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Superconducting Cables To Carry Power In Detroit

timothy posted more than 13 years ago | from the but-what-kernel-do-they-run? dept.

Technology 161

bewert writes: "Check out [this Knight-Ridder wire story.] This could change electricity distribution economics as we know it. A project is under way to replace 9 major copper power distribution cables with 3 smaller ones made from a high-temperature superconducting material called BSCCO (pronounced bisco). Pretty interesting technology, and one that could have huge implications for reduction of transmission power losses and the need for more generation." Not to mention that it means a 25-fold reduction in the weight of the cables used to carry electricity for a large chunk of Detroit.

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Cable is light... (1)

Anonymous Coward | more than 13 years ago | (#435818)

Cable is light... But liquid nitrogen cooled? How would that react under (summer heat, nuclear war, y2k, world war 3)

Re:Cable is light... (1)

Anonymous Coward | more than 13 years ago | (#435819)

What you talking about foo?
y2k=year 2048..
Every self-respecting dork should know that...

Re:Supercoductors won't help that much with AC (1)

Anonymous Coward | more than 13 years ago | (#435820)

The line losses are mostly from resistance. Power disapated is equal to I*I*R. In fact, line losses are commonly called "i-squared r" losses. That's why we use high voltage lines for long distance transmission- higher voltage means the current required for the same power is less. Power = V*I, so raising voltage means less current. Less current means less resitive losses. Net-net, less resistance is a good thing.

Part of the reason we use AC is that it's easy to change it's voltage, which comes in handy when you step it up at the generator to put on the grid, and step it down several times before it's actually used. Another reason though is it's *much* easier to generate. DC generation requires commutators & brushes, which have to be replaced, etc. Also, most household electric loads do fine with AC. Lights, anything with a motor or a resitive heater (>90% of household loads) do just as well if not better with AC.

corrections to the engineering of power cables (5)

Anonymous Coward | more than 13 years ago | (#435821)

Yikes, let's clean this engineering up.

1. One of the main reasons for using the HTS cables is space. Detroit Edison needs to increase the current carrying capability at the station, and using the HTS means they get more capacity with the same underground conduit, so they don't have to excavate to improve the circuit. big savings. Plus, the smaller diameter and weight make it easier to pull the cable through the conduit, and eliminates the need for splices in the cable due to maximum pull weights. Bad splices are a common cause of failure in underground cables. Of course, if you are ComEd in Chicago, you just ignore that until the city goes dark...

2. Cables have higher capacitance than overhead transmission lines, because the conductor is closer to the ground potential. It also has lower inductance for the same reason. There is no external electric field. The sheath is at ground potential, so the field is between the conductor and the sheath.

3. Long distance cables are typically DC because in high voltage AC cables the voltage increases at the sending end due to the high capacitance of the line. That's why underground AC networks have shunt reactors, to keep the voltage down.
Although inductance does reduce the maximum power transfer in a circuit, it's due to its affect on voltage.

4. Although the lossless characteristics of HTS are important, that doesn't by itself make the economics attractive. Avoiding construction costs and pushing more power through the same rights of way due to higher current density is the niche that HTS is currently filling.

Elvis, the power engineer-nerd.

Frozen birds and burning cables? (2)

jbuhler (489) | more than 13 years ago | (#435823)

The first bird that perches on these power lines and puts a talon through the insulation is going to get a nasty surprise.

I wonder what the cooling system looks like for these new lines? It seems quite challenging to cool all that cable and prevent any LN2 leakage. More importantly, if a leak happens, and the cable rises above its transition temperature while carrying a large current, there must be some kind of backup system to shunt off the current and prevent the heat generated by the sudden resistance from damaging the cable. Perhaps that's why the ceramic ribbon is wrapped in silver.

I don't do hardware -- would some actual power engineers care to comment on the cable design?

Finally! (1)

dfetter (2035) | more than 13 years ago | (#435827)

A cool use for high-Tc superconductors :)

Re:Superconducting storage loop (2)

stripes (3681) | more than 13 years ago | (#435829)

No offense, but unless I missed an important lecture in thermodynamics, how can they hope to make money from this? It takes more power (which equals money in the eyes of the power companies) to pump water uphill then they can get from it going downhill...

You didn't miss a thermo lecture, just a economics one. A given commody market value can vary over time. Storing it and paying rent on the storage and selling it later can be quite profitable. It can also lead to quite a loss if the price never goes up enough (or you can't wait that long).

That's what makes the stock market work. And the power market. And the futures market. And...

Re:This doesn't sound all that useful (3)

stripes (3681) | more than 13 years ago | (#435830)

Trading a thick heavy but otherwise low-maintenance copper cable for a thin light but very high-maintenance superconducting one?

According to the article the existing copper cables are cooled with oil. I expect that means they are only replacing existing high mantinance (high capicity?) cables with these things.

I don't know enough about power distribution systems to know where these cables live, but I'm betting they are not the overhead phone pole kind. Maybe they are only found much closer to the genneration systems.

Re:This will make power loss in space less. (1)

amorsen (7485) | more than 13 years ago | (#435833)

Space may be cold but it is a wonderful insulator. The only way to lose heat in space is to radiate it off. Keeping a superconductor cold enough would be a challenge.

Re:Frozen birds and burning cables? (1)

amorsen (7485) | more than 13 years ago | (#435834)

Liquid nitrogen is a lot of fun. You can stick your finger into it without being harmed. You only get hurt by it if you drink it or if you touch water that has been in contact with it. (Water ice cooled by liquid nitrogen is fairly nasty. It sticks.)

Re:Supercoductors won't help that much with AC (1)

amorsen (7485) | more than 13 years ago | (#435835)

Going AC->DC->AC is getting fairly cheap these days with power electronics. Of course it would be much nicer if we just got rid of AC.

