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Superconducting Cables To Carry Power In Detroit
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.
Cable is light... But liquid nitrogen cooled? How would that react under (summer heat, nuclear war, y2k, world war 3)
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.
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.
I'm trying to figure out who the major players in the comercial superconductor game are, and i'm curious if any /.ers have come across who they're buying the cables from and who's going to be maintaining them...
slinted (ofthehillpeople)
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?
nature already delivers free power to each and every home in the USA. It's called sunlight.
But I guess if we learned to take advantage of that, then there would be no use for bloated inefficient electricity utilities.
These are my friends, See how they glisten. See this one shine, how he smiles in the light.
Just do away with the power company altogether. No reliance on the power grid or power lines when you generate your own electricity more efficiently using a fuel cell. See www.plugpower.com
You've applied this equation incorrectly. Yes, P=V^2/R, but V is the voltage difference between the potential at one end of the wire and the potential at the other. If the power plant is producing 500KV, and the potential on the wire when it reaches the transformer is 499 KV, then you're only loosing 1KV^2/1Ohm, not 500KV^2/1Ohm, which would be the total power used including line loss plus the power used by the consumer which is not inefficiency.
A cool use for high-Tc superconductors :)
What part of "A well regulated militia" do you not understand?
I have to love the obscure reference to :)
Ringworld.
"think of it as evolution in action"
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...
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.
no, because YOU CAN'T DIVIDE BY ZERO!
a number divided by zero is NOT infinity, it is undefined.
</rant>
Did you mount a military-grade, variable-focus MASER on an unlicensed artificial intelligence?
DETROIT, Michigan (Reuters) - 2 members of a work crew were simultaneously fried to a crisp and frozen solid today after their backhoe hit the new superconducting power line that was recently installed by Detroit Edison.
The new superconducting line carries power for half the city of Detroit, and that half of the city immediately blacked out after the superconducting line was cut. Officials have given no estimate of when power will be restored, but say they are "working on it" and additionally commented that "this superconducting line is a bitch to work with".
The shift supervisor was on site at the time of the accident. When asked about the accident, he commented "I'm just glad I was here, because they'd have a really hard time identifying the bodies otherwise". When asked how the accident happened, he said "we hit all sorts of lines with our backhoe all the time, but most of them are phone and data lines, so it's rare that there is a safety issue". Officials at Detroit Edison confirmed this, saying "most of the lines we hit belong to UUnet. We're proud to be helping to give those bastards a bad reputation".
Family members of the deceased could not be reached for comment.
--
Use 'slashdot stuff' in the subject line in any email you send me if you want to get past the spam filter.
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.
Finally! A year of moderation! Ready for 2019?
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.
Finally! A year of moderation! Ready for 2019?
--
--
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.
Need a Python, C++, Unix, Linux develop
I used to live in Detroit and every year would see a lot of downed power lines.
They don't explicitly explain (at least in this article) what effect the new cables will have on the prevalence of downed lines. However, they do mention that they're more brittle so unless they're much stronger, it seems as though this problem will get worse.
Am I correct?
stay frosty and alert
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?
I Don't Work Here
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.)
All superconductors have a characteristic
called critical current. Go above it and
superconductivity is destroyed. The lower the
temperature, the higher the critical current.
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.
Thank God. And just when it looked like Detroit was going to sink into the ocean under its own weight.
The opinions stated herein do not necessarily represent those of anybody at all. Deal with it.
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.)
Fissure erupts, turns citizen into pillar of salt! Story at 11.
(so what's ksu's analogue to ku's kulua?)
Things that can make logic gates:
Vacuum tubes
Transistors
Relays
Streams of water
Ropes and pulleys
Brain cells
If you can create an intelligent out of semicondutors, then you can do it with a sufficiently complex plumbing system.
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!
It's not that the single electrons 'don't collide': coupled pairs of electrons are bosons, since spin 1/2 cross spin 1/2 yields either spin 1 or spin 0: both of which are bosonic.
