The difficulty of finding suitable sites for dams on rivers, including the associated environmental challenges, has caused many analysts to assume that pumped hydro energy storage has limited further opportunities to support variable renewable generation. Closed-loop, off-river pumped hydro energy storage overcomes many of the barriers. Small (square km) upper reservoirs are typically located in hilly country away from rivers, and water is circulated indefinitely between an upper and lower reservoir. GIS analysis of high resolution global digital elevation models was used to determine economically feasible closed-loop scheme locations outside protected and urban areas. This search identified 616,000 potential storage sites with an enormous combined storage potential of 23,000 TWh. This is two orders of magnitude more than required to support large fractions of renewable electricity, allowing flexible site selection. Importantly, the resource is widely distributed to effectively support large-scale solar and wind deployment for electrical grid decarbonization.

在河流上寻找合适的水坝地点的困难，包括相关的环境挑战，使许多分析家认为，抽水蓄能已经限制了支持可变可再生能源发电的更多机会。闭环，河外抽水蓄能技术克服了许多障碍。小型（平方千米）上层水库通常位于远离河流的丘陵地区，水在上层水库和下层水库之间无限循环。高分辨率全球数字高程模型的GIS分析用于确定保护区和城市区以外的经济可行的闭环方案位置。这项搜索确定了616,000个潜在的存储站点，这些存储站点的巨大合并潜力为23,000 TWh。这比支持大部分可再生电力所需的数量多两个数量级，从而可以灵活地选择站点。重要的是，该资源被广泛分配以有效支持大规模太阳能和风能部署以实现电网脱碳。