Geothermal energy is the heat generated and stored in the ground and is a source of low-carbon, renewable energy. It is homegrown, available throughout the UK at depths from a few metres to several kilometres and can provide heat or power all year long. It is not dependent on weather conditions and can deliver baseload energy for balancing more intermittent power generation from renewable sources like solar or wind.
Geothermal technologies currently deliver less than 0.3% of the UK’s annual heat demand, using only a fraction of the estimated available geothermal heat resource. There is the potential to increase this proportion significantly and contribute to the UK’s net zero targets. However, a lack of information about the application of the technology in the UK has meant that deep geothermal is not currently factored into the UK’s carbon budget or government strategies. Roll-out may require long-term government support to develop demonstration projects and expand the industry.
Geothermal resources are broadly grouped into shallow and deep geothermal, based on the system temperatures and the technologies used for extracting the heat. Shallow systems generally require ground source heat pumps to modify the temperature obtained from the geothermal resource for use in domestic or commercial heating or cooling applications. In deep systems, the resource is at a high enough temperature to be used directly for heating or electricity generation.
The potential of geothermal energy in the UK has been investigated at various times since the 1970s when a review of geothermal resources was undertaken as part of the Geothermal Energy Programme funded by the UK Government and the European Commission. Although it identified geothermal resources across all parts of the country, the UK’s current usage is lower than that of other European countries that have similar resources.
In countries like Germany and France, geothermal energy has been shown to offer environmental, economic and technical advantages in comparison to other renewable and non-renewable heating sources. These include a small land area footprint, applications over a range of scales from individual homes to district heating scale, very low greenhouse gas emissions, and the long-term availability of the resource. Paris, for example, has been using geothermal energy for heating since 1969, today supplying geothermal heat to 250,000 households via 50 heating networks.
Geothermal energy is not recognised by law as a natural resource in the UK (like water or gas), and there is currently no bespoke regulatory system for the licensing, ownership and management of the geothermal resource. Activities are controlled under existing regulations developed for petroleum exploration or water resource use and protection. At current levels of deployment, this approach is generally regarded by regulators and industry as being adequate for managing potential environmental and operational impacts. However, some industry stakeholders regard certain aspects of this repurposed regulatory system as being over-engineered for regulating deep geothermal energy in the UK. In addition, the multi-agency set-up for deep geothermal is seen as a barrier to deployment by some as it makes the approval process complicated and time consuming. Some shallow geothermal systems are not currently regulated, but it is acknowledged by the regulator that an update of existing regulations may be required when environmental impacts of multiple systems, such as high-density urban deployments, are better understood.
Streamlining the regulatory process is seen by industry as an important measure to facilitate the wider uptake of geothermal technologies. This could take the route of assigning a single, bespoke geothermal regulator or an agency that coordinates the approval process.
Development and exploration of geothermal energy systems can have minor environmental impacts on subsurface temperatures and groundwater quality. They may also be associated with the emission of some greenhouse gases, indirectly through using non-renewable electricity for the operation of heat pumps or directly through releasing gases contained in deep geothermal fluids. Geothermal schemes, if not executed optimally, can also carry some drilling and operational risks, including induced seismicity although these would typically be of very low magnitude.
There is consensus among geothermal stakeholder groups that a ‘route to market’ is needed for the geothermal sector to develop in the UK. Building such a market framework for the different geothermal technologies could be achieved by adopting strategies similar to those provided to other renewable technologies. As evidenced by other sectors in the UK, like offshore wind, long-term government support that includes ambitious targets and subsidies could contribute to rapid cost reductions for geothermal energy systems. Stakeholders argue that the absence of long-term targets and policies that support the development of skills, supply chains and a service industry are one of the main reasons why geothermal energy in the UK has fallen behind that of other similar countries.
Upfront grants, like the new Boiler Upgrade Scheme, and subsidies like the now closed Renewable Heat Incentive are thought to be effective measures for encouraging technology adoption, but there are concerns that the current level of support and duration over which it is available is insufficient for a market to develop. While some financial support is available for geothermal power projects, there is currently no support for geothermal heating systems of more than 45 kW capacity unless developed as part of a heat network. Geothermal risk mitigation schemes are highlighted by the European Geothermal Energy Council as one of the key mechanisms for stimulating the development of deep geothermal projects, especially during stages of low market maturity. Such schemes currently do not exist in the UK.
Developing the geothermal sector could provide considerable economic stimulus and contribute to job generation, including the redeployment of both technologies and workers from the oil and gas industry who have transferable skills and experiences in risk assessment and mitigation, deep-drilling and reservoir development, and management. However, high upfront capital costs and the geological risk of not achieving the required temperatures or water flows presents a major barrier to the development of geothermal heat and power projects in the UK.
This POSTbrief was based on literature reviews and interviews with a range of stakeholders and was externally peer reviewed. POST would like to thank interviewees and peer reviewers for kindly giving up their time during the preparation of this briefing, including:
Thomas Allard, BEIS
Prof Michael Bradshaw, Warwick Business School*
Chris Davidson, Genius Energy Lab Limited
Richard Day, Eden Geothermal Ltd
John Findlay, Carbon Zero Consulting Ltd
Prof Jon Gluyas, Durham University*
Prof Helen Goodman, Durham University*
Augusta Grant, Eden Geothermal Ltd
Dr Joel Hamilton, BEIS
Rachel Hay, Climate Change Committee
Dr Melanie Jans-Singh, BEIS*
Michael Kehinde, Environment Agency*
Peter Ledingham, Geosciences Ltd*
Dr Sian Loveless, Environment Agency*
Johann MacDougall, Scottish Government
Chloé Nemo, Committee on Climate Change
Dr Christian Pletl, Stadtwerke Muenchen
Dr Jan Rosenow, Regulatory Assistance Project
Diane Steele, Environment Agency*
Prof Iain Stewart, Plymouth University
* denotes people and organisations who acted as external reviewers of the briefing