You're probably familiar with the Pauli exclusion principle for electrons - this says that no two electrons (fermions) can occupy the same quantum state. This is because electrons, having spin 1/2, are fermions, and obey Fermi-Dirac statistics (interchanging fermions changes the sign of the wavefunction).
Bosons don't have a Pauli exclusion principle - interchanging bosons doesn't change the sign of the wavefunction at all, and so the number of particles which can occupy a state is unlimited.
Thus, imagine a pair of electrons in a material- nothing is stopping them from radiating their energy away and settling into the ground state- it doesn't matter that there are other pairs of electrons there, since a pair of electrons is a boson. They then settle into the ground state - the lowest energy state.
Now, you've got a curious situation. The electron pair is propagating through the material since there's a potential well - there are particles which they COULD scatter off of and lose energy - but they're in the ground state - they CAN'T lose energy, so they CAN'T scatter. It's not that the electrons don't collide 'as much': ideally, they don't collide at ALL - resistance zero.
As for the 'electron-pair' waves: the idea of waves and particles being separate things is a classical idea: Nature doesn't quite agree with that. Particles are waves, waves are particles, it's all the same bloody thing. Calling them 'electron-pair' waves is fine: calling them 'electron-pair' particles is also fine. de Broglie matter waves are also a semi-classical idea: halfway between QM and classical mechanics - it would be a good thing to abandon that idea, and just accept that fundamentally, all matter has a wavelike nature.
For a good start in QM, read D. Griffiths "Introduction to Quantum Mechanics": Griffiths's texts are usually quite amazingly good at allowing students to actually understand the physics of the situation. Getting rid of classical intuition like "physical location of a particle" and "momentum of a particle" and "particle" in general is a good thing to learn as soon as possible if you are interested in higher physics.
There are other processes in superconductors which do cause resistance-like effects, but fundamentally, the superconductor itself has zero resistance - you might have things like thermal resistance, or 'magnetic resistance', or impurity resistance, but the superconductor literally has zero resistance, almost (note almost) by definition.
No, actually, impedance is a 'resistance' to current flow due to a changing magnetic field, which induces an opposite EMF in the circuit. Physically, the best analogy would be if you imagine resistance to be traffic slowing you down in a car: impedance would be similar to something like bad gas in a car reducing the amount of power available, or going up a hill (going up a hill is a weak analogy, but it has a strong parallel in the whole EMF/potential well thing).
Argh, argh, argh. Somehow hit 'submit' before I was finished typing. How aggravating.
It's true - there is no resistance in a true superconductor, isolated from all else, with an isolated current inside of it. However, place that superconductor in a circuit, and many various issues will arise, again, especially in T2 superconductors which will admit magnetic fields through their volume.
Still, the best way to describe it is to say that the superconductor has zero resistance, and that effectively you have additional objects introducing mitigating effects.
The first superconductor wasn't lead - distinctly not! - it was mercury. 1911, Heike Kammerlingh-Onnes, using liquid helium to cool mercury below 4K.
Actually, no... its resistance does drop to zero, literally. However, the behavior becomes 'curious' when you actually try to drive current through it - especially since this is a T2 superconductor,which means that it forms magnetic whorls at any non-zero magnetic field. As you know, a current creates a magnetic field, and so you get a sort of 'balance' between the amount of current you can drive and the maximum field that the superconductor can support. If you try to drive more current than that, then you will begin to drive the substance out of a superconducting state.
Is it a resistance? Well, no, distinctly not - it's not linear in voltage, for one. It could be thought of as an 'effective' resistance, but it's not resistance.
Incidentally, it's very dangerous to simply show "Look, it's infinity!" and use that as a disproof - several things in nature are extremely curious and are literally infinity: take for instance a superfluid, which has, literally, zero viscosity, or an electron, which has (as far as we know...!) zero volume. Dividing by either of those things would tend towards infinity - the fact that it does not actually get to infinity simply means that another process begins to dominate and damp the previous one.
"High temperatures", like 22 degrees C? I don't think so. Not that high yet.
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.
-- Don't believe everything you read, hear or think
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 ?
Who would you trust to do research on this stuff, you (someone who apparently has _some_ knowledge regarding this stuff) or Rob and Hemos? This is what
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.
