How would a hypothetical room temperature superconductor change the world?

[AntiProtonBoy]

For pure speculative fun, let's say, a hypothetical room temperature superconductor was discovered. It has the following properties:

* Type-II superconductor.
* Very hard, somewhat brittle ceramic, like beryllium oxide.
* It has a transition temperature at 65 deg C, at which it turns into a ceramic insulator.
* Has okay thermal conductivity, but no better than copper.
* Corrosion resistant against most chemicals.
* Requires high pressure and high heat for sintering, around 1000 deg C.
* Can be made from very cheap and readily available raw elements, but purity must be good, although not as critical as Si in IC fabs.

If you could get your hands on a sample, about the size of a floor tile, what is the first thing you'd do?
Assuming you have to operate within the above constraints, how and for what application would you use this material for?
To what extent would a superconductor like this affect every day electronics and grid systems?

I'd be interest to hear from experienced engineers on this subject.

[Rerouter]

Very first thing i would do, Make a floating bed, Why? because i laugh like a maniac at the idea of falling asleep levitating above the ground.

More realistically it would be the worlds best tool holder, Note both these are based around the flux trapping effect, but what can i say this is meant to be a fun post,

[Kjelt]

To what extent would a superconductor like this affect every day electronics and grid systems? 

One tile: NOT!
Full wiring from powerplant to houses: EVERYTHING!
We could finally generate clean (DC!) power there were it has the highest efficiency because the transport losses will be zero.
So the entire Sahara will be filled with solarpanels.
All mountains with lakes will get hydropowerplants.
Other natural resources like the geisers in Iceland will be tapped to the max
And probably new clean powergenerating plants will be built in the sea where the natural movement of the warm and cold water streams can be used to generate energy.

[EEVblog]

If you could get your hands on a sample, about the size of a floor tile, what is the first thing you'd do?

Hoverboard.

[tszaboo]

A superconducting magnet, to make a  very very loud speaker which emits ultrasonic sound, which can charge a phone. And I would act like a witch in the process.
Oh wait, that is not me.
No I would make more efficient DC-DC converters to save the planet, one mW a time.

[peter.mitchell]

smaller more powerful motors, no need for all that bulky wire and magnets!

[CatalinaWOW]

You didn't mention the magnetic field saturation spec, but assuming it is comparably wonderful.

Really effective shielding (both to keep things in and to keep things out.)  Compact, cheap magnetic resonance imagers.  High speed trains.  Particle accelerators.  The list is endless.

[rob77]

superconductive "tinfoil hat" 

[CatalinaWOW]

I like the tinfoil hat.

[daqq]

To what extent would a superconductor like this affect every day electronics and grid systems?

Transportation would be the on the take very quickly - instead of expensive maglev trains imagine maglev cars and other personal transportation.

[Mechanical Menace]

To what extent would a superconductor like this affect every day electronics and grid systems?

Transportation would be the on the take very quickly - instead of expensive maglev trains imagine maglev cars and other personal transportation.

Personally I think the much less expensive maglev trains would become common place. I really can't see maglev cars been at all practical. If you can only travel on proscribed routes so exactly what's the difference between a "car" and tiny train?

[Circlotron]

Matchbox sized super duty arc welder.

[timb]

Warp engines. So we can go where no one has gone before! (Space, the final frontier.)

[T3sl4co1l]

"Room temperature superconductors" aren't as useful as they sound.

Consider this:

Why is liquid helium still so very common?

Sure, some things are just easier, like fabricating superconducting resonators out of spun niobium.  You can't work anything that's not ductile, so it's gotta be that.  Which means LHe to get it working.

But what about static magnets, for MRI, NMR, fusion experiments, and so on?  These also regularly use LHe, even though they use higher temperature superconductors.

The reason is magnetic field.

Superconduction is a surface effect.  That is: regardless of charge flow within the bulk material, only what happens at the surface matters, because magnetic fields are excluded below the surface (on the order of the London penetration depth) and therefore even DC flows under skin effect conditions!

So superconducting wires need to be extremely thin to achieve high average current density.  The films or strands need to be spaced apart as well, otherwise the local magnetic fields get too high.  You end up with Litz cable just to handle DC.

Inside a magnet, the field of course is magnified by design; but within a wire, because the current density is high and the strands are thin, you can get very intense fields just from normal current flows, as well.

So that's fine, but the kicker: critical field varies inversely with temperature, going to zero at Tc.

So a room temperature superconductor probably doesn't afford much higher current density, because it's only a small percentage below Tc.

Practical use of such a material, I think, will still require refrigeration, or will only be practical at high latitudes, during part of the year.  (Moving CERN to the Antarctic* would be interesting, but likely the logistics would well outweigh the present cost of refrigeration.)

(*But as long as we're thinking about it, yes, it would be amusing to have a relativistic proton ring circling the south pole.  It's absolutely meaningless, but kind of cute at the same time.)

Tim

[T3sl4co1l]

As for things that would be possible with such a material?

This thing. https://en.wikipedia.org/wiki/Magnetic_sail

A sufficiently large loop could thrust against Earth's magnetic field.  Which is already quite weak, so the field at the wire core needn't be terribly intense.  A sail about 80m diameter would be able to lift about 1kg, with the interesting feature that it can hover in place without any power dissipation.  It would keep itself 'inflated' as a circle (Lorentz force), but at that weight and size, it would simply blow away in the atmosphere (even with a surface-area-to-enclosed-area ratio of 1/1000, it can't be more than 20um thickness!).

