Geothermal-fluids-derived critical raw materials for a sustainable and independent European supply

Geothermal fluids, conventionally exploited for heat and power, represent an underutilized source of critical raw materials (CRMs) with potential to support European resource security. This review provides an integrated, European-scale assessment linking geothermal fluid characteristics with suitable CRM extraction technologies. A fluid–technology matching framework is developed to correlate brine composition, thermodynamic conditions, and geochemical evolution with process selection, with particular emphasis on membrane-based systems coupled with chemical and electrochemical operations. The novelty of this work lies in the systematic integration of geochemistry, process engineering, and techno-economic considerations into a unified evaluation framework, moving beyond prior studies focused on single elements, technologies, or isolated case studies. The analysis demonstrates that extraction performance is strongly governed by site-specific factors, including salinity, scaling behaviour, and redox dynamics, which preclude universal process solutions and instead require tailored, modular flowsheets. Quantitative estimates indicate that high-grade geothermal systems can yield CRM values of several USD·m−3, with lithium dominating the economic potential and individual installations capable of producing approximately 1−3 kt·y−1 of lithium carbonate equivalent. Economic viability is highly sensitive to flow rate, recovery efficiency, and operational costs. Environmental evidence suggests a favorable impact profile compared to conventional mining due to closed-loop operation and low-carbon energy integration, though robust and harmonized evaluations remain limited. Overall, geothermal CRM recovery represents a scalable, site-specific opportunity for European supply, provided that integrated process design, reservoir sustainability, and rigorous techno-economic and environmental assessments are addressed.