Mine water heat is a form of low-temperature geothermal energy. Abandoned coal mines fill with groundwater, which is warmed by the surrounding rock and stays at a steady temperature all year. That warmth can be extracted and used to heat homes and other buildings. In Great Britain the public body that manages the legacy of coal mining, the Mining Remediation Authority, leads most of the work on it.
How it works
Mine water is typically 10 to 20°C, and can reach about 40°C at depths of around 1km. That is too cool to heat homes directly, so the water passes through heat exchangers and a heat pump raises the temperature before the heat is sent round a heat network. Because the source does not get colder in winter, as outdoor air does, the heat pump can run efficiently all year. The cooled water is returned underground or treated and discharged.
Many schemes reuse water that is already being pumped out of old workings to protect rivers and drinking water supplies, so the heat is a by-product of work that has to happen anyway.
UK schemes
| Scheme | Status | Details |
|---|---|---|
| Gateshead | Live since 29 March 2023 | Largest in Great Britain; 6 MW heat pump, over 5km of pipes, 350 council homes plus a college, arts centre and offices |
| Lindsay, Carmarthenshire | Live since March 2025 | Heats an industrial unit using heat exchangers in a treatment pond |
| Seaham Garden Village, County Durham | Fully operational, announced 6 October 2026 | Around 750 homes, with capacity for up to 1,500 |
The authority estimates that about a quarter of homes and businesses in Great Britain sit above former coal mines. It is also testing whether mine workings can store heat, not just supply it.
Read more: Seaham mine water heat network goes live for 750 new homes.