Depends on the energy. Back into electrical energy would be a waste in many cases (exceptions like cars occur). Pumps are maintenance parts and you need a a fit

Depends on the energy. Back into electrical energy would be a waste in many cases (exceptions like cars occur). Pumps are maintenance parts and you need a a fitting landscape. Batteries are a solution, but having billions of them isn't viable as well, especially not under ecological considerations. Superconducting storage are only energy efficient if you neglect the required cooling, otherwise they can only fulfill their function as a small short time buffer. I don't want advertise hydrogen, but it is the most simple form of potential energy in our atmosphere and I have the impression that fans of the accumulator feel threatened somehow. Sure, investments in hydrogen technology should not negatively affect research in batteries. But since they already have real economical applications, I don't see any issue here. There are numerous interests that would want more powerful batteries.