Also, pumped-storage plants are massively big and expensive projects. E.g. the pumped-storage plant near my home town [1] (which I think was the biggest in Europe for a while) took two decades from planning to running [2].

[1] https://www.google.com/maps/@50.514101,12.8731705,3067m/data...

[2] https://en.wikipedia.org/wiki/Markersbach_Pumped_Storage_Pow...