Solar- and wind-dominated grids need abundant long-duration storage, and off-river pumped hydro offers enormous potential, with 800,000 sites worldwide and storage capacity vastly exceeding global requirements. Pumped hydro is mature, low-cost, long-lived, and locally deployable, complementing batteries by providing economical deep storage for periods of low wind and solar generation.
We need a plenty of long-duration rechargeable storage in solar- and wind- dominated electricity grids for night-time, and to ride through cloudy and windless days and weeks. Fortunately, there is unlimited off-river pumped hydro: 800,000 sites around the world with 86 million GWh of combined storage which is enough to absorb nearly 3 years of global electricity production.
Pumped hydro is highly mature, with more than 100 years of operating experience, and widely deployed, with over 200 GW of capacity. It has low water use because water is recycled in a closed loop, requires no mining, uses less land than equivalent batteries, and has high local content, unlike batteries, which are largely imported. No new dams on rivers are required. Its capital cost per kWh is substantially lower than that of equivalent batteries, and its lifespan is much longer, at up to 150 years.
