with geothermal technologies, and are they appropriately accounted for in regulations?
  • What risks are there to investors, operators, and consumers of geothermal energy? How can these be mitigated?
  • How does the density of mine water systems affect their efficiency? Could widespread uptake of geothermal systems in dense population centres lead to a reduction in their ability to provide heat?
  • What economic impact could the deployment of mine water geothermal systems have on the areas in which they are deployed?

The Committee encourage members of underrepresented groups to submit written evidence. It aims to have diverse panels of Select Committee witnesses, and asks organisations to bear this in mind when we ask them to choose a representative. It is currently monitoring the diversity of its witnesses.

Written evidence should be submitted through the Committee’s web portal. It is recommended that all submitters familiarise themselves with the Guidance on giving evidence to a Select Committee of the House of Commons which outlines word count, format, document size, and content restrictions.


[1] Geothermal Energy, Briefing Note 46, Parliamentary Office for Science and Technology (POST), April 2022

[2] Technological Innovations and Climate Change: Heat Pumps [accessed 10 June 2022]

[3] Geothermal Energy from Abandoned Coal Mines, Coal Authority [accessed 10 June 2022]

[4] The Eden Geothermal Project, Eden Geothermal [accessed 10 June 2022]

[5] United Downs Deep Geothermal Power Project, Geothermal Engineering Ltd [accessed 10 June 2022]

[6] Geothermal Explained, Geothermal Energy and the Environment, U.S. Energy Information Administration [accessed 10 June 2022]

[7] Induced Seismicity Associated with Enhanced Geothermal Systems, Majer et. al., Geothermics, 33, 185-222, 2007

[8] Impacts of Borehole Heat Exchangers (BHEs) on Groundwater Quality: the Role of Heat-Carrier Fluid and Borehole Grouting, Bucci et. al., Environmental Earth Sciences, 77, 175, 2018

[9] Net Zero Strategy: Build Back Greener, BEIS, October 2021

[10] British Energy Security Strategy, BEIS and Prime Minister’s Office, March 2022

[11] Green Heat Network Fund – Round 1: Scheme Overview, BEIS, 2022

[12] Contracts for Difference, BEIS, 2022

[13] Introduction to Power Purchase Agreements, Crown Commercial Service, 2020

[14] The Coal Authority estimates that there are 23,000 abandoned deep coal mines around the UK, and that one quarter of the UK’s homes and businesses are sited on former coalfields: The Case for Mine Energy – Unlocking Deployment at Scale in the UK, North East Local Enterprise Partnership, 2021, p. 5

[15] The Case for Mine Energy – Unlocking Deployment at Scale in the UK, North East Local Enterprise Partnership, 2021

This call for written evidence has now closed.

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