lpetrich
Contributor
It's rather easy to calculate how much energy density gravity gives. For 100 meters, that's about 1 joule/gram, so I concede the low density. But one can use materials and mechanisms that are very cheap per unit mass, so the two may cancel out.
Gravel costs about $10 - $50 per ton, giving $10 - $50 per megajoule over 100 meters. By comparison, a lithium-ion battery may cost about $36 per megajoule.
But the cost of gravity storage is not just that of the lifted material. To get an idea of the cost of the lifting mechanism, I checked out CraneTrader.com | New & Used Crane And Lifting Equipment For Sale - I found several thousand dollars per ton per hundred meters.
For gravity energy storage, one may be able to take some shortcuts, since all but the lifting will be fixed, but I doubt that it would be possible to go very far with those.
Gravel costs about $10 - $50 per ton, giving $10 - $50 per megajoule over 100 meters. By comparison, a lithium-ion battery may cost about $36 per megajoule.
But the cost of gravity storage is not just that of the lifted material. To get an idea of the cost of the lifting mechanism, I checked out CraneTrader.com | New & Used Crane And Lifting Equipment For Sale - I found several thousand dollars per ton per hundred meters.
For gravity energy storage, one may be able to take some shortcuts, since all but the lifting will be fixed, but I doubt that it would be possible to go very far with those.