Hmmm... Better check the near space... (2)

Pig Hogger (10379) | more than 13 years ago | (#435836)

Better check nearby space for Kemplerer Rosettes, so we can be sure we won't get mysterious bouts of superconductor plagues...


Re:Supercoductors won't help that much with AC (1)

Omnifarious (11933) | more than 13 years ago | (#435838)

If I'm not mistaken, the phase shift that inductance causes can be a big source of loss too. If your voltage and amperage waves are completely out of phase with eachother, you lose most of your power. So, I suspect in that way you can use capacitors to keep that from happening.

Bisco (1)

Space (13455) | more than 13 years ago | (#435840)

Would you call any computations concerning Bisco, Bisco-Math? IIRC, wasn't Bisco-Math the primary means of computation in one of Douglas Adams' ships in the Hitchhikers Guide Trilogy?

Re:Bisco (1)

Space (13455) | more than 13 years ago | (#435841)

Found a link [] to the bistromathematic drive

A little more on HTSC and BSCCO/Ag Tape (4)

doom (14564) | more than 13 years ago | (#435842)

As usual, newspaper technical articles are pretty sketchy on the interesting bits.

For instance, temperature is just one parameter to look at when you're looking at superconducting cables. Increasing the current density and/or the magnetic field will also tend push you out of the superconducting state. Tc is the temperature when current and field is zero, and the trouble with the high Tc superconductors is that you don't have a lot of clearence between the temperature of liquid N2 (77K) and Tc. When you try and load the cable with current, what you might call the "effective" critical temperature is going to be lower. The easy form of BSSCO is only something like 90K -- can't believe I don't remember more precisely than that, I used to work on this stuff -- anyway, I refuse to believe that they've managed to reliably come up with the 125K form of BSSCO, that's one holy grail that was looking pretty elusive, at least as of ten years ago.

A minute with google turns up what looks like a pretty good technical article about the processing of BSCCO/Ag tape: Is Low Cost BSCCO Tape Just Around the Corner? [] . (ObGripe: sure would be nice if the slashdot crew would do a teeny bit of background research on these stories, instead of just pointing us at junk news sources). Looks like I might be wrong about the 125K form of the stuff: they talk about working with both the 2223 and 2212 compositions (the numbers there are the main stoichiometries of the compound, e.g. Bi2 Ba2 Ca2 Cu3 Ox... as I remember it they don't usually specify the amount of Oxygen in the mix, because it's a bitch to measure it, and it tends to vary anyway). But then, they wouldn't be talking about both forms if they had the 125K form working really well.

Looks like they've got some decent numbers from direct measurements of current/area, which makes sense, or they wouldn't be announcing projects like this.

(By the way: one of the cool things about BSCCO -- I wonder when they made up this "Bisco" business, that's a new one on me -- but all the components are relatively non-toxic. At least they're not using something really evil like Thallium.)

Re:This doesn't sound all that useful (1)

Eivind (15695) | more than 13 years ago | (#435846)

The article states that the old copper-cables where cooled by oil. Thus the argument that you're using energy to circulate the nitrogen is likely irrelevant, since circulating oil takes a lot *more* energy, especially since the old copper cables produce heat.

Underground cables typically need to be cooled in some fashion if they're high-capacity, otherwise the heat would keep building up and cause damage at some point. (not to mention that resistance increases with temperature in copper, so you want them cold for reducing transmission-loss.)

speaker wire! (2)

Dr. Tom (23206) | more than 13 years ago | (#435849)

Excellent! Now I can finally replace my gold metal speaker wires with liquid nitrogen cooled, silver encased, bisco ribbon cables! Then I'll finally be able to sleep at night. Well, as long as I have the cryo, can I replace my tubes with Josephson junction? Thermal noise begone!

Re:Huh? (1)

SEWilco (27983) | more than 13 years ago | (#435854)

"High temperatures", like 22 degrees C? I don't think so. Not that high yet.

Not for California (1)

Grimwiz (28623) | more than 13 years ago | (#435855)

This system has a much higher energy density than copper cables. If something happens to a copper cable you get an arc which may cause a fire but hopefully the cutoff will stop the current before that happens.

If you're carrying more electricity, then the cutoff has to be higher, and if you take the explosive effect of converting liquid nitrogen back to a gas by applying heat which in itself will cause the superconductor to stop superconducting I believe you'd get quite a big bang.

I've seen the effect of too high a safety cutoff, in a (experimental) home storage heater that was designed to be high-ampage but it had a break in its insulation and leaked 5000watts straight back to earth. It melted the bricks round the cable but still didn't trip the fuse.

So to summarise, don't put the wires anywhere where the cooling can be lost, such as in earthquake zones. That'll have to wait for room temperature superconductors.

disruptive magnetic fields (1)

Arlet (29997) | more than 13 years ago | (#435856)

I've always understood that this type of higher temperature superconductivity breaks down in the presence of strong magnetic fields, such as produced by strong currents in the material itself.

Any ideas how this has been solved ?

Re:Savings is in power loss (2)

tbo (35008) | more than 13 years ago | (#435858)

Oops, that's Y Ba_2 Cu_3 O_6 superconductors, and I may also get to play with NbSe_2 superconductors, too. The cyclotron is pretty cool, too.

Savings is in power loss (3)

tbo (35008) | more than 13 years ago | (#435860)

The energy savings is in power loss. I suspect space/weight savings are secondary. Superconductivity means no resistive power loss, whereas normal transmission means usually lose you 10% or so.

As for the cost of cooling the nitrogen, that's trivial. LN2 is as cheap as soda pop.

This summer, I'll be working at the local particle accelerator doing beta-NMR and muon spin rotation experiments on high-temperature superconductors... Should be lots of fun! We aren't studying that particular kind, though (I think just the Yt-Ba-CuO ones).

