Julian Hunt, Edward Byers, Yoshihide Wada, Simon Parkinson, David Gernaat, Simon Langan, Detlef P. van Vuuren, Keywan Riahi

The risk of seasonal mismatches between electricity supply and demand is increasing due to expanded use of wind, solar and hydropower resources. Power system planners are thus in search of low-cost seasonal energy storage options. Seasonal Pumped-Storage (SPS) can provide short, medium and long-term energy storage at a relatively low-cost and provides co-benefits in the form of freshwater storage capacity. Here, we present the first global assessment of SPS potential, using a novel plant-siting methodology and high-resolution topographical and hydrological data. Our results show that SPS costs vary from 0.007 to 0.2 $/m3 of water stored, 1.8 to 50 $/MWh of energy stored and 0.37 to 0.6 $/GW of installed power generation capacity. The estimated world energy storage capacity below a cost of 50 $/MWh is 17.3 PWh, approximately 79% of the world electricity consumption in 2017.