Is the TVA grid Racoon Mountain pumped storage facility that stores the surplus generated by the Sequoyah Nuclear plant a battery?
That's not what I was talking about. I was talking about storing electricity as electricity, not converting it to another kind of energy (i.e. potential energy of mass at a higher altitude).
Is pumped water storage worth it? I don't know. I'd have to see the specs, like how much water (mass) we're talking about and high up it is above the turbines (head), how much kWh is used to pump it up there, and how much water evaporates and has to be replaced.