Innovative superconductor fibers carry 40 times more electricity

Sep 07, 2011
This is a demonstration of "quantum trapping" in Dr. Almog's laboratory. Credit: AFTAU

Wiring systems powered by highly-efficient superconductors have long been a dream of science, but researchers have faced such practical challenges such as finding pliable and cost-effective materials. Now researchers at Tel Aviv University have found a way to make an old idea new with the next generation of superconductors.

Dr. Boaz Almog and Mishael Azoulay working in the group of Prof. Guy Deutscher at TAU's Raymond and Beverly Sackler School of Physics and Astronomy have developed superconducting wires using fibers made of single crystals of sapphire to be used in high powered cables. Factoring in temperature requirements, each tiny wire can carry approximately 40 times more electricity than a copper wire of the same size. They have the potential to revolutionize , says Dr. Almog.

High power superconductor cables take up much less space and conduct energy more efficiently, making them ideal for deployment across grids of electricity throughout a city. They will also offer a more effective method for collecting energy from , such as solar and wind energy. Superconducting wires can also be used for and enable devices which enhance grid stability.

The new were first presented at the Israel Vacuum Society Conference in June 2011, and will be shown at both the European Conference on Applied Superconductivity and the Association of Science Technology Centers Conference this fall.

Beating the heat

One of the things that make our inefficient is overheating, Dr. Almog explains. Due to found in the metal, some of the energy that flows through the cables is cast off and wasted, causing the wires to heat up. But with superconductors, there is no resistance. A self-contained cooling system, which requires a constant flow of , keeps the wire in its . Readily available, non-toxic, and inexpensive — a gallon of the substance costs less than a gallon of milk — liquid nitrogen provides the perfect coolant.

Even with the benefit of liquid nitrogen, researchers were still hard pressed to find a material that would make the ideal superconductor. Superconductors coated on crystal wafers are effective but too brittle, says Dr. Almog, and although superconductors on metallic tapes had some success, the product is too expensive to manufacture in mass quantities.

To create their superconductors, the researchers turned to sapphire fibers, developed by Dr. Amit Goyal at the Oakridge National Lab in Tennessee and lent to the TAU team. Coated with a ceramic mixture using a special technique, these single-crystal fibers, slightly thicker than a human hair, have made innovative superconductors.

Going macro

Dr. Almog is currently working to produce better superconductors that could transport even larger amounts of electric current.

One area where such superconductors could lend a hand is in collecting renewable energy sources. "Sources such as wind turbines or solar panels are usually located in remote places such as deserts or offshore lines, and you need an efficient way to deliver the current," explains Dr. Almog. These superconductors can traverse the long distances without losing any of the energy to heat due to electrical resistance.

Superconducting cables could also be an efficient way to bring large amounts of power to big cities "If you want to supply current for a section of a city like New York, you will need electric cables with a total cross-section of more than one meter by one meter. Superconductors have larger current capacities using a fraction of the space," says Dr. Almog. Different parts of a city could be cross-wired, he adds, so that in the event of a blackout, power can be easily rerouted.

Inspiring young scientists

Developing a superior superconductor is only part of TAU's mission. Dr. Almog is also dedicated to making this technology accessible and exciting as a way to capture the imagination of aspiring scientists. TAU has manufactured superconductor wafers which, filled with liquid nitrogen like their cable cousins, can be locked in place by strong magnets and levitate. Placed on a magnetic track, the wafer zooms through the air like George Jetson's space-age car. It might look like magic, but it's actually a phenomenon called "quantum trapping." Kits that demonstrate this "magnetic levitation" have been distributed in science museums throughout Israel, and Dr. Almog hopes to expand their distribution internationally.

And when the day's work is done? "We also make ice cream with the liquid nitrogen," Dr. Almog grins.

Explore further: Electron spin could be the key to high-temperature superconductivity

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Eikka
4.4 / 5 (8) Sep 07, 2011
Readily available, non-toxic, and inexpensive a gallon of the substance costs less than a gallon of milk liquid nitrogen provides the perfect coolant.


Unless you need a gallon per day for every mile of cable. It's mighty hard to insulate a long wire so well that there's no venting.

The embodied energy to make a kilogram of liquid nitrogen is about 0.2 kWh as far as I can figure it out, or somewhere around ½ kWh from the average primary energy sources.

A ballpark figure of 0.81 kg/L gives us the embodied energy of a gallon of liquid nitrogen at 1.5 kWh/gal, so if you need a gallon per day to counteract venting, you would be wasting 65 Watts all the time.

