The increasing exploitation of electricity from Intermittent Renewable Energy Sources, such as wind and photovoltaic, causes instability in the electrical system. To mitigate the problem, it is necessary to increase storage capacity in the grid. In this regard, Terna has outlined future scenarios for the need for new storage following the directives of the Fit-for-55 climate package.

Pumped Hydro Energy Storage (PHES) plants represent significant resources, especially for southern regions. Therefore, it is necessary to develop methodologies for the sustainable localization and characterization of new PHES, using large existing reservoirs or innovative configurations exploiting the sea. This study presents an approach based on Multi-Criteria Analysis for the characterization and ranking of possible traditional and marine PHES, aimed at increasing electrical storage. The methodology was applied to the regions of Calabria, Sardinia, and Sicily, considering the storage needs outlined by Terna’s scenario.

Weights for different indicators were defined with some Italian and international stakeholders in the sector, such as hydroelectric operators, universities, and research centers. The methodology considers criteria such as availability and flexibility requirements, economic aspects, and ease of approval and implementation of plants, also taking into account the effect of overlap and proximity to restricted areas.

Thirty-one indicators of various natures were delineated, including the incidence of the siltation in traditional PHES, the effects of climate change, proximity to congested HV networks, opportunities for desalination plant installation for distressed areas, the effect of local production from renewable sources, costs and economic benefits, impacts of works during construction phase, etc.

Through the methodological application, it was possible to obtain, for each of the considered regions and for different stakeholders, the set of PHES plants necessary to ensure various hypotheses of coverage of the expected storage needs. In scenarios of mixed exploitation (traditional and marine), the demand is predominantly covered with marine plants in Calabria and Sardinia, while for Sicily, there is a tendency to cover the demand through medium-sized traditional pumping plants.

The Report is available on the Italian site