Re:Savings is in power loss (1)

oolon (43347) | more than 13 years ago | (#435863)

But the looks of it the system is an experiment, everyone has mentioned problems, like super conductivity break down, cooling problems and the like. I feel, they are building it to find out how to solve these problems, as its built it might as well work for a living, but that is not WHY it was built.


Loss through inductance (1)

Hank the Lion (47086) | more than 13 years ago | (#435864)

> The majority of the loss is due to inductance

Although inductance is an impedance, i.e. it will limit the current that is transmitted at a specific voltage, it does so without loss.
The only loss through inductance is indirect. Power delivered is V*I*cos(phi), and thus diminishes when voltage and current are out of phase. Power lost is I*I*R, and thus independent of cos(phi). For the same power delivered, lowering cos(phi) will diminish efficiency, _as_long_as_there_is_R_! Without resistance, the cos(phi) will not matter!

Re:not getting this... (1)

BlaisePascal (50039) | more than 13 years ago | (#435865)

Besides, "High Temperature" for a superconductor means "above 79 Kelvins". Considering that the Holy Grail of superconductor research is "room temperature", meaning "above 280 Kelvins", the high temperature stuff isn't that hot.

Re:Superconducting storage loop (1)

Rocky (56404) | more than 13 years ago | (#435868)

No, no, no!

1) You can't win.

2) You can only break even on a cold day.

3) It never gets that cold.

tapping the powerlines for cooling (1)

radja (58949) | more than 13 years ago | (#435869)

wow.. maybe I should move to the US, where you can't only run your computer on illegally tapped power, but also tap the liquid N2 for that perfect overclocking cooling system!


Re:Superconducting storage loop (1)

abartlet (64597) | more than 13 years ago | (#435870)

And when you run on a spot market, power on 30 seconds notice can be sold for quite a tidy profit. (Even power on 10 minutes notice, the way these plants normaly work, can be sold for quite a tidy profit).

These plants make their money becouse off-peak power is cheap but on-peak power can be very expencive.

Re:This doesn't sound all that useful (1)

grayghost (65596) | more than 13 years ago | (#435871)

The cables they are replacing are already oil cooled so there is not a great increase in maintenance.
They are replacing 9 wires with 3. I am guessing these are parallel lines running underground. The 3 will take up much less room, which is a big deal. In central cities power lines are run through underground conduits/pipes. These conduits are very crowded due increasing power requirements in central cities. Replacing copper lines with superconducting lines allows the power companies to meet rising power requirements without tearing up the streets to lay new conduits.

Re:Savings is in power loss (1)

tacpprm (67226) | more than 13 years ago | (#435872)

Of course we have to remember that refrigerating nitrogen takes a fair bit of energy.

It will be interesting to see how much they have to spend on cooling & maintaining the cladding on the cables.

A loss of cooling would be interesting as well - the transition from superconductor to insulator as these materials warm up is quite abrupt.

I don't think that a section of power grid would have a high enough energy density to cause much damage if it lost superconductivity (unlike some magnets & storage rings), but you might get a bit of boiling nitrogen coming out of the ground.

Oh, that's just GREAT... (3)

iceT (68610) | more than 13 years ago | (#435874) replace 9 major copper power distribution cables with 3 smaller ones...

So, we'll only need to have 3 cables break before Detroit will lose power...

There's something to be said for redundancy and multiple paths...

Fuck moderation, I have to answer to this! (1)

haggar (72771) | more than 13 years ago | (#435875)

Sorry, but who said microporcessors have to be made out of smi-conductors? Thet's NOT the only technology that allows the creation of logical circuits. There is an ATM switch, for example, made by Hitachi, that uses superconducting circuitry. [] The superconducting devices I know of, use the Josephson junction to operate as logical gates. Derivatives are Single Flux Quantum Logic and Quantum Magneto Flux Logic. And Josephson junctions are not new technology, actually. We studied them in Uni 7 years ago, from a book that was already 4 years old.

I am sure this only shows what is the difference between a self-proclaimed geek mentality, and a scientist: a true scientist is open-minded, while the others can't see over their nose. That's why most of ./ readers will claim Linux to be superior to anything, even if they don't know about the laternatives. Same thing here: there is a whole world of different solid-state technologies that are not based on silicon, you just have to open your mind to, arrgh, sciences like phisics and chemistry.

Superconducting CAT5? (1)

NOC_Monkey (73018) | more than 13 years ago | (#435877)

Hmm... Imagine the possibilities of a superconducting network cable. Loop-length restrictions could become a thing of the past, repeaters would be almost totally unnecessary, and the geek factor is nearly off the scale. Grated, this would only work for systems using copper wiring (though a fiber that was truly 100% transparent would also be nifty).

Good, Detroit power SUCKS. (1)

JBMcB (73720) | more than 13 years ago | (#435878)

I didn't glean from the article if Detroit Edison is sponsoring the technology, Detroit Public Lighting, or Detroit Edison, the two major players. I assume it's Detroit Edison, as DPL usually operates with a deficit. This would be a boon for the stability of the grid, as the Detroit Public Lighting grid has had repeated, major problems in the last few years, mainly with their central distribution lines which feed the smaller lines running out to communities and schools. I hope the city of Detroit gets the hint and starts dissolving the antique public service.

Re:Supercoductors won't help that much with AC (1)

papa248 (85646) | more than 13 years ago | (#435880)

At 500kV, you have an incredible amount of loss! Assuming a relatively low resistance, say only an ohm, you're losing thousands of watts of power to heat over a lenghthy run. (P=V^2/R) As far as inductance and capicitance goes, this doesn't effect the overall power, ie, it is not parasitic. They change the phase of the current waveform, which IS a problem still, because the line load needs to match the waveform to get the maximum power transfer and the smallest reflection coefficient.

