A new open-access study by the Coal Authority titled Drilling into Coal Mine Workings: A Profile and Lessons from the UK Coalfields has powerfully debunked the myth that drilling into abandoned coal mines to utilize mine water for heating systems is inherently risky, providing strong support for the UK's goals of clean, safe, and localized energy.
The research analyzed 564 boreholes drilled across the UK and found that 87% successfully achieved their intended purposes (such as monitoring, gas venting, and water extraction). More than 75% of boreholes targeting mine voids met their objectives, confirming the predictability and feasibility of accessing mine water heat. In addition, deeper boreholes (>300m) achieved a 97% success rate, while those targeting roadways hit voids 77% of the time and achieved intended use applicability of 85%.
The study directly addresses technical and financial risk concerns surrounding the drilling of low-carbon heating, cooling, and heat storage facilities in abandoned coal mines, providing solid evidence for the wider rollout of mine water heat networks — a reliable green energy source beneath many former coalfield communities that remains largely untapped.
Lead author and Senior Hydrogeologist at the Coal Authority, Lee Wyatt, said the research shows that drilling into coal mine workings is not a high-risk activity when properly planned, designed, and executed with expert knowledge. This opens the door to investment in mine water heat networks, helping reduce heating emissions, lower energy costs, and revitalize coalfield communities.
The study supports the mission to unlock the sustainable development and energy transition potential of the UK's coalfields, boosting confidence among developers, local authorities, and infrastructure planners that mine water heat is a reliable and scalable energy source. It also complements initiatives such as the UK Geoenergy Observatories, continually improving geological understanding of mine water heat systems and their role in the energy transition
