Incidentally, the only viable gravity batteries known today are pumped hydro reservoirs. On the up side, they only need a hill. On the down side, they need a hi

Incidentally, the only viable gravity batteries known today are pumped hydro reservoirs. On the up side, they only need a hill. On the down side, they need a hill. (Gravity Vault, BTW, is 100% scam.) Suspending weights from ocean platforms (e.g. scrapped supertankers), for flat places with deep sea nearby, should be a viable alternative, but it has not been done yet. Deep cave systems are another, either draining water into them or (for those below the water table) pumping air in. There are a lot of deep caves.