Mapping the geothermal DHC systems maturity across the EU

This article proposes and applies a novel methodological framework for assessing geothermal market maturity in Europe, focusing on geothermal district heating and cooling (geoDHC) systems. Drawing on real-world case studies from the SAPHEA project and the COST Geothermal DHC network, the study constructs two composite indicators-Technical Maturity and Public Support-based on regulatory data, deployment characteristics, and national policy frameworks. These indicators position each geoDHC case within a Geothermal Market Maturity Matrix, visualizing how technical capability and institutional readiness co-evolve. The model is supported by GIS mapping, enabling geographic interpretation of regulatory and technical maturity. Our findings reveal significant variation across EU countries in the alignment between technological readiness and institutional support. While some cases demonstrate high scores on both axes-suggesting strong scalability potential-others show mismatches that constrain deployment despite technical feasibility. The methodology highlights policy, permitting, and infrastructure gaps that hinder innovation uptake. The combined maturity framework thus serves as a diagnostic tool for guiding policy interventions, investment prioritization, and harmonization efforts across the EU. By focusing specifically on geoDHC systems rather than national geothermal sectors, the study offers a targeted, policy-relevant contribution that addresses a key gap in the renewable energy transition literature.