The Italian geothermal play-typing, a blueprint for unlocking national geothermal development

Italy has a long history of geothermal use, but a comprehensive, updated national assessment has been lacking. This study is the first to systematically evaluate geothermal systems across Italy using the modern geothermal play concept. The primary objective is to provide a standardized, transparent, and reproducible basis for comparing geothermal systems within Italy and across European geological settings. The assessment combines geological, tectonic, geothermal, and utilization data within a GIS framework to map geothermal play types, distinguishing convection- and conduction-dominated systems. Twenty-seven plays are identified and grouped into six main types: volcanic, plutonic, and extensional domains as convection-dominated play types, and foreland basins, orogenic belt, and basement rock provinces as conduction-dominated play types. They form the first geothermal play type map for Italy. From these, 17 key play reservoirs were analyzed using borehole temperature data, lithostratigraphy, reservoir geometries, and petrophysical parameters derived from published literature. Geothermal potential of key play reservoirs was estimated through volumetric methods for Heat in Place (HIP) and, where possible, Heat Storage Potential (HSP) for medium- and high-temperature Aquifer Thermal Energy Storage (ATES). Probabilistic Monte Carlo simulations addressed uncertainties. Results highlight the exceptionally high geothermal potential of traditional, convection-dominated, plutonic systems in Tuscany, where all power plants are currently operating. In parallel, conduction-dominated sedimentary basins—especially within the Po Plain—exhibit significant potential for direct heat use and thermal energy storage, supported by large reservoir volumes and favorable petrophysical properties. Given the broad distribution of this play type across Italy, geothermal systems in Italy have significant potential that extends well beyond traditional magmatic areas. The proposed national framework provides a robust basis for geothermal energy planning, supports cross-border comparison within Europe, and identifies priority targets for future exploration, direct heat utilization, and large-scale subsurface thermal energy storage.