Pumped hydro storage: technology overview and methods for the evaluation of new pumping plants applied to the case study of Tirso 1 and Tirso 2 in Sardinia

Nowadays, with the climate change challenge and the goals to decarbonize our industries, starting from the energy sector, the subject of energy storage is more important than ever. The electrification of the final uses will mean an increase in the request of electric energy, but a more intermittent power supply, mainly from solar (scale utility and solar rooftop) and wind (onshore and offshore), will create a more challenging environment for the grid managing, stability and for the predictability of the production. Pumped hydro can offer a serious and competitive option when considering utility scale storage. The objectives of this thesis are to give an overview of the state of the art for the hydroelectric storage, talking about its strengths and weaknesses, always having in mind economic and environmental considerations, and its future, particularly in Italy. And thinking about how to correctly use the limited water resource so that all the stakeholders can be considered when making decisions, so all the services shall be considered. After an overview of the technology, the thesis will focus on a real case study of Tirso 1 and Tirso 2 in Sardinia, where there is an opportunity to evaluate the feasibility of a pumped storage plant. The PHS would work in parallel to Tirso 1. The goal here is to study the case and understand its critical aspects. One of the aspects presented in this thesis, is the importance of revamping or repowering older hydropower power plants, older dams, so to reduce the civil works and costs behind these capital-intensive projects, since it is difficult to find suitable sites and that, at least in Europe, there is not a lot of appetite for large new hydropower power plant. Clearly pumped hydro storage is not "the one solution" but, it is part of a wide range of technologies, necessary to achieve the stated long-term climate goals.