Superconducting Power Lines
- Thread starter Goosemaster
- Start date
That's interesting, but we won't be moving away from 3-phase power for many generations. I wonder how these will work with all the reactive power coming back to the distribution station. That alone would cause it to act like a normal copper line. They're talking about using a single phase, so I guess they could use a normal return line. Either that, or the providers will require industrial complexes to be load matched. Maybe I'll look more into it. I know this was discussed years ago, but I had no idea they were already implementing it. I hate dumbed-down articles. 
frostedflakes
Diamond Member
- Mar 1, 2005
- 7,925
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The photo with the article shows the three legs of the three-phase power circuit.Originally posted by: MoMeanMugs
That's interesting, but we won't be moving away from 3-phase power for many generations. I wonder how these will work with all the reactive power coming back to the distribution station. That alone would cause it to act like a normal copper line. They're talking about using a single phase, so I guess they could use a normal return line. Either that, or the providers will require industrial complexes to be load matched. Maybe I'll look more into it. I know this was discussed years ago, but I had no idea they were already implementing it. I hate dumbed-down articles.
You mention going from three-phase to single-phase power. This application of superconducting has nothing to do with the radian offset of the power arrangement.
What you state would violate all of Tesla's genius.
Edited: The only reference I saw in the article was to state that, "A single superconductor running underground can take the place of a nest of conventional copper lines strung overhead.", which has nothing to do with three-phased power.
Originally posted by: frostedflakes
Neat, but I'm still waiting for room temperature superconductors.
That alone would solve a big part of our energy crunch.
PottedMeat
Lifer
- Apr 17, 2002
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Wonder how much LN2 they need to keep that thing going. Maybe they have one of those on-site generators or something.
RideFree, you may be correct, but that sentence was worded poorly. Maybe I didn't read it correctly at 3 in the morning. I was thinking they were using 3-phase now because of the way loads are setup, but they were moving to a single phase in the future. Either I read too much into it, or the writer has me imagining things.
I was thinking they were using 3-phase now because of the way loads are setup, but they were moving to a single phase in the future. Either I read too much into it, or the writer has me imagining things. Just to quell any confusion, this is 3 phase, superconductors have nothing to do with the number of phases used. That said, I would have to think that the cost of the coolant must be pretty high. I mean in order for this EVER be economical the energy used to cool the lines has to be less then the energy that would otherwise be lost in the lines.
Not really anything all that new here, the same company also makes superconducting synchronous condensers which are installed in various places.
Not really anything all that new here, the same company also makes superconducting synchronous condensers which are installed in various places.
Cogman
Lifer
- Sep 19, 2000
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Humm, maybe we should make LN2 powered cars
after all, you would just need to heat the stuff up and make basically a steam engine. (yes, I know that the power would be pretty crappy and that heating LN2 probably doesn't pack as much of a punch a gasoline)
They don't actually "use" any liquid nitrogen at all. It is a closed system and is cooled by a cryocooler (basically a very good refrigerator). Moreover, superconducting power lines are very well insulated so keeping them cold does not require much energy (you still "gain" energy compared to resistive losses in copper wires).
Nowadays cryocoolers are small, reliable and -if you only want to cool something down to 77K- quite cheap. Pulse tube coolers have been used to e.g. cool superconducting filters in base stations for cell phones for a few years now without problems, they can run for years
without maintanence.
But it is one thing to cool down a small area and another to cool down a 100 mile power line, you would need alot of coolers and if anyone screws us the line is out of service. Not to mention the fact that you would need more towers since the lines are heavier and that costs alot of money too. Or else you run the lines underground, but then you have a high shunt capacitance which will cause larger losses.
Firstly, the main market for superconducting cables is power transfers within cities where they will be used to upgrade existing underground networks that are running out of capacity (and digging bigger tunnels for more copper lines in a city is very expensive); i.e. all the lines will in the ground and they are more or less "drop in replacement" for existing copper cable.
Secondly, you do not need a lot of coolers. The insulation is so good that is the lines do not actually need much cooling (remember that there is no power dissipation in these cables, if the insulation was perfect you would not need any cooling at all) and they will work for a while even if a cooler shuts down.
Also, the lines are actually not very heavy. Most of "cable" is actually insulation and conduits for liquid nitrogen; the superconductor itself is quite thin.
