Geothermal ranking of Italian territory Original Research Article

The geothermal ranking of Italian territory to 3 km depth proposed in this paper is based on qualitative assessments of: 1. (1) the hydrogeological characteristics of the different rock complexes (including litho-stratigraphic sequence and structural setting), in order to identify major regional aquifers within a depth of 3 km. Clastic aquifers have not been considered in this study;2. (2) the temperature range within the regional aquifers, and the impermeable rock complexes, based on available temperature, heat-flow data and geodynamic and structural conditions. Figures 1 and 2, and Plates 1–6, illustrate the different geothermal situations in Italy in terms of geodynamic, hydrogeological and thermal conditions to a maximum depth of 3 km. Italian territory has been divided into four main categories, A–D (in decreasing order of geothermal interest), each category being subdivided into classes, according to the estimated maximum temperature of the regional aquifer or of the impermeable formations within the reference depth, and according to the different potential use of the geothermal resource. The geothermal ranking of Italy shown in Plate 6 summarizes the objectives and limits of this work, and represents a reference base for identifying the priority areas for more detailed local studies and exploratory drilling.