In order to integrate large-scale renewable energy generation projects, energy storage—at both the transmission and distribution levels—is essential. A 2018 report from the U.S. Department of Energy forecasted an opportunity for 36 GW of new pumped storage capacity in the United States by 2050. Pumped-storage hydropower (PSH) is the market-leading and most established form of grid-related energy storage in the world today. Its numerous benefits versus other long-duration, grid-scale energy storage technologies include low levelized lifecycle cost.
Closed-loop PSH technology, which relies on manmade reservoirs not connected to rivers, lakes, or other natural water features, has been proposed as a way to avoid some of the siting and permitting challenges associated with traditional open-loop PSH. However, the extent to which some siting and permitting challenges can be avoided by closed-loop PSH systems might be limited by project characteristics, such as the clearing of previously undisturbed land and the need for surface or groundwater sources for initial reservoir fill and periodic water withdrawals. Although various regulatory and policy frameworks are advancing to promote the development of closed-loop PSH, there is still variability in how such projects are defined and uncertainty regarding the market and environmental sustainability of such projects relative to competing technologies.
