Drilling into mines for heat: geological synthesis of the UK Geoenergy Observatory in Glasgow and implications for mine water heat resources

Thermal energy from groundwater in abandoned, flooded, coal mines has the potential to make a significant contribution decarbonization of heat and net-zero carbon emissions. In Glasgow, UK, subsurface observatory been constructed for mine water storage research. We synthesize geological resource findings 4 year period borehole planning, drilling, logging testing. The heterogeneous bedrock is typical Scottish Coal Measures Group, whereas superficial deposits are more sand- gravel-dominated than predicted. Mine boreholes encountered workings Glasgow Upper, Ell Main seams, proving water-filled voids, waste, fractured rock mass intact pillars, with high yields on initial hydrogeological Although depth extent delineated abandonment plans proved accurate, metre-scale variability was expected boreholes. A reservoir classification established highlights areas total extraction, stowage, stoop room workings. Because their spatial extensive across UK shafts or roadways, increasing evidence base reducing exploration risk these types legacy important. Supplementary material: Borehole reports other datasets available at https://ukgeos.ac.uk/data-downloads (mixture over 20 DOI data packs published openly https://nora.nerc.ac.uk ; all material deposited National Geoscience Data Centre).