[retrac]

The fields do not interact in that way. When you move a normal electromagnet through a magnetic field, the electromagnet's field is affected because the the other magnet induces a current in the conductor. Possibly a counter-current, lessening the total magnetic field of the electromagnet.

That kind of induction doesn't happen in a superconductor. That's the Meissner effect - a superconductor rejects the induction of currents by exterior magnetic fields. I don't really understand the physics but, I think, the zero resistance is a property of a state of matter able to transfer electrons without electrons actually being involved. It's immune to normal electromagnetic effects.

Practically speaking, when you charge up an inductor made out of a superconductor, and then connect the two ends together -- the current cycles endlessly and the coil holds the magnetic field. It behaves like a permanent magnet you can turn on and off.

If you were to then apply a load to the terminals and break the loop, the energy held in the magnetic field will flow back out of the inductor as electricity.

It's already a thing, practically. Such systems have been built to load balance spiky transmission lines, etc. They fit into a unique niche somewhere between capacitors and batteries in trade-offs.

[peteradio]

So you've not explained how this can be used as storage. Just because the conduction is free does not mean that the field interactions don't induce a load...

[retrac]

There is no induction, so there is no load.

Consider: why does a permanent magnet stay magnetized even in a changing magnetic field? Why do two permanent magnets stay magnetized when you bring them together and apart again?

When you move through the magnetic field of a permanent magnet, no energy is drawn out from the permanent magnet. All of the work occurred externally. It's the same with an energized superconducting electromagnet. Its field will not be "stripped away" by interacting with magnetic objects. The flux might be reduced if you brought an opposing magnetic flux near it -- but it would be increased again when you moved it back away. Net zero work.