The objective of the activity is to evaluate the potential and, in particular, the applicability in Italy of two innovative closed-loop geothermal technologies:Eavor Loopsystems andWellBore Heat eXchangers(WBHX).

For both technologies, there is no need for a traditional geothermal reservoir, instead wells are used in which a process fluid heats up without coming into direct contact with deep geological formations (heat exchange). Therefore, the proposed technologies can help to increase national geothermal producibility.

The approach to the analysis of Eavor technology began in the previous three-year research period, considering the first available technology configurations. Compared to previous versions, the new Eavor Deep configuration, illustrated in the paper, can reach greater depths of up to 7 km. Like the previous configurations, it can be used in sedimentary rocks (sandstones or carbonates) and, additionally, in crystalline and metamorphic rocks.

Having established the operational range of the technology, both for thermal and electrical production, the analysis began in 2022 with the results of geothermal zoning of Italy produced during the three-year period 2019-2021. Two additional regions were identified on which to focus the analysis: Sardinia and Campania. In Sardinia, two areas with thermal anomalies were detected: the Anglona and Campidano areas, where 130°C is reached at a depth of 2000 m. The geological-geothermal analyses carried out in Campania identified the potential geothermal producibility for the region, considering as inputs temperatures of 140°C within a depth of 5000 m: 157 municipalities were highlighted, falling in some sectors of the provinces of Salerno, Benevento, and Naples, for a total geothermal potential of about 1000 MWt.

As far as wellbore heat exchangers are concerned, the analyses confirmed the possibility of reusing existing oil wells on the national territory: 842 wells were found to be potentially suitable (mainly concentrated in Lombardy, Emilia-Romagna, Marche, Abruzzo, Molise, Basilicata and Sicily). In addition, the Mazzara-Lippone concession in Sicily was chosen as a case study for assessing geothermal potential.