3.1.1. Pumped Hydro Storage (PHS)

Pumped hydro storage power plants provide for more than 95% of the world's current electrical storage capacity [18]. In pumped hydro storage systems, two water reservoirs at different heights are utilized to pump water during off-peak hours (charging), and as needed, water flows downstream from the top pool to the lower reservoir, driving a turbine that produces electricity (discharging). The efficiency of the PHS plant ranges from 70% to 85% [19]. The main benefits of this system are long life and almost unlimited cycle stability, while its drawbacks are its topography and heavy land use. The world's largest PHS plants have installed capacity of 3003 MW and 2400 MW (as of December 2021), respectively.