Good point. Maybe they should switch to DC for these lines. Then there would be effectively no inductance losses, either.
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).
Ohm's Law only applies to what are called Ohmic resistors. Some metals are generally Ohmic; others are generally Ohmic but only at particular temperatures. Some substances are not Ohmic at all, such as the YBCO superconductors I worked with as a research aide at the Texas Center for Superconductivity.
For comparison: Ohm's Law generally applies to copper, no matter what the temperature is. Ohm's Law stops applying to aluminum once you cool it to about 4K.
Remember: Ohm's Law is a macro-scale observation, and superconductivity is a quantum-scale event. At the quantum level, all sorts of strange things happen that are totally contrary to our macro-scale observations. The Einstein-Bose Condensate is a great example, as is superfluidity in liquid helium. (Anyone who is not utterly shocked and amazed by superfluidity apparently hasn't seen superfluids before.)
This is now my sig.
The abbreviated Laws of Thermodynamics:
1)You can't win.
2)You can't break even.
"We all do no end of feeling, and we mistake it for thinking." -Mark Twain
> 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!
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.
I mean seriously, they need to implement this right away if possible. They say we're going to have a power crisis for the next 2 years until they start building new power plants or come up with a better idea. Think how much power they would save if they used superconducting cables that could be put towards the larger power pool.
http://www.livejournal.com/users/cixel
No, no, no!
1) You can't win.
2) You can only break even on a cold day.
3) It never gets that cold.
"I'm an old-fashioned type of guy. I worship the Sun and Moon as gods. And fear them."
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!
//rdj
No one can understand the truth until he drinks of coffee's frothy goodness.
--Sheikh Abd-Al-Kadir, 1587
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.
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.
Lack of resistance (up to a point), and greater over-all power capacity.. The article says 150 times, meaning if we had 50 or so separatly maxed out copper cables running at a constant voltage, we could combine them into 1 (with the same voltage or current (or combination of the two)). Traditionally if you wanted greater power capacity, you'd do what you needed to the wire to allow higher and higher voltages to minimize the current. Higher voltage usually requires greater separation between lines (since there is significantly enhanced potential for shorts). So by not _having_ to up the voltage, you can keep lines closer together.
So the benifits are power efficiency, and that you need less total physical stuff to get the power downtown.
-Michael
-Michael
...to 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...
-- You can't idiot-proof anything, because they're always coming out with better idiots.
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.
./ 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.
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
Sigged!
Why don't we use them then?
Just follow the fucking link.
Sigged!
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).
-NOC Monkey (OOK!) Experience is what allows you to recognize a mistake the second time you make it.
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.
My Other Computer Is A Data General Nova III.
How would a superconducting cable stand against fiber?
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.
The higher, the fewer.
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.
The higher, the fewer.
I hope they have considered the risk of nitrogen leaks in the confined spaces of the tunnels. Even a relatively small leak could quickly push out the oxygen and result in the death of anyone who happens to be nearby.
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).
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.
- Sig
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
-- I wonder which will go down in history as the bigger failure: the War on Drugs or the War on Filesharing
in the UK Maplin magazine recently about this. They have no web site, but baically the cables will run underground (no fried birds).
The cables are (I think) manufacured by Pirelli and consist of a central LN2 tube surrounded by the conductor, then several layers of insulation. This is (apparently) the most efficient way of doing things
True, but the generators generate AC which would have to be converted to DC which would constitute a loss. Just think why your PC's power supply has all those fans and cooling vents.
And the reason why generators generate AC and not DC is the way they work. The energy comes from spinning a loop (area A) in a magnetic field (magnetic induction B); the voltage is related to the angle between the loop and the magnetic flux density. Thus, a sinewave.
Hm? This is most interesting then.
You know, this R != 0 is not my invention, I heard it somewhere. It was offered with an explanation that the reason that the resistance drops dramatically is that under some circumstances, electrons form up pairs, which don't collide as much with the material as single electrons would. This sounds quite reasonable to me, but then again, it boils down to quantum mechanics I'd suppose where common sense just aint enough.
