Pumped storage hydroelectric plants seem the obvious target to me https://en.m.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.m.wikipedia.org/wik

Pumped storage hydroelectric plants seem the obvious target to me https://en.m.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.m.wikipedia.org/wiki/Pumped-storage_hydroelectric...