Reading Between the Seams: Assessing Heat, Interference, and Opportunity in Flooded Mine Workings

Mine water geothermal (MWG) systems can supply low-carbon heat by extracting energy from warm water in abandoned, flooded coal mines, but their wider deployment is constrained by uncertainty, including (i) where schemes are most feasible, (ii) how much heat can be sustainably extracted, and (iii) how neighbouring schemes should be managed where they share a connected mine water body. This thesis advances MWG development by improving prospectivity mapping, strengthening early-stage heat assessment, and proposing a practical basis for regulating thermal interactions between schemes.

First, emerging regional MWG prospectivity mapping methods are compared, including MiRAS, the Georesources Cornwall screening approach, the Mining Remediation Authority (MRA) opportunity mapping, and, conceptually, the more data-intensive Saxony methodology. Applied to Newcastle (UK), the methods highlight broadly similar favourable areas in but produce different spatial patterns and classifications because of divergent aims, thresholds, treatment of shallow workings, handling of mine water level data, and the inclusion, or exclusion, of heat demand.

Second, the thesis evaluates whether dynamic, mine-specific modelling adds value over common static heat-resource estimates. Using GEMSToolbox on a digitised two-seam coal mine (and an equivalent synthetic grid), results show that static methods can differ by orders of magnitude and do not capture key configuration controls (for example, shaft placement, connectivity, or collapse). Rapid scenario testing with GEMSToolbox provides time-dependent heat estimates and practical insight for feasibility-stage design and uncertainty management.

Finally, the thesis quantifies thermal interference between adjacent MWG schemes and introduces the heat extraction ratio (HER) as a simple, scheme-scale metric for expressing interference as a function of spacing, flow rate and operating lifetime. Building on international precedents and UK unitisation practice, two HER-based regulatory pathways are proposed: unitisation where feasible, or a simpler “yes/no” threshold approach. Together, these support transparent decision-making and improve investor confidence in long-term heat security.