A quick search on google gave me this page, which uses the term "electron-pair" waves. This particular term sounds like quantum mechanic atomic model. Would this mean that electrons in a superconductor should be considered de Broglie matter waves rather than actual particles?
This is very interesting. I tried to look up further with google but no luck so far. Pointers would be appreciated.
And the notion about R = U/I.. as someone mentioned, it applies only to ohmic resistors which superconductors definately are not. Shoot me in the head if I make that mistake again. I blame the lack of caffeine on that one :-)
Resistance R: p = 1.678E-8 Ohms/m for copper
l = 10000m for instance
A = 1.0 cm2 = 1E-4 m2
R = p l/A = 1.7 Ohms
Inductive reactance XL:
f = 50 Hz
û = 50kV
î = 100A
h = 10 m (height above ground)
r = 0.0056 m (wire radius)
u0 = 1.25664E-6 N/A^2
ur = 0.99990 (copper)
L = l * (u0*ur)/(2 pi) * cosh^-1 h/r = 0.016 H
XL = 2*pi*f*L = 5.0 Ohms
Comparing R = 1.7 Ohms and XL = 5.0 Ohms proves your point.
you think that stuff's bad -- check out sulfate of thanatol.
The Autonomous Cow. Moo.
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.
steveha
lf(1): it's like ls(1) but sorts filenames by extension, tersely
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.
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.
oojah
Do you have any better hostages?
The first link is slide from a Brookhaven talk. Not much useful info here, and the picture doesn't match what the other links describe. The entire slide show is fairly interesting, though.
The second link is PDF whitepaper discussing the commercial production of such cable. A great read, if you have the time to wade through it.
The third link is an article from the Nov. 18, 2000, issue of "Science News" on the same subject as the Knight-Ridder article. Much more technical details.
Nothing for 6-digit uids?
If the current in a superconducting wire reaches a high enough level its magnetic field will destroy the superconductive properties of the wire, so there is an maximum current possible in the wire.
For A/C currents while the Superconducting wire has zero resistance, it does have some impedance which also limits the maximum current but in a way that doesn't dissapate energy as heat.
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).
-Wallace
"I am Jack's complete lack of suprise." -Fight Club
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)
Ben Masel: 51,282 votes for US Senate in the Wisconsin Democratic Primary
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...
=JM=
Your global village idiot!
Shouldn't they be trying this out in California ?
Seeing as microprocessors are based on semi-conductors, which are always going to be resistant, it's just not going to happen.
---
Desperation is a stinky cologne
That's interesting. I'll probably look into it further, but I do have one question: Why don't we use them then?
---
Desperation is a stinky cologne
You certainly are touchy, arn't you?
First, I did follow the link.
Successful test of a superconducting ATM prototype switch
This is not production. We are not using them.
Since you seem to be so smart, why don't you explain to my why this is?
---
Desperation is a stinky cologne
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!
"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.
Peace.
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.
Paul Leader
Knight rider carries superconducting cables to Detriot? Wow, it's good to see that Hasselhoff found new work after baywatch got canned last week...
Slashdot: come for the pedantry, stay for the condescension.
"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.
--
Does this mean that the power won't go out everytime mother nature sneezes ? Its pretty fscking annoying. Detriot Edison has got to have the worst service I have ever seen. I sure hope this improves it.
until (succeed) try { again(); }
until (succeed) try { again(); }
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
I love vegetarians - some of my favorite foods are vegetarians.
I say "blasting cap" because I recall a guy I used to work for in the radio industry, who'd once worked in quarries... to detonate explosives, they'd run about 1000 times more power through a transistor than it was rated for, and the ceramic would heat, expand, and then explode, triggering the real explosives... this is the same guy who showed me diodes from lightning-struck equipment that let current flow freely both ways.
I love vegetarians - some of my favorite foods are vegetarians.
