There is some small losses, it does not run 'forever'. However the superconducting switch is pretty neat. It's a small section of superconductor between the en

There is some small losses, it does not run 'forever'. However the superconducting switch is pretty neat. It's a small section of superconductor between the ends of the coil, but is wrapped in a heating element. When the coils is first powered up the element is heated and the material has a resistance. When the coil is ready the heating element is turned off and the shorted conductor cools down and starts superconducting.