Seawater Pumped Hydro Storage (SWPHS), where the upper reservoir is located on the top of a steep shoreline and the lower reservoir is the sea, is more and more being considered as a viable alternative for hydro energy storage, especially for islands and coastal areas with significant density of non dispatchable renewable energy generation. In comparison with a traditional pumping station it is highlighted the actual advantage, considering the low environmental impact of the works and the great extension of sea coasts with important level gradients in the vicinity.

In the present work a case study of SWPHS is described, located in the eastern coast of Sardinia (Italy) near the village of Foxi Murdegu, with an upper seawater reservoir volume of 1.200.000 m3 and almost 370 m hydraulic head with respect to the sea level. As a first approach, a preliminary study was focused only on the hourly simulation of the Day-Ahead Italian Market (MGP), projected in the year 2020 on the basis of the expected evolution of the national and regional electric system.

The study highlighted that with MGP 2020 prices the plant would not be sustainable from the economic point of view, despite the construction costs per unit power are significantly lower compared with the other storage technologies. A new future hourly simulation was made considering scenarios to include the energy exchange with other electricity markets, namely, the balancing and the dispatching markets (MB or MSD), in order to calculate the additional needed remuneration to ensure the sustainability of the investment.