It would be neat in space (you also get solar wind to deflect with such an arrangement), and you have less concern over mass (you aren't limited by hovering against a gravity well or accelerating through a viscous, turbulent atmosphere), but you need to arrange some means for shielding direct sunlight, otherwise the temperature will easily exceed limits.

Tim

[Delta]

I'd start an IGG campaign for my SuperConductoriser, which increases your superconductivity by 8x 800%.

[CatalinaWOW]

"Room temperature superconductors" aren't as useful as they sound.

Consider this:

Why is liquid helium still so very common?

Sure, some things are just easier, like fabricating superconducting resonators out of spun niobium.  You can't work anything that's not ductile, so it's gotta be that.  Which means LHe to get it working.

But what about static magnets, for MRI, NMR, fusion experiments, and so on?  These also regularly use LHe, even though they use higher temperature superconductors.

The reason is magnetic field.

Superconduction is a surface effect.  That is: regardless of charge flow within the bulk material, only what happens at the surface matters, because magnetic fields are excluded below the surface (on the order of the London penetration depth) and therefore even DC flows under skin effect conditions!

So superconducting wires need to be extremely thin to achieve high average current density.  The films or strands need to be spaced apart as well, otherwise the local magnetic fields get too high.  You end up with Litz cable just to handle DC.

Inside a magnet, the field of course is magnified by design; but within a wire, because the current density is high and the strands are thin, you can get very intense fields just from normal current flows, as well.

So that's fine, but the kicker: critical field varies inversely with temperature, going to zero at Tc.

So a room temperature superconductor probably doesn't afford much higher current density, because it's only a small percentage below Tc.

Practical use of such a material, I think, will still require refrigeration, or will only be practical at high latitudes, during part of the year.  (Moving CERN to the Antarctic* would be interesting, but likely the logistics would well outweigh the present cost of refrigeration.)

(*But as long as we're thinking about it, yes, it would be amusing to have a relativistic proton ring circling the south pole.  It's absolutely meaningless, but kind of cute at the same time.)

Tim

All true, but once you speculate one magic property, why not a couple more?  Maybe a material whose critical field is so high that it is very useable only 1% below Tc. 

[AntiProtonBoy]

superconductive "tinfoil hat" 

Now you're talking!

[T3sl4co1l]

All true, but once you speculate one magic property, why not a couple more?  Maybe a material whose critical field is so high that it is very useable only 1% below Tc.

Well if you just want to go off the slippery slope and invent Unobtanium, be my guest, but I was at least assuming the OP intended to mean, a material in line with presently known materials, but with one parameter much improved.  All the other physics would be there as normal (presumably), such as critical field.

Really, it's impossible to say if such an extrapolation is even reasonable.  We're talking a tripling of critical energy (i.e., E = k_B * T), for a coupling phenomenon whose characteristic energies are in the meV.

Speaking of meV, one might expect such superconductors to at least be "fast", i.e., with higher coupling energy comes higher frequency of the photons which disrupt it.  (Superconduction can be switched off using pulses of laser light -- in a veeery roughly analogous way as semiconduction can be "switched off" (made conductive) with a pulse of light.)  This would perhaps allow supermirrors up to far IR or thereabouts (i.e., the same wavelengths where ambient IR radiation takes place, for the same reason).  One would probably also expect, not just flux pinning as we know it, but still further nonidealities in their behavior.  (Perhaps a true zero-resistance material is not possible, but a better-than-copper resistance still is; or the current flow exhibits hysteresis and excess noise due to additional pinning and domain effects, or, who knows.)

Tim

[photon]

Quantum computer at room temperature. A shot in the arm for the PC industry.

[TimFox]

A good use would be energy storage (averaging out peak supply and load) using a very-large-area superconducting inductor.
(Don't stand on the lawn covering the buried coil while wearing a pacemaker, however.)

[StuUK]

Well if you just want to go off the slippery slope and invent Unobtanium, be my guest,

WHAT! Its not real 

[Circlotron]

A good use would be energy storage (averaging out peak supply and load) using a very-large-area superconducting inductor.
(Don't stand on the lawn covering the buried coil while wearing a pacemaker, however.)

I wonder if there is an upper limit to the amount of energy you could store in a superconducting air cored inductor? With a moving magnetic field you have a corresponding electric field; not sure about a magnetic field with changing intensity. This electric field may present flashover problems if taken far enough, but with a static magnetic field is there actually an upper limit to energy storage?

[TimFox]

Both a moving magnetic field and a time-varying magnetic field will induce an electric field (see Maxwell's equations).
I knew a researcher back in the 1970s working on a practical device (using conventional superconductors) who pointed out that the strength-of-materials questions (how to keep the thing from flying apart) favored a coil over a flywheel for energy storage.

[T3sl4co1l]

A good use would be energy storage (averaging out peak supply and load) using a very-large-area superconducting inductor.
(Don't stand on the lawn covering the buried coil while wearing a pacemaker, however.)

I wonder if there is an upper limit to the amount of energy you could store in a superconducting air cored inductor? With a moving magnetic field you have a corresponding electric field; not sure about a magnetic field with changing intensity. This electric field may present flashover problems if taken far enough, but with a static magnetic field is there actually an upper limit to energy storage?

Yes. Critical field (maybe 1-2T for our hypothetical material, 15-20T for most real ones at practical, usually LHe temperatures) must be higher than field at the center.  Mechanical strength also matters, because pressure goes as B^2/mu.  (Pressure == energy density, so you get that at the same time, too.)  Whichever fails first -- critical field or mechanical strength -- determines maximum energy density.

Most superconducting wire is made embedded in copper, so the allowable EMF while maintaining good efficiency (say, without boiling off your cryostat and quenching the whole thing at once) will not be too much.  This limits power density.

Tim