November 16, 2025 - Coal mines are finding a second life as companies invest in repurposing huge, disused coal sites into geothermal power projects. In the U.K., the government and energy companies have been discussing the idea for several years, and it seems to be gaining momentum with the launch of the first geothermal mine projects this year.

Energy companies have realised the potential of flooding abandoned coal mines to provide vast quantities of geothermal power, as water in coal mines can reach a temperature of up to 20 degrees Celsius. Mine water geothermal heat (MWGH) systems use the water from flooded coal mines, which is heated through a natural process, to supply clean heat to houses and businesses in the surrounding area. This works by using heat exchangers and pumps to recover the heat and distribute it to buildings via district heating networks.

Heating currently contributes around 40 percent of energy use in the U.K. The country’s building heating is a major contributor to emissions, accounting for between 17 and 18 percent of total greenhouse gases, primarily from burning natural gas. Therefore, developing cleaner heat production methods is key to decarbonising the U.K. in line with government climate targets.

A recent report suggests that around a quarter of U.K. homes sit on top of sites where MWGH could be used to provide low-cost, low-carbon heat. “With the right support in place, MWGH could be built out at scale within five years. It’s not technologically complex, relatively speaking, but it takes some governance and social organisation,” Simone Abram, the co-author of the report, explained. Abram used Denmark as an example of where the technology has already been successfully rolled out.

In addition to providing clean energy, the redevelopment of coal mines could bring energy jobs back to former mining areas, with the need for specialists in drilling, engineering, and operations. This could help reinvigorate struggling economies across the country. The authors of the report also highlight the importance of community consultation to gain support for development. Community engagement will help demonstrate how MWGH projects can bring economic growth back to disadvantaged towns and cities, as well as provide clean heating and new job opportunities.

Despite the ongoing discussion between energy companies and the U.K. government about the potential for MWGH, the U.K. has been slow to develop its first geothermal projects of this type. This is largely due to the high set-up cost and the complex regulatory environment. To support development, the U.K. government must update its energy regulations to allow companies to develop this type of geothermal project. The provision of grants and low-interest loans by the state could also help to encourage higher levels of private investment in the sector.

Earlier in the year, the Mining Remediation Authority (MRA), formerly known as the Coal Authority, launched the U.K.’s first MWGH project near Ammanford in Wales. The project uses floodwater from an abandoned mine as a renewable source of heating for a warehouse. Roughly 25 litres of water per second is pumped from the Lindsay pit each day, before being treated and filtered through natural waterways.

The MRA hopes to develop several other MWGH projects in south and north-east Wales to develop it into a geothermal energy hub. However, some projects have been hard to get off the ground due to the lack of familiarity with the energy source. For example, a similar heat scheme was halted by Bridgend council in 2021 over concerns of rising costs. However, the Welsh government has acknowledged the “significant role mine water heat can play in our journey to net zero.”

The MRA also commenced construction works in March on the Dawdon mine in County Durham, in the north of England. The MWGH project is expected to provide heating for a new housing development, a new primary school, a village centre, and innovation hubs once complete. Vital Energi has been appointed to design, build, and operate the system, which is expected to provide clean heat for the next 40 years.

The authority also launched the Gateshead Mine Water Heat Living Laboratory this year to study thermal and hydrogeological behaviour across operational MWGH projects. It is thought to be the first project of its kind globally. 

Fiona Todd from the MRA explained, “Our Living Laboratory will provide invaluable insights into the behaviour of mine water heat systems and help us understand how multiple schemes co-exist within the same region… This research is crucial for maximising the opportunity presented by mine water heat and supporting its development as a reliable, low-carbon heat source across the U.K.”

The U.K. sees significant potential in the repurposing of coal mines to develop geothermal energy projects, to provide clean heating for up to 25 percent of the country’s population. However, to accelerate the growth of the sector, the government must revise its energy regulations to simplify the framework for developing such projects. The introduction of financial incentives from the state could also help to attract more private investment to the sector.