There's a number of them all over the world. Surprisingly simple idea and amazingly powerful storage. https://en.wikipedia.org/wiki/List_of_pumped-storage_hydr

There's a number of them all over the world. Surprisingly simple idea and amazingly powerful storage. https://en.wikipedia.org/wiki/List_of_pumped-storage_hydroelectric_power_stations https://en.wikipedia.org/wiki/List_of_pumped-storage_hydroel...