Geospatial analysis of unconventional geothermal resources and their potential role in decarbonising heat in Great Britain

This paper presents a geospatial analysis of Great Britain's unconventional geothermal resources considering their type, quality, and distribution with respect to heat demand. The investigation builds upon past assessments of geothermal heat in the study area by analysing the available resources alongside heat demand in an integrated and quantified manner on a 10 km2 grid. By linking theoretical supply with practical demand, this work facilitates informed decision making towards increased uptake of decarbonised heat networks, which is a strategic priority for reducing emissions from UK residential buildings to net zero by 2050. To meet this goal, the market share of low or zero carbon heat networks is projected to need to rise to 20% from under 3% currently, with the present work directed at establishing the potential role of unconventional deep geothermal resources in delivering this growth. Practical resources are identified on the adopted 10 km2 grid using a multi-criteria analysis of three types of map, namely, a geological map of suitable sedimentary aquifers and granite formations, a heat flow map, and a demand map. Verification of each map is pursued by comparisons with benchmarks from the literature. It is found that 9.8% of the study area has sufficient heating demand aligned with potentially exploitable unconventional geothermal resources, comprised of 83% hot sedimentary aquifers and 17% granite formations. Implementing geothermal heat networks in this 9.8% area could decarbonise up to 27% of Great Britain's overall heat demand, representing a considerable contribution towards the net zero target. By identifying specific areas where concentrated demand aligns with available deep geothermal resources, this work further underpins decision making towards technical and economic feasibility studies at a local level.