Superhot Rock Methodology Report

The report establishes a methodology for mapping superhot rock (SHR) geothermal resources globally, defining SHR as heat from subsurface formations exceeding 374°C. Using the LithoRef18 global reference model and a 'hydrothermal proxy' to account for non-steady-state heat flow, the study estimates the un-risked global resource. For depths of 4-8 km ('today's resource'), the estimated potential is 3,272 GWe (13,895 GWth). For depths of 8-12.5 km ('tomorrow's resource'), the potential increases to 59,930 GWe (245,581 GWth). The analysis identifies 125 countries with SHR potential, with significant resources in the US, China, Indonesia, and others. The report also analyzes flow rate uncertainties using a database of 33 petrothermal projects, determining a P50 flow rate of 55 l/s for its calculations.

• The study estimates the un-risked global SHR resource at depths of 4-8 km (accessible with current technology) to be 3,272 GWe or 13,895 GWth.
• The un-risked global SHR resource at depths of 8-12.5 km (a medium-term 'stretch goal') is estimated at 59,930 GWe or 245,581 GWth.
• SHR potential was observed in 125 countries globally. At depths of 4-8 km, 46 countries have potential endowments greater than 50 GWe; at 8-12.5 km, this number increases to 86 countries.
• The methodology utilizes the LithoRef18 global reference model to calculate the depth to the steady-state 450°C conductive isotherm, applying a +5km correction to account for optimistic interpretations of convective and advective processes.
• To account for non-steady-state heat flow, the report uses a 'hydrothermal proxy' map created by calculating the difference between measured surface heat flow (from the IHFC database or Lucazeau 2019 model) and the LithoRef18 modelled heat flow, selecting areas with a residual anomaly greater than +40 mW/m².
• The 'Area Developable' method was used to estimate the prospective endowment, which assumes that only 1% of the mapped shallow heat is initially developable due to factors like surface/subsurface rights and infrastructure distance.
• Analysis of 33 petrothermal projects revealed that only 47% were commercially successful (excluding research projects), with a success rate of 46% specifically for hard-rock/crystalline basement projects.
• Probabilistic modelling of flow rates for petrothermal projects established a P50 flow rate of 55 l/s, with a P90 of 25 l/s and a P10 of 100 l/s.
• The report suggests that if approximately 25% of the global prospective SHR resource at the 4-12.5 km interval were developed, it could meet the entire predicted global electric demand for 2050.

APA

Ball, P. J., Montgomery, M., & Seligman, A. (2025). Superhot Rock Methodology Report. Clean Air Task Force. https://cdn.catf.us/wp-content/uploads/2025/06/25170717/shr-heat-mapping-methodology.pdf

Chicago

Ball, Philip J., Mikenna Montgomery, and Angela Seligman. Superhot Rock Methodology Report. Clean Air Task Force, 2025. https://cdn.catf.us/wp-content/uploads/2025/06/25170717/shr-heat-mapping-methodology.pdf.

Wikipedia

{{cite report |last1=Ball |first1=Philip J. |last2=Montgomery |first2=Mikenna |last3=Seligman |first3=Angela |title=Superhot Rock Methodology Report |publisher=Clean Air Task Force |date=May 2025 |url=https://cdn.catf.us/wp-content/uploads/2025/06/25170717/shr-heat-mapping-methodology.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{ball2025superhot, author = {Ball, Philip J. and Montgomery, Mikenna and Seligman, Angela}, title = {{Superhot Rock Methodology Report}}, institution = {Clean Air Task Force}, year = {2025}, month = may, url = {https://cdn.catf.us/wp-content/uploads/2025/06/25170717/shr-heat-mapping-methodology.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }