25% of properties in Caerphilly County Borough, Wales, are classed as having ‘Good’ opportunity for mine water heat, according to analyses by Gareth Farr and colleagues. (© Llywelyn2000, CC BY-SA 4.0, via Wikimedia Commons)
A quarter of all properties across Great Britian sit above an abandoned coalfield. The water in these flooded old coal mines could potentially be used to heat and cool local buildings. However, this low-carbon, geothermal heat source is currently underutilised, in part because it is difficult both to identify areas with the greatest potential for mine water heat and to clearly communicate that potential to policy makers and the local community.
Now Gareth Farr and colleagues at the Mining Remediation Authority, UK, report on a new approach for mapping and assessing opportunities for mine water heat recovery. Using existing data that record the depths to the mine workings and their water levels, as well as water temperature and flow, geological disturbances and the location of mine water treatment schemes, the team create a ranking system to identify promising areas. Those classified as ‘Good’, contain multiple overlapping flooded workings 30–300 metres below ground level (mBGL), with water shallower than 75 mBGL, and rising or recovered water levels. Other areas are ranked as ‘Possible’, ‘Challenging’, or ‘No opportunity’; the latter includes locations with no recorded coal mines, only shallow workings (< 30 mBGL), dry or partially dry workings, or known mine gas.
Applying this geospatial mapping approach to Caerphilly County Borough in Wales—a region with an extensive coal mining history, with workings from the 1600s to 1991—the team show that ~25% of addresses are in areas with ‘Good’ opportunity for mine water heat, with a further ~32% in areas classified as ‘Possible’. The researchers then create maps for several major cities across England, including Birmingham, Bristol, Leeds, Manchester and Newcastle, as well as all the coalfields in Wales.
The accuracy of the maps is limited by data availability, and the team is keen to stress that this approach does not remove the need for site-specific feasibility studies. However, the maps serve as high-level screening tools, sufficient to aid local planning assessments and decisions on whether to trial a pilot scheme, for example. The approach will be developed to allow greater automation, thereby enabling the rapid and unified creation of insightful, easily digestible resources that help engage stakeholders and raise awareness of the great potential for mine water heat in plans for local heat networks.
Amy Whitchurch
Details
Q. J. Eng. Geol. Hydrogeol. 59, qjegh2025-86 (2026); doi.org/10.1144/qjegh2025-086
This article is part of the Q. J. Eng. Geol. Hydrogeol. Mine Water Energy collection available at: www.lyellcollection.org/topic/collections/mine-water-energy
