Geothermal occurrences in Sardinia - preliminary report

The Regional Government of Sardinia has sanctioned the new Piano Energetico Ambientale Regionale (Regional Energy and Environment Plan) that delineates a new strategy in the field of energy supply. This plan aims to break the energetic isolation of Sardinia, and to diversify its primary energy sources, with a consequent reduction of its dependency on petroleum. The main directrices of this strategy include: exploitation of local energy resources, by means of technologies compatible with the environment protection; seeking for and experimentation of solutions concerning energy source diversification; supplying from renewable sources; energy saving. All these aims should be reached compatibly with the necessities of a sustainable development. This also implies benefits as far as regards safety of the energy system, observance of the rules fixed by the Kyoto agreements about environment protection, as well as the principles ratified by the European Community in the subject. Research on the potentiality of exploiting the different renewable sources occurring in the territory represents an important component, in this phase of the process. In this context, geothermal energy could play a decisive role. In Sardinia, geothermal exploration through modern methodologies has commenced some 25 years ago, in the frame of the Energetic Finalized Project of the National Research Council (CNR); to this project several Universities and Research Institutes of Italy (Bari, Bologna, Cagliari, Palermo, Pisa, Sassari, and Siena) have participated. Further detail studies, especially geophysical ones, have continued up to now, especially by researchers of the University of Cagliari. All the obtained results, in the fields of geology (lithology, stratigraphy, and tectonics), hydrogeology, classic and isotope geochemistry on hot and cold springs, and geophysics (electric resistivity, gravimetry, magnetotellurics, geothermal gradient, and heat flow) all agree upon indicating that the most favourable thermal data are mostly concentrated inside the main tectonic depression of Sardinia ("Fossa Sarda"); actually most part of the obtained information concerns this sector of the island, where, furthermore, a large fraction of the local population is concentrated. Thus, a considerable potential market for a large-scale use of geothermal fluids does exist, specially as far as regards home heating, agronomy, and zootechnology; it is easily foreseen that this market will expand more and more in the time. Characterization of this georesource is the focus of our study; this work has permitted to get a reliable frame of the actual situation, both through a careful analysis of the existing literature, and through field studies