I wonder how well these cables with stand up to typical summer conditions here in SE michigan. Not the hotter than hell / mid 50's for high's summers. No, i want to know how well these cables will withstand the three or four major thunderstorms we get each year. How easy are these cables to re-string? Are poles / towers carrying these cables more prone to lightning strikes? What happens to a broken cable? does the Liquid nitrogen just evaporate leaving a super-hot super conducting cable?
I'm sure these things have been brought up and adressed somehow, i just dont want to see cool technology writen off after the first major thunderstorm turns expensve new wiring into a useless coil wrapped around a pole.
--
There are some people that if they don't know, you can't tell 'em.
> 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-)
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.
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.
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.
www.eissq.com/BandP.html Ball and Plate System. Amuse your friends. Crush your enemies.
If they are deploying HT superconductors on this large a scale, what happened to all the other possible applications?
"just connect this to..."
BZZT.
Liberty.
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.
An Education is the Font of All Liberty
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.
-- Sig Sig Sputnik
Think about it: no resistance - no heat...
Penis stirring would work better due to more hot blood.
(I've got to get my mind back on work.)
I'll see your senator, and I'll raise you two judges.
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
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! http://www.engg.ksu.edu/solarcar -JJS
Normally the /. effect only affects websites. It looks like now the city's power distribution will now be ./'ed :)
-JJS
It happens to be K-SLUG (Kansas State Linux Users Group) I happen to be on the KULUA listserve as well. Kulua's members are mostly Lawrence/KC people but there are a few of us Manhattanites on the KULUA listserve. -JJS
Willy
Willy
Willy
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...
Willy
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.
Willy
Actually, "magnetic resistance" is called Impedance isn't it? but if the superconductors are separated so that their magnetic fields don't interact then the practical impedance should be a "virtually null" value. Quantum theory aside, it has been proven empirically that there is no appreciable resistance in a superconductor. Even the first superconductor (a lead donut in liquid helium i believe) was able to keep a current that had been applied to it in Sweden, running at basically the same value when the donut was taken to England and the current was measured. all told I think that it will be a very interesting civil engineering experiment.
"Laws are like sausages, it is best not to see them being made" Otto Von Bismarck
Hey! at least I got the liquid Helium right! thanks for the correction though, I was thinking about a demostration of superconductivity that took place at a science exhibition in England. Same scientist I think.
"Laws are like sausages, it is best not to see them being made" Otto Von Bismarck
I was reading the last chapter of an engineering textbook the other day --sorry, forgot the reference info-- that mentioned HV long distance DC transmission as an often overlooked bit of technology. The author claimed that the real problems with electrical power sharing across continents was not the any technological limitation, but a lack of political will to share electrical generator capacity between nations along with the fact that power plants are built to such a scale that most of the power is consumed within a fairly local region. According to the author, this had little to do with line losses or the inability of conventional metals to carry large currents over long thousands of miles.
I mentioned this to my father who is quite excited about superconductor technology and he said that was nonsense, echoing a lot of the posts I've seen here today. But I wonder if this textbook might not have had it right.
This same book said that there was no reason to think that conventional coal and oil fired powerplants couldn't be made much more efficient if they were scaled up many times larger than the current standards. According to this book, the reason we've settled upon powerplants of the size and efficiency that we have is that the individual components are as large as the transportation infrastructure can support for manufacture and maintenance. I thought this was a fascinating observation although I don't know if it's accurate or not. Sure does have a ring of truth to it.
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.
Kierthos
Mr. Hu is not a ninja.
Watch out electricians in Detroit... one mistake now and you're toast for sure!!
I live in Detroit, and the main thing I want to know about it is: does this mean our electric bills will go down?
No data, no cry
nt
-- Boycott Shell
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*
Loss can be due to resistance or it can be due to reactance, capacitive and inductive. Inductive reactance is directly proportional to frequency and capacitive reactance is inversely proportional to frequency. Thus, one can dircetly offset the other. At zero frequency (DC) a pure inductor has no reactance and a perfect capacitor has infinite reactance.