Re:You don't lose 10% (2)

papa248 (85646) | more than 13 years ago | (#435881)

Even with only 100A of current, there still is a huge amount of loss in the line. I very recently graduated with my EE in power systems as well. A tour of Detroit Edison not long ago confirmed this.

Re:This doesn't sound all that useful (1)

Alpha State (89105) | more than 13 years ago | (#435883)

I suspect it is also justified as a test case. These cable could be much more useful for long distance, large-scale power transfers. For example, in Calif. at the moment, they are going to have to import power from other states, but this is wasteful because of the transmission distance.

Things will be easier if we don't have to produce power close to where it is consumed. This isn't just a case of moving pollution to someone else's back yard - the "power loss" due to having to transport fuel counts for a lot too.

I know here in Australia they have at least 2 long distance DC links due to the lower losses. Superconductiong cables would be wothwhile in this case due to huge power savings. As for maintenance, the main problem with ordinary cables is overheating when they are heavily loaded, the problems of SC cable will be totally different, and I think it's a bit premature to speculate on them. Obviously the SC cable will cost more in general but we're talking about a lot of power savings (and with the price increasing).

Finger stirring (1)

chainsaw1 (89967) | more than 13 years ago | (#435884)

It will only work for as long as the heat/energy contained in your finger is high enough to maintain boiling the liquid before it begins to cover your finger. After that point, your finger will quickly become like the raquet balls, pens, and other items that get shattered for demonstrations.

Your finger has an advantage in that hot blood gets circulated to it, so it generally can boil the N2(liq) for longer than similar sized inanimate objects.

This doesn't sound all that useful (2)

JoeShmoe (90109) | more than 13 years ago | (#435885)

Trading a thick heavy but otherwise low-maintenance copper cable for a thin light but very high-maintenance superconducting one?

I'm trying to picture this setup in my mind. As best I can figure, there is an underground conduit that has a single cable running through it, that they then pump full of liquid nitrogen.

They say it can carry electricity with virtually no resistance, but consider the electricity to cycle the liquid nitrogen and cool it down when it evaporates?

Since it's all underground, I don't see the space saving aspects of reducing nine wires to three.

Can anyone explain the key advantage to this new system? Is copper becoming that scarce/rare that they can't just throw down three more copper cables to increase capacity?

- JoeShmoe

Re:Superconducting storage loop (2)

steveha (103154) | more than 13 years ago | (#435891)

I don't think such a system is practical yet.

The most practical energy storage system in use right now is pumped storage hydroelectric.

This is used with a hydroelectric generator plant. When demand is low, it will use excess power to pump water uphill into a reservoir; then, during peak demand times, it uses water from the reservoir to generate electricity. Here's a link [] to one in Oklahoma.


Re:This doesn't sound all that useful (4)

steveha (103154) | more than 13 years ago | (#435892)

Can anyone explain the key advantage to this new system?

I really want to read more details about this. But I'm pretty sure that the key advantage is the lack of resistance.

Superconducting wires don't just have less resistance to current flow, they have no resistance at all. A superconducting cable will not have any losses due to resistance. (This means that when you run current through the superconducting cable, the cable won't heat up, so the cable won't be boiling off your liquid nitrogen.) I guess the reduced losses make up for the power needed to keep the cables as cool as liquid nitrogen.

My main worry is whether depending on liquid nitrogen for cooling will make this system more prone to failure. I'm sure they are not replacing all the copper, at least right away!

They wouldn't take risks with this if they were just breaking even. I'm sure that the new cables can carry more electricity than the ones they replace, not just the same amount; and the reduced losses might mean the same power plants can provide more useable power than previously.


Good to See Progress, but still Potential Issues (2)

JeffRC (103922) | more than 13 years ago | (#435893)

I doubt there is any substantial weight savings in the superconducting cabling system. While the superconductor is substantially lighter than the copper, the cooling jacket (we're probably talking a vacuum insulated LN2 jacket) is probably quite heavy.

There are also some technology/safety issues related to the operation of superconductors. A superconducting line carrying a large amount of current can do some pretty catastrophic things if the temperature rises above the critical superconducting temperature. The transition from no resistance to substantive resistance can turn the wire into a nice big heater element inside an LN2 cooled system. Explosive vaporization of the superconducting element has happened in laboratories before. The other problem to be alert for is critical current. Superconductors are only superconducting up to a critical current level. Attempts to pump more than the critical current through the wire will result in it transitioning from superconducting to normal conductivity with the same results as above.

I'm sure the engineers who have designed the system have taken this into account. But the deployment of a crygogenically cooled power distribution system is far from a trivial exercise.

BTW, I've been told that power distribution systems consume almost half of the power generated just in getting the power from the plant to our homes/offices. Also while the superconducting lines can save a lot of energy, it takes a lot of energy to make LN2.

Re:Cable is light... (1)

Cheshire Cat (105171) | more than 13 years ago | (#435894)

Cable is light... But liquid nitrogen cooled? How would that react under (summer heat, nuclear war, y2k, world war 3)

Oh jesus....I'm sure it would be fine in the summer heat. If there was a nuclear war, getting power to detroit probably doesn't rank really high on priorities. No one'll need lights since they'll glow anyways! :)

And dude, Y2K ended last year.

Never mind (2)

oojah (113006) | more than 13 years ago | (#435896)

Having read a good few responses to this article, I have come to the conclusion that I often do when reading slashdot.

A little ignorance goes a long way.

Come on people, don't post just for the sake of it.


Re:You don't lose 10% (2)

williamwallace14 (125386) | more than 13 years ago | (#435899)

Looking though some EE books I have, the actual power loww of a 10km wire (1/4 inch diamete) is going to be around 4.7% or so. This is actually using methods in Physics more than in circuit analysis, but should still work.

