The USA has enormous potential sites and water resources for pumped hydro.
I agree it’s definitely a good system to use, but that site is very wrong in thinking a few hundred sites can give these entire US a “renewable power system”.
They don’t generate any power at all. They store it. Every single Joule you get out of it, you had to put even more into it. So you need at least the equivalent amount of generation to be able to pump the water up in the first place. And that power needs to be going to prepping the tanks, not being sold. Wind and solar may be “clean”, but they have plenty of other hazards - recycling after service life, the amount of copper required for installation, the sheer land area required per Watt of generation. Not to mention maintenance and service life as well..