It does work out to be sensible at powers of over about 1-2 kW transferred, if we contrast it to a 5% loss in copper. The difficulty is that the power loss scales with power and lenght with copper, but only with lenght using superconductors, so longer lenghts of superconducting wire may need higher power to be economical
SiBorg
4.5 / 5 (4) Sep 07, 2011
Lots of exciting applications and whatnot, no one doubts the potential for superconducting cables. The truly interesting thing this article seems to miss is whether sapphire fibres are any easier to manufacture than the (presumably) cuprate tapes mentioned at the start of the article.
Eikka
3.2 / 5 (5) Sep 07, 2011
After all, when you disconnect a load from a copper wire, the losses are reduced to capacitive AC leakage which is completely neglible over short to medium distances. If you disconnect a load from a superconducting cable, it's still using liquid nitrogen.

Plus, there's some power involved in pumping the LN2 over miles and miles of cable at a certain rate to stop it from developing insulating bubbles that would kill the superconductivity.

It has a certain idling power requirement, which necessitates a certain minimum power draw to save any energy over traditional copper and aluminium wires.

kevinrtrs
1.1 / 5 (8) Sep 07, 2011
Just how expensive will the sapphire wires be? No wonder more work is required - thieves would be very glad to steal these cables instead of the copper.
rawa1
1.1 / 5 (7) Sep 07, 2011
We shouldn't forget, before ten years J.F.Prins revealed superconductivity above diamond at 300 K. This finding has been ignored with community of physicists and never attempted to replicate in the same way, like the cold fusing of hydrogen at nickel, revealed with Piantelli & Foccardi

http://www.iop.or...8/3/319/
Jeddy_Mctedder
3.3 / 5 (7) Sep 07, 2011
this will be a revolution, but it will never power 'cities' where real world concerns about cooling will drive up the system price. that will only happen when there are room temperature superconductors, and those probably won't happen for 100 years.

this WILL work for specialized applications of ALL SORTS. already superconducting systems are being used to scale down massive naval ship motors, they are used for powering mag-lev demonstration trains which one day will replace convetional airports as they can accelerate trains to multi-mach speeds within vaccum tunnels at under 10% of the energy requirements of moving a plane at 600 miles an hour.

the navy's magnetic rail and coil guns already need cooling. a future hand held coil gun will eventually replace silenced weapons for covert operations since there is NO explosion of any kind to make noise and no explosive residue left behind for detection.

superconducting and magnetism are the future. and the future is already here a bit.
Moebius
3.2 / 5 (5) Sep 07, 2011
Just how expensive will the sapphire wires be? No wonder more work is required - thieves would be very glad to steal these cables instead of the copper.


Very doubtful. They don't have any intrinsic value because they are Sapphire (unless you know of a microscopic civilization that wants to cut microscopic gems). Their value is strictly as a superconductor. Not much of a black market for superconducting wire.
Scottingham
3 / 5 (2) Sep 07, 2011
Eikka, I share your concern about the maintenance of the liquid nitrogen.

I was thinking though that a suitably long superconducting cable would have liquid nitrogen generators (air is full of the stuff!) along the cable itself (possibly along power lines where transformers currently are) just drawing current off as it needs it.
lengould100
4 / 5 (5) Sep 07, 2011
Well, sapphire itself is simply crystalized aluminum oxide (corundum), one of the cheapest and most abundant raw materials on earth. If a means can be found to produce the sapphire strands directly from a furnace rather than having to machine them from larger boules of artificial sapphire now used industrially, this system could have legs. A braided conductor of strands offers good passage for the coolant, too.
Eikka
not rated yet Sep 07, 2011
I was thinking though that a suitably long superconducting cable would have liquid nitrogen generators (air is full of the stuff!) along the cable itself (possibly along power lines where transformers currently are) just drawing current off as it needs it.


Well, that would be mandatory, since nobody's going to go around delivering liquid hydrogen on a truck. That would take even more energy.

You need to section the powerline, and install coolers to keep the liquid nitrogen as a liquid, and pumps to circulate it within the sections so there's no nitrogen bubbles that could let the cable heat up locally.

A section that is too long risks having the nitrogen return back the other way as gas, because it gains too much heat along the way and boils. Pumping it around faster involves friction, which heats the liquid faster, so there's probably a maximum lenght of wire that can be effectively cooled.
Parsec
not rated yet Sep 07, 2011
Just how expensive will the sapphire wires be? No wonder more work is required - thieves would be very glad to steal these cables instead of the copper.

I have pretty high confidence that sapphire in wires thinner than a human hair wouldn't have excessive value on the street for jewelry. And that's assuming you could get the ceramic off without turning it into duct, and also assuming that you can deal with the liquid N2 you would have to get through.
Skultch
not rated yet Sep 07, 2011
It has a certain idling power requirement, which necessitates a certain minimum power draw to save any energy over traditional copper and aluminium wires.


