To facilitate the increasing penetration of non-programmable renewable sources into the power system, it is necessary to address the problem of load balancing and frequency regulation, as well as to have increasing shares of flexible reserve generation. Hydroelectric plants, and in particular Pumped Hydro Energy Storage (PHES) plants, in which Italy has a long tradition, are particularly useful for this purpose.

Current international conjectures and the urgency of pushing towards an increasingly sustainable development of electricity generation have led to changes in market prices that have changed the way PHESs are used. Indeed, they are now being asked to make greater contributions in providing grid services, and the implementation of new units has also become important. To this end, a GIS methodology for locating and characterizing potential PHES serving the power grid has been proposed and applied to the entire Italian territory in this activity.

This methodology has been refined and extended from RSE’s previous experience in this regard. Algorithms have been implemented to identify potential areas suitable for new realizations and to define their characteristics, both with regard to “traditional” pumping plants (existing reservoir with the construction of a new one) and with regard to marine pumping plants (new reservoir close to the coast with a lower reservoir built by the sea).

This last plant configuration is very interesting in Italy, considering the coastal extension of several kilometers where it is possible to identify several suitable areas for the realization of marine pumping reservoirs at high altitudes. The results show a large marine pumping potential of about 65.6 GW, with 255 technically possible configurations. With reference to conventional pumping facilities, the problem of siltation of existing invaders was also considered.

In order to characterize future PHES from the point of view of possible functional reduction, the degree of present and future siltation was calculated by applying the RUSLE model together with seasonal variations in the reservoir level. An initial screening of 574 analyzed reservoirs resulted in 56 technically suitable potential pumping plants. The total capacity is found to be about 13.6 GW, of which 5.1 GW is located in Sardinia, with 16 potential plants.