There are lots of grid scale battery companies, A123 was one, that were (still are?) Building giant battery packs into shipping containers as a way to store and

There are lots of grid scale battery companies, A123 was one, that were (still are?) Building giant battery packs into shipping containers as a way to store and deliver energy to the power grid during high/low cycles. One could conceive of just using those and loading and unloading them just like standard containers on a ship.