[biggc]

Pumped storage is definitely the most efficient method of energy storage, but is it the cheapest when taking infrastructure costs and land use into account?

I remember reading about plans to use renewables to pump Colorado River water back up into Lake Mead to increase the amount of power the dam can generate during low generation periods for solar and wind.

That seems like an efficient approach, because the dam and reservoir are already there.

[missedthecue]

Up front infra costs are high but the hoover dam is nearly a hundred years old and will last another several hundred. The amortization period is very long, whereas chemical batteries will need frequent replacing.