Limits to Superconductor Energy Storage?

[John Morrell]

I'm just starting to learn about the physics behind Faraday's laws and magnetic flux and it's gotten me thinking a lot about superconductors. I know that you can store energy in a superconductor in the form of magnetic fields since a current in a superconducting loop will persist indefinitely. What are the drawbacks to this? I assume there must be some fairly low ceiling for how much energy we can store in them, or else their utility would more than make up for the inconvenience of keeping them cool...

 

[Khashishi]

There's a critical current at which a material will cease to behave as a superconductor.
See http://www.open.edu/openlearn/science-maths-technology/engineering-and-technology/engineering/superconductivity/content-section-2.5

 

[f95toli]

Superconductors ARE used for energy storage; so-called SMES systems have been used commercially for a few years. The systems are very efficient but costly and are therefore mainly used for power conditioning; i.e. to avoid "brown outs"

The amount of energy you can store is limited by the critical current and the size of the superconducting coil; the former is a property of the material used and the latter is basically limited by geometry, there is a practical upper limited to the size because you need quite a lot of structural support in order to balance the forces created because of the magnetic field within the coil and at the same time you need to avoid exceeding the critical field of the material .

 

[Khashishi]

The strong magnetic fields generated by the currents would probably be impractical for home use.

 

[John Morrell]

I thought that at first as well but after researching a bit I saw that by making the loops toroids, the external magnetic fields can be pretty small.

 

[rootone]

I thought that at first as well but after researching a bit I saw that by making the loops toroids, the external magnetic fields can be pretty small.

but the arrangements for cooling extreme electromagents with liquid helium will not be small.

 

[f95toli]

but the arrangements for cooling extreme electromagents with liquid helium will not be small.

Most modern systems do not use liquid helium; they use pulse-tubes or some other type of coolers which only require electricity (although they are quite noisy). Liquid helium is used less and less even in research labs because of the cost.

That said, all systems of this type are too expensive and too complicated for home use. The main advantage of these systems is how rapidly they can response and you do not need that for a normal home; normal batteries would make more sense for a house.