In the building heating/cooling sector, it is often difficult to resort to the use of renewable energy because there is significant seasonal deviation between periods of higher energy demand compared to those of higher thermal energy supply. In order to effectively address this seasonal misalignment, one of the possible solutions is to resort to seasonal storage systems. In this context, the use of underground thermal storage systems, ATES systems (Aquifer Thermal Energy Storage), has significant potential.

This report presents the results and the methodology adopted in order to investigate the feasibility and sustainability of ATES systems and, therefore, to promote their development nationwide. Currently, in Italy, there are no ATES projects, despite the geological characteristics being rather favorable, given the presence of extensive alluvial basins. On the Italian territory, the distribution of sedimentary basins and related surface aquifers was analyzed and, based on the geological characteristics and data availability, three sites were identified on which to proceed with accurate 3D simulations, both static and dynamic, designed to investigate temperature and pressure.

For the site known as “Areale Ravenna”, geological/modeling analyses were completed, considering different options for the industrial process of an LT-ATES (Low Temperature) system, i.e., investigating the effect of different volumes of injected and extracted water and the effect of the distance between injection and extraction wells. These analyses allowed us to define the most suitable conditions for the implementation of a potential ATES project. In the second site, known as “Areale Lombardia”, geological and fluid dynamic numerical simulations were conducted, on the assumption of an HT-ATES (High Temperature) system in which the excess heat produced by a biomass power plant was accumulated underground and subsequently extracted when necessary. For the third site, “Areale Roma”, an accurate geological/hydrogeological investigation was carried out to identify aquifers present in the subsoil of an area with a high population density and, therefore, with a potential user base of extraordinary size.

The results of the numerical simulations conducted show that the adopted methodology is suitable for this type of applications.