The main objective of the research project to which this document refers to is to promote a greater efficiency of the industrial sector in order to contribute to the decarbonisation process of the sector. The research also deals with the efficiency improvement of production systems based on RES. This study aims to define efficient systems applicable to geothermal energy.
The study is the result of geological-modeling analyses aimed at estimating the geothermal potential of the Italian territory and the possible application of advanced closed loop geothermal systems, with a U-shaped configuration, based on heat exchange with the subsoil as operating principle. The system does not require a traditional geothermal reservoir but involves the use of wells in which a process fluid heats up without coming into direct contact with deep geological formations. For this reason, the proposed technology is scalable and applicable to the entire national territory.
The innovation of the proposed technology consists in the methodology of construction of the closed circuit, but the designers are still investigating the methods of drilling the wells and the possibility of using alternative compounds to the classic casing, especially for the implementation of the horizontal sections of the circuits, with the aim of reducing construction costs.
In order to hypothesize a diffusion of the technology on the Italian territory, it is essential to first estimate the geothermal capability of the Italian territory, for which the volume method was used. The analysis focused on areas with temperatures equal to or higher than 120°C within 3000 m of depth, and highlighted the most promising Italian sectors in terms of geothermal energy.
Having defined the technological aspects and Italian geothermal potential, geological modeling investigations were completed for the two areas identified in 2020 in order to evaluate possible applications of the closed loop system. The sites differ in the type of rock and the presence/absence of geothermal fluids. In the first site, located in Lombardia (a region in northern Italy), there is no geothermal reservoir and the installation of the wells was hypothesized within the terrigenous formations. The second site, Castel Giorgio – Torre Alfina (central Italy), has a typical geothermal reservoir in carbonate formations with fluids at temperatures of 120°-150°C. Starting from the 3D static geological models created in 2020, several 3D numerical scenarios were simulated for both areas in order to verify the geological feasibility of the proposed systems and the effects of different configurations of the drillings in terms of length and section, as well as the influence of the fluid injection temperature.