Also, the frequency is a major contributing factor in such line, being the higher the frequency (8khz as compared to 4khz) you get from around 500 watts power loss to 2000 watts depending how much your line amperage is (RMS).

Lastly, though inductors can cause more power loss than the line resistance themselves, you have a assume you have a high variance of power output from a power station. The less the variance, the less that has to do with induction. But, in the cases of power spikes and such, I think I'd take power loss over my house being pumped with 500 amps (when ~200 is what's running my computers, TVs, toasters, etc).


Energy economy of cooling (1)

bmasel (129946) | more than 13 years ago | (#435900)

They say it can carry electricity with virtually no resistance, but consider the electricity to cycle the liquid nitrogen and cool it down when it evaporates?
Since electrical resistance is minimal, the only cooling required once the sysem is up and running is to compensate for pressure in the Nitrogen circulation system, and for heat that leaks in. Quality of insulation is important.

Economics thus look best where electrical demand is constant. Use copper as a supplement for peak loads

IANAPBIPOOS (I Am Not A Physicist But I Play One On Slashdot)

Re:speaker wire! (1)

skaffen37 (132867) | more than 13 years ago | (#435901)

Keep in mind that you can also use the same linquid nitrogen to overclock your PC to kingdom come! ;)

Money back on Copper (1)

john_marks (135416) | more than 13 years ago | (#435902)

One of the great secrets of why companies move away from copper wires is that the sale market for it will help cover costs of the replacement. The telecom industry actually MADE money in the replacement of copper with fiber optic cable. While high temp superconducters may be a bit more pricey the cost will be offset by the resale of the old copper wire...


DOH ! (1)

Salsaman (141471) | more than 13 years ago | (#435903)

Shouldn't they be trying this out in California ?

Re:Superconducting microprocessors would be cool! (1)

evil_one (142582) | more than 13 years ago | (#435904)

Seeing as microprocessors are based on semi-conductors, which are always going to be resistant, it's just not going to happen.

Los Alamos Labs -- more than just bombs (1)

EvilDude (144717) | more than 13 years ago | (#435907)

This is quite interesting. Last summer, on my internship at Los Alamos Labs, I had a friend give me a tour of the superconductor lab. I met the guy working on this, and he mentioned this project. The only major problem is that keeping the super conductor at a low temperature is pretty expensive. But it's certainly efficient!

25000# = how many feet? (1)

BobThePalindrome (155370) | more than 13 years ago | (#435908)


"The Detroit project will replace 25,000 pounds of copper wire..."

We don't know what gauge wire they're replacing, but if its significant current carrying high tension lines then its somewhere between a few ounces to many pounds per linear foot. Likely, its 3/4 inch stranded wire, about a pound and a half per linear foot. 25000 lbs ~=~ 16666 feet, divide by three for the three phase power, my guestimate is 5555 feet of replacement. Round off to 5280, I believe these people are doing one (1) mile of cable. Gentle Readers, this is a demo project, and the Knight-Ridder reporter is trying to make it out as an industrial use.

Re:Superconducting storage loop (2)

NoNeeeed (157503) | more than 13 years ago | (#435909)

Basically the use of stored hydro is to accomodate changing loads. Most power generation systems (especially nuclear) tend to work better if they work at a constant rate. Stored hydro allows you to use excess power to pump water up the hill, which is then used to generate power in times of increased load. That means that the rate of power generation can be kept at the mean power useage (over a given period) while demand can fluctuate.

Ok so some energy is lost, but then energy is lost in all parts of the power generation and distribution system. It is cheaper and easier to run power generators at a constant rate all the time, especially nuclear.

8-fold compression... yeah right! (1)

Jage (164751) | more than 13 years ago | (#435911)

"The first invention is a method of compressing text stored in binary form, which expresses information as a series of noughts and ones, by comparing each word with its predecessor and recording only the differences between words. This compresses the data to an eighth of its normal size. "

While the information density in english text is about 0.6 - 1.3 bits per word, actually compressing data to that extent is not really possible. And even if it were and worked perfectly on english text, it wouldn't help you much - the majority of your data would be binary anyways (thus this algorithm wouldn't work). 8-fold compression is certainly not achievable in general case in practise. Most of the data volume (music & graphics files, like JPEG, MP3s and your 1337 p1r473 divxs) is already in acompressed form and you can only get a few percent off of it in the best case. So for the most of the data volume, their method would do nothing anyways.

Re:8-fold compression... yeah right! (1)

Jage (164751) | more than 13 years ago | (#435912)

Ooops, sorry, wrong article! :)

Re:Space design is not so simple (1)

Coz (178857) | more than 13 years ago | (#435914)

Silver is highly reactive - atomic oxygen (not the O2 we breathe, but the O1 that floats around in LEO) eats the stuff up, destroying its conductivity.

Spacecraft component design used to be a black art - there's now a known science to it, with educated guesses being used every few years when someone flies a new substance or technology. One of the few good things to come of the Challenger accident was that the LDEF (Long-Duration Exposure Facility) satellite got left in orbit much longer than planned. We learned a lot from what was left of the different substances that had been left in orbit.

And just because I have to borrow this tagline once:
Space is big, space is dark
It's hard to find a place to park
- Burma-Shave

Re:Supercoductors won't help that much with AC (1)

Novus (182265) | more than 13 years ago | (#435917)

> Going AC->DC->AC is getting fairly cheap these days with power electronics. Of course it would be much nicer if we just got rid of AC.

Getting rid of AC would improve Slashdot a lot, at least. B-)

Re:Supercoductors won't help that much with AC (1)

Novus (182265) | more than 13 years ago | (#435918)

Can't one compensate for the effects of inductance with a suitable amount of capacitance? I seem to recall that this is a commonly-used technique in long-distance power transmission.

This can be derived from Z^2=R^2+(X_L-X_C)^2, where X_L=2*pi*f*L and X_C=1/(2*pi*f*C) - just adjust C until X_L-X_C is zero. You should be able to find this in any decent physics book.