The reason capacitive and inductive reactances can cancel one another is that they are vector quantities. Capacitive reactance causes current to lead voltage in phase by 90 deg. and inductive reactance causes current to lag (follow) voltage in phase by 90 deg. By using vector addition, capacitive reactance and inductive reactance can cancel each other out. i.e. 10 ohms of pure capacitive reactance added to 10 ohms of pure inductive reactance will result in a net reactance of 0 ohms. This is because both quantities are vectors which have a magnitude and angle component which must be accounted for when adding them together.
In the real world, power factor correcting capacitors are used to "cancel out" the effects of inductive loads on the power grid. (These inductive reactances can be due line inductances or inductive loads like air conditioners and motors.) This means the capacitors effectively supply VARs to inductive loads while generators provide the Watts. (See the aside on power below) Power factor is the angle between apparent power and real power. The capacitor ends up making the circuit look closer to completely resistive, "correcting" the power factor back to 1.0.
Interestingly enough, some types of line construction, like that used for 765 kV, can be very capacitive. (Think of large surface area over a ground plane.) This can really help on hot days when everyone is running their a/c, but this can actually cause system voltage to rise when the inductive load is low. Because of this, shunt reactors may need to be switched in on long 765 kV lines to keep the system voltage from getting too high.
Superconducting lines are interesting because they produce no heat. Heat is one of the limiting factors of power transmission lines. Too much current causes the lines to stretch (expand) and break. (The capacity can be further constrained by power system dynamics and stability which I don't understand enough to even begin to explain.) Even though a line may have little resistance, driving 1000 MW or real power through it will generate a lot of heat, even if it's only 10 ohms. Take that down to 0 ohms, then you don't need to worry about heat.
As an aside, many folks don't realize is that power (more correctly apparent power) is made up of two components. There is the "real" power measured in watts and the reactive power measured in VARs. Some folks call reactive power "imaginary" power since it falls on the imaginary axis of the complex number plane, but make no doubt about it, there is nothing imaginary about reactive power; it must be produced, transported, and delivered by the power company. The apparent power of an AC circuit is measured in VA (volt-amps) and is the magnitude of the phasor representation of the real and reactive components.
Another way to look at it is that apparent power is that drawn by the total impedence of the load. Just like apparent power is made up of real and reactive components, impedence is made up of (DC) resistance and (inductive) reactance. Resistance is responsible for the real power drawn by the load, reactance is responsible for reactive power drawn by the load. So you can look at the losses and associated powers individually (resistance/real power & reactance/reactive power) or as a vector sum (impedence/apparent power).
Since reactive power is a somewhat difficult concept to grasp, some folks like to think of it as the energy required to magnitize the coils of a transformer or motor as opposed to the energy required to do real work like turning a shaft or lighting a light bulb. You don't get anything done by simply magnetizing the coils, but the energy can't get transfered without that process.
--zawada
In Soviet Russia, the Beowulf cluster imagines you!
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.
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...
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?
"Before you critisize someone walk a mile in their shoes, that way when you do critisize them you'll be a mile away and
The article says the cables are cooled with liquid nitrogen. But how? Does the liquid nitrogen flow down the center of the cable? It seems that the logistics of cooling would be a major drawback.
I watch Brit Hume on Fox News
And I can say, with great precision, that the cables will be stolen and sold at a pawnshop.
But i recall that IBM had made a discovery of High Temp superconductivity in the 80's and won a noble prize for it ( 1988 i think ).
In 1994 or 1995 they announced that they had receached 220 degrees below zero ( which I think is hotter than these cables).
Does anybody know who are the inventors or sponsors of this project besides the power company. It's interesting to note that this small advancement could forever change the way of power distribution.
Just in NYC all the power cables are laid underground. Think of all the space savings. If there ripping up the streets or relaying cable that would mean that there should be project along these pipe to place more fiber ( it's easyer to pull groups cable than just 1 strand ).
Just think, Power companies ( common carriers ) would now be in the data transmition field
ONEPOINT
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Sorry, forgot to include link. http://www.igc.com/td/12_5kv.htm
Two Towers-Two Worlds.One seeks triumphs and freedom for man.The other deems man unworthy and wrecks them.
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.
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.
I guess we don't have to worry about global warming any more...
...is 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
He, who dies with the most toys, wins