Role of Pumped Hydroelectric Storage in Renewable Electricity Systems

In developing reliable and affordable renewable electricity systems, pumped hydroelectric storage (PHS) is a potentially effective solution for storing large-scale, low-cost energy, crucial for stabilizing the variable supply from wind and solar sources^1-⁵. To assess the potential role of PHS in 100% renewable energy system, we performed a high-resolution appraisal through a unified framework that identifies plausible open-loop PHS sites associated with coastlines, lakes, and 2.89 million rivers, as well as closed-loop PHS sites with low environmental impact. We also integrated local renewable energy resources and electricity load profiles for evaluating local energy storage needs. We find that global pumped hydroelectric storage capacity is 41.40 ± 5.47 trillion kWh, equivalent to 1.5 times the current total annual global electricity generation⁶. Combined with expanded renewable energy sources and long-distance transmission, the global pumped hydroelectric storage resources can meet the storage demands of 100% renewable energy system in 99% of the world. The assessments support developing renewable energy to achieve global electricity decarbonization.