Re:Space design is not so simple (1)

Gordonjcp (186804) | more than 13 years ago | (#435919)

Why is silver-coated wire "absolutely forbidden" in space?
I thought it was kind of important for low-loss inductors in VHF/UHF radio gear, and spacecraft use loads of that.

Liquid Nitrogen... (4)

otter42 (190544) | more than 13 years ago | (#435920)

Working in cryobiology, a cryogenic field, I am familiar with some of the problems of liquid nitrogen.

Really, there aren't any. The stuff is insanely cheap. Like so cheap, you want to start using it as car fuel and stop drinking milk. I purchase 210L for $35.67, which works out to something around 55 cents a gallon!

Nitrogen is cheap, inert, catastrophic leaks have no effect on the world(unless it's in a closed room and someone can't get out before they suffocate), readily availalble (comprises 79% of air), and would only get cheaper to produce as power plants used more of it.

Keeping cables cool is also very easy since LN2 can be easily run through a pressurized system. There is no need to circulate the LN2 since the addition of heat will make some LN2 boil away. Simply allow the vapor to dissapate and replace any lost fluid.

The biggest problem with this project is what happens if the LN2 system fails for some reason. Fortunately, though, they will have an extremely long heads up on a failure and will be able to shut a cable down with plenty of time to spare.

On a side note, the cables use silver because it allows for proper grain growth and flexibility. Otherwise you couldn't make a cable out of the material. A big squarish chunk of it, sure, but not something long, thin, and reasonably flexible like a cable. Science News did an article on it a couple months ago.

If .. (1)

7-Vodka (195504) | more than 13 years ago | (#435921)

The cooling ever broke down.. hehehe. A thin wire carrying 150 times the power of the regular ones.. I immagine everything would be lost pretty quickly and there would be a massive blackout.

If they are deploying HT superconductors on this large a scale, what happened to all the other possible applications?

"just connect this to..."

This will make power loss in space less. (1)

linzeal (197905) | more than 13 years ago | (#435922)

We will be able to build more efficient space stations as a result of the enviroment up there favoring this technology with its severe temperatures, cool.

Re:Supercoductors won't help that much with AC (2)

ACorvus (202386) | more than 13 years ago | (#435925)

Erm, but pure inductance (or a combination of inductance and capacitance, which any transmission line has) is lossless, isn't it?

I think that the main problem with the inductance of long lines is the I and V getting out of phase, which results in less true power being delivered to the load. In addition, heavy industrial machinery is largely inductive by nature, adding to the problem. The power company monitor changes in phase when connecting stuff up, and add power-factor correction capacitors where neccessary.

The problem with saltwater may be true, in that the AC flowing in the line induces eddy currents in the partially conductive saltwater, which then will heat up, ie contributes a loss. I would think that the higher the power and line length the worse the problem.

Superconducting microprocessors would be cool! :) (1)

Junnonen (205988) | more than 13 years ago | (#435926)

Think about it: no resistance - no heat...

Re:Penis stirring (1)

DickBreath (207180) | more than 13 years ago | (#435927)

Penis stirring would work better due to more hot blood.

(I've got to get my mind back on work.)

Re:Frozen birds and burning cables? (2)

DickBreath (207180) | more than 13 years ago | (#435928)

Would it hurt the bird's talon if it punctured the cable?

I suppose this would teach the bird to stay off superconducting cables and go back to being a penis bird instead.

Re:You don't lose 10% (1)

jjsjeff (210138) | more than 13 years ago | (#435929)

You are probably right about the 10% not being lost, but eventually it will be lost combining the power lost in the wire and the power lost in the transformers. -JJS

Re:Superconducting storage loop (1)

jjsjeff (210138) | more than 13 years ago | (#435930)

When I was in high school I wrote about a certain project which the name escapes me now, but they use high pressure storage. To balance the load so that there are no theoretical peaks is that during the night this city pumps air into old salt caverns to about 1100 PSI and during the day the pressure is released turning generators to fight the peak during the day. Or if you're interested... Go Solar! -JJS

Re:I live in Detroit... (1)

jjsjeff (210138) | more than 13 years ago | (#435931)

Normally the /. effect only affects websites. It looks like now the city's power distribution will now be ./'ed :) -JJS

Re:Don't need superconductors (1)

willy_me (212994) | more than 13 years ago | (#435933)

Increasing the voltage isn't that easy. Quebec hydro uses 1MegaVolt trasmittion lines and they get some weird stuff happening. I guess you can get the occasional spontanious nuclear reaction along those lines (I'm talking about a few atoms - not a nuke..) I agree it's a good idea just not that easy to implement.


Re:Supercoductors won't help that much with AC (1)

willy_me (212994) | more than 13 years ago | (#435934)

Adding capacitance adjusts for phase shift. I remember doing all of these calculations is school - but that was 5 years ago so I've forgotten exactly how it works. As far as the actual losses are concerned, losses from inductance are greater then those from resistance on HV lines - even if caps are added to the transmittion lines.


Re:Supercoductors won't help that much with AC (1)

willy_me (212994) | more than 13 years ago | (#435935)

pure inductance is lossless so long as nothing is "leaching" the power. If what my instructors have told me is correct, there is a greater loss of energy from this "leaching" then from resistance at very high voltages. I've designed these systems on paper and to do so requires one to look at tabulated data for each size of conductor. It's very complex because there are so many different things to consider. For example, distance from the ground, distance from the other phases, .... basically lots of enviromental factors come into play. The end result, there are more losses from the "leaching" then from the resistance.


