Yes, I agree superconducting-ring-as-battery isn't very practical at all. I was shocked by how little it can store. I was picturing that it could just become like a super super massive power line and store as much as you want, electrons are small, are they not going to fit? I thought any number of electrons will fit pretty much, it'll just keep increasing the current racing through it (not saying my EE training is the best), which I thought would be a lot. I didn't know there is a heavy magnetic component that is the limiting factor of all this. In some ways I guess it is still a lot of storage, but it isn't useful for anything. Still cool.