Superconductors Energy Storage

[Raider5678]

Hello everyone, the other day a friend of mine said that we should harness the power in lightning to power everything. And I quote he said "One lightning strike has enough energy in it to power my entire town forever!" Now this is high school, so obviously his thoughts on how much energy that is in a lightning bolt is greatly exaggerated, or he doesn't understand that energy gets used up in kilowatt-hours rather than simply kilowatts. Either way, I failed to mention this and said that he may be able to use a superconductor if you could get the lightning to hit it. He said ok and went on his merry way. But upon further thought when I was bored I began wondering if theres a limit on how much energy a superconductor can hold before it simply doesn't accept energy any more. Now I don't know much about electricity except the basics, and my understanding of superconductors is that they are a wire that's frictionless, so that energy could go through it forever even after the powersource is gone. I also understand that they have to be kept at extremely cold temperatures(-200 C) to retain the superconductivity trait. Now my question: Is there a limit to how much energy can go into a Superconductor before it doesn't collect it any more. And if so why that happens.

Thanks in advance!

[swansont]

There is a current density limit. For Niobium-Tin, which has the highest value, the limit is 200,000 amps/cm²

http://hyperphysics.phy-astr.gsu.edu/hbase/solids/scex2.html

 

There's no guarantee that you can easily scale up a superconductor — some are thin-film rather than bulk materials. You also would have issues with the very strong magnetic fields that these would generate, and have to worry if they would interfere with other conductors if you tried to use multiple superconductors. I don't know if this is an actual problem or not.

[Raider5678]

There is a current density limit. For Niobium-Tin, which has the highest value, the limit is 200,000 amps/cm²

http://hyperphysics.phy-astr.gsu.edu/hbase/solids/scex2.html

 

There's no guarantee that you can easily scale up a superconductor — some are thin-film rather than bulk materials. You also would have issues with the very strong magnetic fields that these would generate, and have to worry if they would interfere with other conductors if you tried to use multiple superconductors. I don't know if this is an actual problem or not.

Thanks for the reply. As for the magnetic field thing I didn't account for that. The main reason is that i was assuming that my friend could focus the lightning onto a single one rather than placing multiple in a grid lock pattern to optimize the chance of a hit, which is good thinking. Also what do you mean scale up a superconductor? Is there currently a limit to how large they have to be?

[swansont]

Also what do you mean scale up a superconductor? Is there currently a limit to how large they have to be?

 

Scale up = make them bigger to handle a greater capacity.

 

Like I said, some of them are thin-film — it only works basically on the surface. You can't make them thicker and have them work better (or possibly at all). So there may be others with size restrictions to worry about.

[Enthalpy]

Lightning delivers very little energy. Forget it.

 

Energy storage in superconductors has been prototyped by several companies.

 

Cables are made from filaments for varied reasons and have a good section. Already the magnets at the LHC store a significant energy.

 

Scaling up improves, yes. For a given current density, the achieved induction increases with the section, and even once you've reached the material's maximum induction, the energy increases as the coil volume and its density would be interesting.

 

The next question is: how good, how expensive - and there, for instance a flywheel is better, primarily because of costs.

http://www.scienceforums.net/topic/59338-flywheels-store-electricity-cheap-enough/

Don't forget neither that useable superconductors, the ones that accept a significant induction and current density, are of type II, which do have losses - in the MW range at LHC. And then, you need real cold, which is expensive. And you risk huge explosions, see "magnet quenching".

 

All put together, I don't believe it has a future, at least with present materials. But I'd be glad to be wrong.

Edited April 4, 2016 by Enthalpy

[Raider5678]

Lightning delivers very little energy. Forget it.

 

Energy storage in superconductors has been prototyped by several companies.

 

Cables are made from filaments for varied reasons and have a good section. Already the magnets at the LHC store a significant energy.

 

Scaling up improves, yes. For a given current density, the achieved induction increases with the section, and even once you've reached the material's maximum induction, the energy increases as the coil volume and its density would be interesting.

 

The next question is: how good, how expensive - and there, for instance a flywheel is better, primarily because of costs.

http://www.scienceforums.net/topic/59338-flywheels-store-electricity-cheap-enough/

Don't forget neither that useable superconductors, the ones that accept a significant induction and current density, are of type II, which do have losses - in the MW range at LHC. And then, you need real cold, which is expensive. And you risk huge explosions, see "magnet quenching".

