Comment by tialaramex
14 hours ago
I can see this makes sense especially for medium term storage. A lot full of batteries is great for the next ten seconds, next ten minutes, even to some extent the next ten hours, but it surely doesn't make much sense to store ten days of electricity that way compared to just keeping the water behind a dam. We know that many of the world's large dams are capturing snow melt or other seasonal flows, running them only when solar or wind can't provide the power you need lets you make more effective use of the same resource.
Except that in many cases there's people living downstream doing agriculture using that water for irrigation. There's just this tiny dispute about that in the nile delta between Egypt and Ethiopia
https://en.wikipedia.org/wiki/Grand_Ethiopian_Renaissance_Da...
Except for very short term peaks (less than 15 minutes-ish) it doesn't make any sense at all to use hydro to charge batteries. You've got a dam, you might as well let water through later than incur the losses of a round trip to batteries and back to the grid.