Reversible hydro is actually pretty possible in much of the world, particularly the US, because all you need is something bowl-shaped at a high elevation. Pumpe

Reversible hydro is actually pretty possible in much of the world, particularly the US, because all you need is something bowl-shaped at a high elevation. Pumped hydro for the most part needs storage measured in hours or days, and something like the size of Lake Mead behind Hoover Dam is overkill. It's also more advantageous than regular hydro, because it does not need to be in the path of flowing water, so you avoid issues with silting up, lack of suitable locations, it's much less environmentally destructive, etc.