Just wanted to highlight the last part of this, since so many are concerned about thieves: IIRC, the overwhelming majority of long distance power lines are made of aluminum, not copper. 1/4 the price per pound. Also, IIRC, the vast majority of scrap metal theft is from construction sites, not high voltage power lines in use. haha There are softer targets.
Nik_2213
5 / 5 (2) Sep 07, 2011
The superconducting material is coated onto the sapphire fibres as support ? Sounds like fun...
FWIW, our lab's liquid chromatography pumps had sapphire pistons, which were as colourless as good glass, so utterly un-gem like...
Uh, in UK, a major target for copper theft is railway signal cabling. However, several posthumous 'Darwin Awards' have been earned by thieves who've targeted grid sub-stations-- While they were 'live' !!
that_guy
5 / 5 (1) Sep 07, 2011
We shouldn't forget, before ten years J.F.Prins revealed superconductivity above diamond at 300 K. This finding has been ignored with community of physicists and never attempted to replicate in the same way, like the cold fusing of hydrogen at nickel, revealed with Piantelli & Foccardi

http://www.iop.or...8/3/319/

I don't believe that sapphire is ideal, but it can be seeded like you would make a sugar crystal, at room temperature and pressure. Diamond cannot.

We are talking about several orders of magnitude of price difference.

http://en.wikiped...Sapphire

Please read the part about synthetic sapphire. This applies to like 6 of you commenters. They make it just like they make the silicon crystals for computer chips. high end watches have sapphire windows, Etc, etc. I didn't know that this would be so unknown amongst a bunch of nerds like us!!
Callippo
1 / 5 (2) Sep 07, 2011
I don't believe that sapphire is ideal, but it can be seeded like you would make a sugar crystal, at room temperature and pressure. Diamond cannot.
The sapphire fiber is serving as a passive support for another superconductive layer. Whereas at the case of diamond the electrons are attracted to the oxygen holes beneath the diamond surface and they're forming a conductive surface layer above it at vacuum. It's completely different approach to superconductivity.
Burnerjack
2 / 5 (4) Sep 07, 2011
Can't wait to see somebody complain "They're contamitating the air with nitrogen.
Urgelt
5 / 5 (2) Sep 07, 2011
As always with superconductivity, scaling up economically is the problem. It doesn't sound like they've solved that problem.
ED__269_
5 / 5 (1) Sep 08, 2011
J.F. Pinns document doesn't seem believable, thats probably why it was forgotten about over 10 yrs ago. IOP suddenly lost standing in my eyes.

As soon as I read his assumption of a seemingly electron cloud increasing in density, that by virtue of space availability suddenly become bosons forming Cooperpairs? I suddenly got the desire to throw the pdf away.

better keep it though, since I'm in the process of learning superconduction... even seemingly bad ideas raise good question and have novel ideas.
adamindc
5 / 5 (1) Sep 08, 2011
But how much electricity can God carry? (kidding)
rawa1
1 / 5 (3) Sep 08, 2011
J.F. Prins document doesn't seem believable, thats probably why it was forgotten about over 10 yrs ago.
His experiment just demonstrated the whole fundamental principle of high-temperature superconductivity. If electrons are getting squished enough, their repulsive forces compensate mutually from many directions and the electrons will move freely. This experiment demonstrated, how to create superconductive phase of electrons artificially - simply with compression of electrons into small volume. IMO this experiment belong together with cold fusion at nickel and Podkletnov's antigravity beams into three main findings of the physics of the 90's of the last century. They're all ignored with physicists, who are seeking for supersymmetry, Higgs boson and gravitational waves - i.e. the things, which I personally consider unbelievable. What worse, these things have no practical applications with compare to the above findings.
yoatmon
5 / 5 (1) Sep 08, 2011
Why all this poppycock? Just use graphene at normal room temperature where its conductivity is some 100 times better than copper.
ED__269_
5 / 5 (1) Sep 08, 2011
@ Rawa1
I knew what Prinns was getting at. the "?" was about "did he just say that in a science publication?"

let me ask you these two questions; It is known that resistance remains proportional to temperature except @ critical temp for superconductors where it goes to zero.

therefore

WHAT IS RESISTANCE in terms of the electron-electron interaction?

Can you answer that and still believe Prinns?

@ yoatmon.
yes, why not?
Bogey
not rated yet Sep 11, 2011
Im thinking perhapse these cables could be used in a hi end HiFi set up. Should be a lot cheaper than some of the exotics you see. Any techy thaughts.

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