Is electricity perpetual in a superconductor system? I wonder if electricity consumption happen according to the Law of conservation of energy and Joule effect, in a regular circuit certain amount of energy is transformed into heat by components resistance that is composed, so result in a loss of energy.
If a superconductor has no resistance, then would be a perpetual electricity stream?
 A: A superconductor can indeed carry current without dissipation. For example, in a superconducting loop you could have a current circulate essentially forever.
If by "a perpetual electricity stream" you mean you could extract perpetual work out of this current, then the answer is no. By definition, extracting work from a system means adding an effective dissipation, so as soon as you connect the current-carrying superconductor to another system on which you want to do work, the supercurrent will decay.
A: 
If a superconductor has no resistance, then would be a perpetual electricity stream?

To reach supperconductivity a lot of energy is needed for cooling, and as long as this is supplied there will be zero resistance,  the current will follow electric circuit routes.Have a look at this .

the latest issue of the journal Nano Letters, MIT researchers present a new circuit design that could make simple superconducting devices much cheaper to manufacture. And while the circuits’ speed probably wouldn’t top that of today’s chips, they could solve the problem of reading out the results of calculations performed with Josephson junctions.

