The benefit of using dynamic rather than static heat assessment methods early in a mine water energy project

Mine water geothermal (MWG) heating offers a low-carbon solution for space heating, helping reduce greenhouse gas emissions. To assess the feasibility of an MWG scheme, an estimate of extractable heat is required to size the system, to determine if it meets surface demand, and evaluate economic viability. In early project stages, where data are limited, static methods, such as geothermal heat flow, mine water volume, rock volume, and flow rate, are commonly used. However, these methods do not account for mine geometry. GEMSToolbox is a streamlined dynamic model, purpose built for MWG, that operates with the same limited data as static methods but also incorporates digitised mine plans. It allows rapid modelling of scenarios such as roadway collapse and shaft treatments, and helps identify optimal injection and abstraction points. We apply GEMSToolbox to a digitised two-seam coal mine and to a simplified synthetic grid model of similar size. The resulting dynamic heat estimates are compared with those from static methods, revealing order of magnitude differences, from 4,200 MWh to 210,000 MWh over 40 years. Using dynamic modelling early in project development improves targeting of exploration wells, enables site-specific mitigation planning, and reduces uncertainty. GEMSToolbox offers a practical alternative to static methods, enhancing both technical confidence and investment readiness in MWG projects.