 

All put together, I don't believe it has a future, at least with present materials. But I'd be glad to be wrong.

Alright, I understood the little energy in a lightning bolt, but what is a flywheel?

[Enthalpy]

A flywheel stores energy as the speed of a mass: 0.5*mV². To limit m, they tend to use a big V, and the flywheel's solution is to rotate the mass quickly, where the limit is the wheel's resistance to the centrifugal force.

https://en.wikipedia.org/wiki/Flywheel

 

Some people have proposed graphite composite. The strong and light material attains the highest speed but is expensive.

My proposal is strong steel, since it can be cheap http://www.scienceforums.net/topic/59338-flywheels-store-electricity-cheap-enough/

Other people have suggested concrete, with some reinforcement of undisclosed nature.

[swansont]

A flywheel stores energy as the speed of a mass: 0.5*mV². To limit m, they tend to use a big V, and the flywheel's solution is to rotate the mass quickly, where the limit is the wheel's resistance to the centrifugal force.

https://en.wikipedia.org/wiki/Flywheel

 

 

 

It's a rotational system, so the energy is 1/2 Iw², where I is the moment of inertia and w is the angular speed

[Moreno]

Hello everyone, the other day a friend of mine said that we should harness the power in lightning to power everything. And I quote he said "One lightning strike has enough energy in it to power my entire town forever!" Now this is high school, so obviously his thoughts on how much energy that is in a lightning bolt is greatly exaggerated, or he doesn't understand that energy gets used up in kilowatt-hours rather than simply kilowatts. Either way, I failed to mention this and said that he may be able to use a superconductor if you could get the lightning to hit it. He said ok and went on his merry way. But upon further thought when I was bored I began wondering if theres a limit on how much energy a superconductor can hold before it simply doesn't accept energy any more. Now I don't know much about electricity except the basics, and my understanding of superconductors is that they are a wire that's frictionless, so that energy could go through it forever even after the powersource is gone. I also understand that they have to be kept at extremely cold temperatures(-200 C) to retain the superconductivity trait. Now my question: Is there a limit to how much energy can go into a Superconductor before it doesn't collect it any more. And if so why that happens.

Thanks in advance!

 

Unexpectedly, the largest fundamental constraint for superconducting magnetic energy storage is the same as flywheel - physical strength of a material superconductor made of or embedded in. Therefore the best examples of SMES have energy density no more then 500 KJ/kg (typically much less), the same as a carbon fiber flywheel.

https://en.wikipedia.org/wiki/Superconducting_magnetic_energy_storage

 

Read about Lorentz force. In standalone applications, however, SMES could be installed into a rocky ground to use the Earth itself as a support.

Edited April 6, 2016 by Moreno

[Enthalpy]

 

 

It's a rotational system, so the energy is 1/2 Iw², where I is the moment of inertia and w is the angular speed

Both give the same result. The angular speed version is computed from the azimutal speed.

The azimutal speed is interesting because the material's strength and density limit that one. If the diameter increases, the possible angular speed decreases but the possible azimutal linear speed remains constant. This helps figure out the limits of a flyheel.

[swansont]

Both give the same result. The angular speed version is computed from the azimutal speed.

The azimutal speed is interesting because the material's strength and density limit that one. If the diameter increases, the possible angular speed decreases but the possible azimutal linear speed remains constant. This helps figure out the limits of a flyheel.

 

 

Yes and no. If it's a solid wheel, you need to divide it into rings and find the mass and speed of each ring to use 1/2 mv^2, because they will all be different; you can do it that way but it's a lot of work.

 

If it's a ring with spokes, then using the linear equation might give a good approximation.

[John Cuthber]

Is it possible to use a superconductor without it storing energy?

[Raider5678]

Is it possible to use a superconductor without it storing energy?

I would assume so, as long as it doesn't come in contact with ANY type of electricity. Not 100% sure though.

[Enthalpy]

Is it possible to use a superconductor without it storing energy?

As soon as it conducts electricity, even so little, I'd say it stores some energy. Though, storage may not be the purpose.

 

One elegant application is to separate nitrogen from oxygen, both cold but gaseous. A porous superconducting ceramic repels the paramagnetic oxygen from its pores. Probably not a way to purify singlet oxygen as it must desexcite it.