[bryanlarsen]

I didn't use the term "grid scale storage", I used the terms "short term storage" and "long term storage". Which were you asking about?

Short term storage is batteries.

I called long term storage "expensive" and implied that it's the 3rd step so into the future, so that opens up the options for nascent tech.

Note that you don't need much of a slope to do pumped hydro. For example: https://en.wikipedia.org/wiki/Ludington_Pumped_Storage_Power...