Brief reminder that the predominate means of energy storage is literally pumping water up a mountain to flood a valley. On the surface, it's equally zany sounding, but of course the massive storage potential there is the big selling point.
Pumped Hydro energy storage is the #1 energy storage in America, and probably the world. A single plant provides 24GW-hrs of energy storage, dozens of more energy storage than all American utility scale Li-Ion batteries combined.
Bath County is the biggest pumped-hydro battery in the USA (and probably the world), but there are dozens of pumped-hydro plants across the country.
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Turns out that all the water in a lake can hold a huge amount of potential energy through gravity: just pump it up a mountain.
Actual mechanical pumping.