Cliff's Notes: any currently-considered form of gravity storage that isn't pumped hydro is orders of magnitude more expensive and more stupid than a Tesla Megapack.
Michael Barnard's abrasive tone aside, is he wrong?
Fengning Pumped Storage Power Station stores 40 GWh and cost 2 billion or 20 Wh/USD
Tesla megapack 2 stores 3.8 Mwh = Costs 1.5 million, or approximately 2.6 Wh/USD
It seems like pumped hydro is about an order of magnitude cheaper.
https://en.wikipedia.org/wiki/Fengning_Pumped_Storage_Power_...
Contrary to what skeptics say, there are countless locations all over. [2]
There is a suitable location 3 times larger than the Chinese one I linked That could use California's sites reservoir [1] under construction as a lower basin. It would have a similar 400m head, and an upper reservoir with 3 times the capacity or 120 GWh.
https://en.wikipedia.org/wiki/Sites_Reservoir
https://re100.anu.edu.au/#share=g-e5955e35f1c7f3677ac265bcdd...
another: https://maps.nrel.gov/psh
For small capacities, using water as the ballast medium would certainly be cheaper. But there's a break-even point in capacity beyond which the cost for readying the volume for water would be higher than the premium you'd have to pay for handling dry mass instead of liquid.
> The alternative idea is to put a lot of sand on a single elevator with huge winches that just goes up and down in a big, deep mine shaft. This one at least has the potential to be viable.
I don't think it's viable either FYI. Just pointing out your rebuke acknowledges the feasibility.
