That doesn't answer the question. What exactly is the problem that needs to be solved?

Scaling up capacity of the storage. There aren't that many sites that are geologically feasible for pumped storage (and it destroys a local ecosystem by flooding and draining it repeatedly) and batteries need rare earth metals (not actually that rare but environmentally toxic to produce).

We need O(100x) current production to fully switch away from hydrocarbons. That's a lot of reservoirs or a lot of cobalt that have to be mined.

Cobalt already eliminated from half of new Tesla batteries: https://electrek.co/2022/04/22/tesla-using-cobalt-free-lfp-b...

> batteries need rare earth metals

"Rare earths" are a column (edit: ha ha see below) in the periodic table, and are not used in batteries.

Some types of electric motors use rare earths, others do not.

Here's a primer: https://blog.ucsusa.org/josh-goldman/electric-vehicles-batte...

"Rare earths" are actually the lanthanides plus scandium and yttrium [1], not one column of the periodic table. Good information otherwise!

[1] https://en.wikipedia.org/wiki/Lanthanide#Etymology

Ha ha busted! Thanks. As an astronomer I think everything beyond He is a metal.

Globally the potential pumped storage resource is far larger than would be needed. You might be confused by assuming the pumped hydro has to be on existing rivers.

http://re100.eng.anu.edu.au/global/

False. You have been corrected on this point before. Please stop posting what you know are falsehoods.

Can't say I remember ever interacting with you before, but either way this doesn't meet the HN standards of civility/graciousness.