> than it will start sapping the electromagnetic energy from said superconductor Electromagnetic induction involves the inductor, too. With a conventional ele

> than it will start sapping the electromagnetic energy from said superconductor Electromagnetic induction involves the inductor, too. With a conventional electromagnet in a changing field, there is a current (an opposite current, in a sense) induced in the electromagnet's winding which is how the energy transfer occurs. The coil's apparent resistance increases as it moves through the field. But superconductors have no resistance :) Since a superconductor rejects induction from outside magnetic fields (Meissner effect) they do not inductively couple in the same way. Once energized and then looped, a superconducting magnet behaves more like a permanent magnet. With regard to use in power storage, strong magnets of any kind are rather inconvenient (even dangerous) around anything magnetic.