Are we ready to make the next-generation of geothermal systems profitable in low-temperature crystalline cratons?
Crystalline cratons are the oldest and most stable geological regions on Earth, covering large parts of Northern Europe, North America, China, and Russia. Historically seen as unsuitable for geothermal development due to low natural permeability and modest heat flow, these regions are now being reconsidered thanks to technological advances. Building on methods traditionally used in the oil and gas industry, our research compiles geological, fluid flow, and petrophysical data from multiple outcrops and boreholes across Finland, reexamining the geothermal potential of its crystalline bedrock and offering insights for global geothermal resource exploration in crystalline cratons. Our research found that, similar to geothermal systems in the Rhine Graben (Central Europe) and Cornwall (UK), large crustal faults significantly enhance reservoir properties in crystalline rocks. Along these faults, porosity exceeds 30% and permeability can reach up to 1.5 × 10⁻¹¹ m², controlled largely by brittle deformation and mineral alteration. These processes improve heat transfer and well performance. Cross-flow tests indicate hydraulic conductivities above 10⁻⁵ m/s and lateral connectivity exceeding 1000 meters, suggesting that doublet geothermal systems along faults could achieve high flow rates. Our numerical models predict that a 3 km-deep Enhanced Geothermal System (EGS) within these reservoirs could deliver a steady thermal output of around 3 MW for over 50 years production period. Additionally, mineral alteration mobilizes critical elements like lithium and hydrogen, offering potential for co-production of these valuable elements. In our preliminary economic assessment, EGS exploiting fault zones and hybrid geothermal systems emerge as promising and feasible solutions for large-scale heat storage and production. Our findings demonstrate the feasibility of geothermal development in stable crystalline terrains, providing a blueprint for diversifying global renewable energy resources.
Short bio: Alan Bischoff is an energy geoscientist with over 15 years of experience in both industry and academia. His research focuses on advancing geoenergy technologies for the energy transition, including geothermal resources, carbon sequestration, and natural hydrogen. He specializes in fault-related crystalline reservoirs and Enhanced Geothermal Systems for megawatt-scale energy production in cratonic regions. Alan uses advanced rock imaging techniques to assess subsurface properties and resource potential. His career includes roles at Petrobrás, the University of Canterbury, and the Geological Survey of Finland. He is currently an Associate Professor at the University of Turku, Finland, and leads GeoEnergEx (geoenergex.com), providing expertise in geoenergy exploration and development.
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