Re:Loss through inductance (2)

willy_me (212994) | more than 13 years ago | (#435936)

This works great on paper but no so in the real world. In reality, you have a rather large magnetic field changing direction at 60Hz. Now some of the energy from this magnetic field is absorbed into the surrounding enviroment - hence, is lost. Much of this depends on the enviroment but it's safe to say that anything metal will have induced currents. The end result - on HV systems most of the power loss is not due to resistance, but due to the inductance (indirectly, but still due to the inductance.)


Supercoductors won't help that much with AC (3)

willy_me (212994) | more than 13 years ago | (#435937)

When you have power distribution lines running at 500kV, there isn't that much loss due to resistance. The majority of the loss is due to inductance. In order to really benefit from the superconductor they will have to convert AC to DC, transmit in DC, then convert back to AC before being delivered to customers.

Going from AC to DC then back to AC isn't the most efficient way of doing things. It is however still done. For example, power is distributed from the mainland to Vancouver island via underwater DC power lines. I believe DC is used here because of the increased effect of inductance with the lines going under salt water.

Using superconducters is great, really, it is... But just because there is basically zero resistance in those superconducters it doesn't mean that all of our problems will be solved. Line losses due to resistance aren't the main loss when it comes to distributing power. There are also losses with the generators, transformers, AC/DC/AC converters and most importandly - inductance. It's a start, not a solution...


You don't lose 10% (3)

willy_me (212994) | more than 13 years ago | (#435938)

Sorry, but you don't lose 10% of power due to resistive losses - not even close.

First of all, most of the losses are due to inductance, not resistance (this assumes you're using HV lines - 500kV is typical.) And at 500kV there isn't that much current flowing. 50MWatts just requires 100Amps - very reasonable.

I wish I still had my college books, I could tell you exactly what the losses would be. (I graduated in power systems electronics - this is what we did.) Unfortunately I don't - but I assure you that resistive losses are not the main source of loss from a high voltage power distribution system.


Re:Frozen birds and burning cables? (1)

Kierthos (225954) | more than 13 years ago | (#435945)

Yeah, if you're slick enough and careful enough, you can take a shot glass of liquid nitrogen, pour it into your mouth, and exhale the nitrogen gas without hurting yourself. But you also have to be damn lucky too... I would suggest never ever trying this, no matter how cute he/she is or how much you want to impress her/him.


Re:This doesn't sound all that useful (1)

Kierthos (225954) | more than 13 years ago | (#435946)

Okay, you have V=IR, where for those who don't know, V = voltage, I = Amperage, and R = Resistance. Bare copper wire with an AWG of 4 (diameter of between .2023 and .2063 inches) has a nominal resistance of .2485 Ohms and a maximum resistance of .2534 Ohms per 1000 feet at 20 C.

What this means is that at nominal conditions, for every 1000 feet of bare copper wire, you lose about a quarter Volt per Amp of power you pump through the lines. Insulation between wires keeps them from melting together as the resistance heats the wires, and keeps the power loss due to resistance lower.

If these high-temperature superconductors reduce the power transmission loss (the resistance that a superconductor offers is practically zero, but not exactly zero) which they should, then more power will be available for use as you're not losing as much.

Will your power costs drop? Logically, they should, but logic has little to do with power company rates.


Re:Superconducting storage loop (1)

Kierthos (225954) | more than 13 years ago | (#435947)

No offense, but unless I missed an important lecture in thermodynamics, how can they hope to make money from this? It takes more power (which equals money in the eyes of the power companies) to pump water uphill then they can get from it going downhill...

I mean, the first two Laws of Thermodynamics can be summed up as:

1) You can't win.
2) You can't break even.


Re:Frozen birds and burning cables? (1)

Kierthos (225954) | more than 13 years ago | (#435948)

Nope, but I saw one guy stir a small beaker of the stuff with his bare finger and not get hurt. Of course, then he started dipping ink pens in the beaker and shattering them. Cleaning up that mess wasn't fun...


Re:This will make power loss in space less. (2)

Kierthos (225954) | more than 13 years ago | (#435949)

Well, it all depends on where in space you are. An object that both absorbs and emits perfectly, put at a distance from the Sun equal to that of Earth, will stabilize at a temperature of about 280 K or 7 C. If it's shielded from the Sun but exposed to inter-planetary and inter-stellar radiation, it reaches about 5 K or -268 C. If it were far from all stars and galaxies, it would come into equilibrium with the microwave background at about 2.7 K. Now, the last is not feasible at this time.

Depending on how it is constructed, you'd have to use a lot less energy to keep it cool then a similar system on the ground, but there you go...


Wow! Awesome conductivity, but... (1)

James Foster (226728) | more than 13 years ago | (#435950)

Watch out electricians in Detroit... one mistake now and you're toast for sure!!

Michigan: first in power, last in online anonymity (1)

objekt (232270) | more than 13 years ago | (#435952)


Oh Joy! (1)

selan (234261) | more than 13 years ago | (#435953)

Their discovery caused so much excitement among scientists that it spilled over to the public and politicians.

Sheesh, this must really be a big deal, if even the politicians support it. *grin*

Re:Frozen birds and burning cables? (1)

Beowulf_Boy (239340) | more than 13 years ago | (#435955)

Are you the dude that swallowed it?
I know he's on Slashdot somewheres.

Newsflash!! (1)

RapaNui (242132) | more than 13 years ago | (#435957)

REUTERS: A new room-temperature superconductor has been developed by a US university.
"It's a breakthrough in electricity transmission" says it's creator, Dr IM Tryntafulyu,
"We've been testing it in outdoor transmission cables on our campus, and it seems to be working fine"
reported Dr Tryntafulyu, from his laboratory in Pt. Barrow, Alaska.

Re:Cable is light... (1)

ConsumedByTV (243497) | more than 13 years ago | (#435958)

1024*2 is 2k, hence y2k... get it?

Fight censors!

