THEMATIC ISSUE The geothermal potential of the underground of the Salento peninsula (southern Italy) Giovanna De Filippis • Stefano Margiotta • Sergio Negri • Mauro Giudici Received: 28 August 2014 / Accepted: 30 December 2014 Ó Springer-Verlag Berlin Heidelberg 2015 Abstract The low-enthalpy geothermal energy systems exploit the underground as a heat reservoir, by coupling it with highly efficient heat pumps: in winter, the energy stored in the subsoil can be transferred to the surface to heat buildings, whereas in summer the surplus heat in buildings can be transferred back to the ground providing a cooling action. Despite the high costs for installation, low-enthalpy geothermal systems have high energy effi- ciency and, therefore, contribute to energy saving, to the use of renewable energy sources, to environmental sus- tainability (the effects on the hydrogeological cycle are often negligible) and to the reduction in fuel consumption and in gas emissions. In this paper, a simple methodology is proposed to assess the geothermal potential of the underground of the Salento peninsula (southern Italy) at the regional scale, by calculating the equivalent thermal performance of the subsoil, which expresses the thermal power that is potentially extractable and useful to heat or cool a building. Since the possibility of exploiting the underground as a heat reservoir depends on the physical properties and water saturation of rocks, previous detailed studies on the hydrostratigraphic setup of the region are the basis for this analysis of geothermal potential. The equivalent thermal performance depends on the thermal efficiencies of different lithological units, whose ranges of values, for heating only, are provided in literature. For this case study, a stochastic approach has been applied: several combinations of thermal efficiencies were ran- domly selected from the intervals of reference values for every hydrostratigraphic formation and the corresponding minimum depths below the ground surface that must be reached to get the desired equivalent thermal performance are computed. The results show that the underground of the Salento peninsula has great potentialities for heating of buildings, except for some coastal areas because the saltwater intrusion phenomenon could cause problems for the realization of low-enthalpy geothermal energy systems. Keywords Low-enthalpy geothermal energy  Equivalent thermal performance  Aquifer  Salento Introduction In response to an increased global demand for energy and to the growing environmental concerns over fossil fuel consumption and CO 2 emissions (DECC 2009, 2011), there have been mounting efforts to save energy by employing more energy-efficient technologies, such as geothermal energy, for both electricity generation and heat. Geother- mal energy has the capacity to contribute large amounts of base-load energy and to guarantee a safe and distributed energy supply, which is independent from imports of mineral or hydrocarbon resources, requires only small G. De Filippis (&)  M. Giudici Consorzio Interuniversitario Nazionale per la Fisica della Atmosfere e delle Idrosfere (CINFAI), Tolentino, MC, Italy e-mail: giovanna.defilippis@unimi.it G. De Filippis  M. Giudici Dipartimento di Scienze della Terra ‘‘A. Desio’’, Universita ` degli Studi di Milano, Milan, Italy S. Margiotta  S. Negri Laboratorio di Idrogeofisica e Stratigrafia per i Rischi Naturali, DISTeBa, Universita ` del Salento, Lecce, Italy S. Margiotta  S. Negri Geomodsrl-Dipartimento di Scienze dei Materiali, Spin-off of Universita ` del Salento, Lecce, Italy 123 Environ Earth Sci DOI 10.1007/s12665-014-4011-1