In theory. Turns lout building pumped hydro is really hard. Finding suitable locations is a big challenge https://www.youtube.com/watch?v=JSgd-QhLHRI&ab_channel=RealE...

Neat, but we need thousands of Hoover dam's, including the lake at the top and bottom, to store enough energy just for the US. Or to put it a different way, imagine completely draining lake Superior in just two weeks, and then over the next two weeks completely refilling it.

I'm not saying it isn't neat, but it doesn't scale to as much storage as we need.

I read about a similar idea using abandoned mine shafts.

https://www.theengineer.co.uk/abandoned-mine-shafts-energy-s...

oh I've heard about that one too actually - don't they suspend a large weight and use its potential energy as storage?

I'm a sucker for these back-to-basics engineering projects. High tech batteries be damned, let's just use potential energy for storage!

There is a German company suggesting to cut a large piece of rock (think: hundreds of meters in diameter and depth) lose and lift that by pumping water beneath it. A moving mountain, it would be. Totally crazy stuff, I should check if that ever made any progress.

Here is a German article about it. As far as I remember, the real issue is that pumps/generators with the required powers are very expensive. https://www.ingenieur.de/technik/fachbereiche/energie/lageen...

Omega Tau Podcast had a great episode about this company and project:

https://omegataupodcast.net/299-gravity-storage/

I did not know that yet, thanks for pointing it out!