Superconducting storage loop (1)

ScottBob (244972) | more than 13 years ago | (#435959)

Didn't someone once propose that electricity could be stored in huge loops of superconducting wire in underground tunnels as big around as particle accelerators? Power stations would charge them up at night when the load is low, then the electricity would continue to circle inside indefinitely until tapped, such as peak load during the day. This seems to be one step closer to that idea, as the original idea was to use copper wire and liquid helium (expensive!!!)

Anyway, it would seem to be prohibitively expensive to retrofit the electrical grid by building what basically amounts to be a liquid nitrogen pipeline with ceramic rods inside (very brittle too at those temperatures, no doubt.) But then the liquid nitrogen on the receiving end could be used in compressed air powered cars, etc., thus solving two infrastructure problems with one idea...

not getting this... (1)

DaKaktus (245437) | more than 13 years ago | (#435960)

"made from a high-temperature superconducting material called BSCCO (pronounced bisco)."

Most of the energy lost from transmitting electricity is through heat loss, so, if its a "high temperature" cable wouldnt that imply that it is actually losing more energy than it was before?

I live in Detroit... (2)

The Blackrat (255469) | more than 13 years ago | (#435962)

And I can say, with great precision, that the cables will be stolen and sold at a pawnshop.

Re:Forgot URL. (1)

egommer (303441) | more than 13 years ago | (#435968)

Sorry, forgot to include link.

Re:Savings is in power loss (2)

egommer (303441) | more than 13 years ago | (#435969)

One of the bigest advanatages of HTS Transmission is a not only less resistance but lower power operating temperatures. This is not a direct affect of the Nitrogen cooling. When the Material is operating at superconducting temperatures the lack of resistance creates absoluty no heat in transmission. Once the temperature is reached it is easy to maintain. The transmission of power through the cable has no affect on core temperature. Very little energy is needed to keep it in a supercontuctive state once it is reached. burying the cable will assist in prviding a natural and cost effective way of assisting in ambient temperature degridation. Here is a company that was the first to have an operational prototype. picture included. Intermagnetics

Space design is not so simple (1)

Caid Raspa (304283) | more than 13 years ago | (#435970)

The idea of replacing heavy cables with light superconducting ones sounds great for space applications, but thermal problems are only one thing in spacecraft design. This solves those quite well. A few others do not sound that easy:

Radiation is a big problem in space. A lot of materials can not be used in orbit because they deteriorate very rapidly when getting a large dose of high-energy radiation. (The same applies to e.g. nuclear reactor design.)

Maintenance: if a copper wire or whatever they are using now breaks (space debris collision etc.), it is quite easy to fix. Just turn off voltage and replace the broken part. These superconducting cables are made of granules in a tube. Then, you would have plenty of superconducting granules floating around, short-circuiting everything. Nice?

Vacuum: Out-gassing the tube with little granules inside sounds a little more difficult than a normal wire. How does the ceramic stuff and the coating behave in vacuum?

Attitude control and orbit: the spacecraft would have some additional constraints as the side with superconductors should be kept out of sunlight all the time. This is possible, and done often, but not always, as e.g. ground links give other constraints.

I think silver-coated wire is on the list of absolutely forbidden materials in space, so the design they are using is not directly applicable.

Re:Frozen birds and burning cables? (1)

ooze (307871) | more than 13 years ago | (#435971)

Guess they'll need a circulating supply of liquid nitrogen. So the electric infrastructure will be some isolated hose. And I think they'll have to bury it, as a broken hose in the earth will freeze ground life and make it hard to dig a hole to reach the defect, but a broken hose in the air will cause serious harm to any passing creature. I dont like the idea of trickling liquid nitrogen above me.

Re:Pronounced (1)

vidarh (309115) | more than 13 years ago | (#435972)

It's normal for the "owner" of an acronym or invented name to dictate the official pronounciation. And it's common for abbreviations to get it's own pronounciation, if there are any reasonable alternatives that "sound good". Take TeX, for instance, or SCSI. And in this case, pronouncing it bisco is pretty reasonable.

Re:Superconducting storage loop (2)

vidarh (309115) | more than 13 years ago | (#435973)

They can make money from that if they have a power plant that can provide the same output with minimal variable cost 24 hours a day. At night they will likely not use their full capacity. By using the surplus power produced during the night to pump water into a reservoir, heat up a well, or do anything which will allow them to produce more power at daytime, they may be able to improve throughput during the times of day when the power drain is highest.

It's not about increasing power production, but about efficient short term storage.

Well... (1)

rlanctot (310750) | more than 13 years ago | (#435974)

I guess we don't have to worry about global warming any more...

Re:not getting this... (1)

xeeno (313431) | more than 13 years ago | (#435976)

Resistance in the wires is what causes the heat. Superconducting wires imply no resistance, therefore, no heat.

Re:Superconducting storage loop (1)

FlashfireUVA (315550) | more than 13 years ago | (#435977)

Kierthos, you forgot the third Law ...

The Laws of Thermodynamics can be summed as:
1) You can't win.
2) You can't break even.
3) You can't leave the game.


The only reason we have AC... (1)

kghougaard (315693) | more than 13 years ago | (#435978) because of the transmission lines. Power plants could (easily?) produce DC power, and allmost all power consuming equipment requires DC, which we supply with a huge amount of AC/DC converters - which causes large losses of energy. Most AC/DC converters are optimized for one amount of power, but are used also to deliver the power for standby-operations (TV/VCR/COMPUTER/STEREOS), which is VERY uneffecient. So lets get rid of AC power - its easy... it will only take a LOOONG time, and cost an unbelievably large amount of money. (This means that is is unfortunately not possible ;-) By the way - Here in Denmark - on the small island in Copenhagen called "Amager", the worlds first practical use of superconducters as power distribution cables, are allready being installed. The testing phase is finished, and they are currently being installed. So actually - old news ;-) Kristian
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