Edit: Note that this is the first commercial installation, i.e. with a paying customer as opposed to a R&D project.
Superconducting cables have been tested in real networks for a number of years. There have been a few projects in the US, a couple in Europe (one cable was used for a couple of years in Copenhagen) and some in Japan.
Some big cable companies are also starting to get involved and are starting up production, at the moment mainly for R&D but they are clearly in it to make money.
OK, well I see where there might be a limited market for this sort of technology inside big cities, that not normally where I think of high voltage power lines being, but obviously they are needed there too. But I still think it will NEVER be economical (or at least 50+ years) for this to actually be used in a widespread fashion for moving power across the country so it can certainly be an economical item, but only in a niche market.
This is exactly the point I was trying to make. These cables aren't useful for supplying electric cars to any great extent because you would need long above ground cables if you wanted to beef up the entire grid and these can't help you there. Copper is expensive for sure, but steel prices have been rising a good deal also, and having to string up these heavy cables (sure the conductor itself is light, but all that LN2 and insulation has got to weigh more then just the bare copper) is going to take alot more towers which for a long transmission line cost hundreds of millions, even billions for the really long lines out west.
If they bury the lines under concrete and other non-conductive materials, I wonder if we'll have another Project Seafarer-type situation on our hands. It might be helpful in regrowing trees quickly, though. Too bad there aren't any rain forests in the U.S. to replenish.
Well, it is not a niche market in e.g. Japan and other countries where most the people live in densitely populated areas where the capacity of existing copper lines is a serious problem (and building new towers not really an option in most cities).
I agree that it is not likely to replace very long power lines, but there is an existing big market for short-distance, high-current lines. Today they just use bundles of huge copper cables but they are also very expensive.
Second generation superconducting cables (the cable in the article is first generation, that technology was developed 10+ years ago and is already old) reached a bit of milestone last year, they can now be produced at a cost that is LOWER than copper cables with the same capacity (using RABiTS and other similar technologie).
Add to that the fact that they are not as thick as copper cables and therefore can be used to upgrade existing infrastructure and you can see why there is a lot of money being spent on this at the moment.
That said, power companies are very conservative. When they invest in new technology they need to know that the cables etc will work for several decades meaning they are sceptical about all new technolgies, it will take time for the technology to make a real impact. Much of the R&D is now focused on mechanical properties etc of these cables and people are trying to demonstrate that they are reliable, i.e not on the superconductor as such that is the issue, that is essentially "finished"; at least as a field of basic research (last year I attended a conference on applied superconductivity and by went to a "mechanical" session by misstake, had to listen to several boring talks about cable bending, stress-testing etc; not something I am very interested in since I work in device physics:frown
. 
Well liquid hydrogen needs a much lower temperature, so it would be harder to obtain. not to mention the fact that liquid hydrogen has a relatively low energy density, and the conversion between gas to liquid and back to gas would probably be rather efficient. if you wanted to transmit energy across long distances electric lines are a far more efficient energy carrier then liquid hydrogen.
PowerEngineer
Diamond Member
- Oct 22, 2001
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Because it's the losses in conductors that impose limits on how much power can be carried, superconductors would certainly increase what we could push down existing right-of-ways. There's been talk of applying superconductors to the power system for decades, but very little has actually been done. It seems that we need that breakthrough to (or at least towards) high temperature superconductors before we'll see much of it applied.
It could still be useful if you were running from a power plant to a city - electricity for the grid plus hydrogen, generated at the power plant for minimal transmission losses, for fuel cell or hydrogen vehicles, assuming they existed.
As HV transmission lines go this example is pretty mundane.
Current trends in long distance transmission are 750,000Volt+ DC lines. Advances in solid state switching have made AC transmission lines and the accompanying inductive losses old news. Voltage converion that use to be difficult before solid state switching is relatively simple. The extreme high voltages that are headed ever higher are reducing resistive losses. It looks to me like the super conductive lines will be relegated to urban settings.
Current trends in long distance transmission are 750,000Volt+ DC lines. Advances in solid state switching have made AC transmission lines and the accompanying inductive losses old news. Voltage converion that use to be difficult before solid state switching is relatively simple. The extreme high voltages that are headed ever higher are reducing resistive losses. It looks to me like the super conductive lines will be relegated to urban settings.
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