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Science Technology

Real World High-Temperature Superconductor Engine 44

Posted by timothy from the now-for-the-hybrid-cars dept.
wes33 writes "An amazing technological achievement deploying high-temperature superconductors is reported in Space Daily. American Superconductor Corporation (nice scifi-ish name) has built a 5MW electric ship motor using high-temp. superconductor technology. The Queen Elizabeth's 44 MW engines weigh 400 tons each (and she has two); a single comparable HST motor (36.5 MW) will weigh 75 tons!"
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Real World High-Temperature Superconductor Engine More

Real World High-Temperature Superconductor Engine

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  • As far as i know, they use diesel generators to provide the power usually. Using HTS in the generator would/could provide a drastic improvement in the effciency, and would be a much more exciting development in my opinion.

    • Generators aren't critical... yet. (Score:5, Informative)

      by Engineer-Poet ( 795260 ) on Wednesday September 29, 2004 @02:55PM (#10387014) Homepage Journal
      The Navy doesn't like diesels because they're too noisy for vehicles which chase submarines. The alternative is a gas turbine, which spins fast enough that you can make an acceptably small and light alternator without going to extreme materials; only when you need to drive a low-speed propellor do you really need the high-current capabilities of superconductors.

      The technical explanation is that you can transfer a lot of power with a small, rapidly-varying magnetic field (like the itty-bitty toroid in your computer's power supply, running at 100 KHz instead of the 60 Hz power line frequency), but to transfer the same amount of power with a slowly-varying field needs a much bigger field, bigger currents and bigger losses. Superconductors get rid of the losses and can sustain bigger fields in a smaller package.

      • After reading the arcticle, the reason why these motors can achieve higher density is because the thermal dissapation issues are reduced when you don't have DC losses in your coil windings.

        You are right as far as lower freqencies needing more core material. But, I can't see how superconductors would change that equation at all. Even if the superconductor carries more current, the magnetic material has the same basic flux energy storage capacity. Ships tend to use higher frequencies anyway, such as 400Hz
        • the same basic flux [...] capacit[or]

          Yeah, I'll burn in hell... ;-)

        • I can't see how superconductors would change that equation at all.

          Power/volume is proportional to dB/dt. The lower the frequency, the higher B(peak) has to be to get the same dB/dt. Superconductors can maintain a higher B field under the conditions (heat dissipation, etc.) of large motors, so you can get more power out of them.

          Even if the superconductor carries more current, the magnetic material has the same basic flux energy storage capacity.

          Superconductors let you run with air cores; even iron isn

          • good points, and they help to demonstrate the trade-offs in transitioning to superconductors. The main issue is that superconductivity isn't a slam dunk, and it doesn't equal 100% efficiency. I think the article was just too rosy saying how revolutionary superconductors will be. The diminising returns of 1% efficiency improvment (claimed in the article) and smaller motors on a large ship may not justify the high maintainance and design costs of a superconducting system. I'd like to see how much plumbing
      • The Navy doesn't like diesels because they're too noisy for vehicles which chase submarines.

        But they're PISTONS. Imagine the ricing up you could do on this one [bath.ac.uk]. (yes, that's a 108,000 horsepower engine with cylinders you could fit a dozen or more people in)

        A set of four hundred 200w ground effect neons, a couple of (dozen) turbos and a blow off valve that can create more PSHHHHHHHH than your average small jet... and she'd be SLIK.

        or something
        • Yes, but can you imagine putting a piston through the head because of overspeed... at 120 RPM? (I know you're kidding, but I want to make a point.)

          That engine has a top speed of 102 RPM because it's direct drive. Direct drive eliminates the need for motor-generator sets and all the bulk, weight and cost people have been talking about above, but it also cuts the power output and increases the required size of the engine.

          Other marine diesels seem to be designed to run at 600-1000 RPM. An engine running at 6

  • disappointing article... (Score:4, Insightful)

    by nusratt ( 751548 ) on Wednesday September 29, 2004 @02:06PM (#10386453) Journal
    ...says virtually nothing about the actual HTS technology, which seems to be the only really novel aspect of this equipment.

  • More Power? (Score:2, Interesting)

    by the darn ( 624240 )
    Since they've made one that's comperable in power but much smaller in size, would it make sense to make one comparable in size and of much greater power as a replacement for use in existing vessels? Or are there other limiting factors in the amount of power that is useable in such circumstances?

    • Re:More Power? (Score:2, Informative)

      by tmacc ( 817603 ) *
      For retrofitting, you wouldn't want to put an engine of much greater power in there, it would destroy the other parts. It would be like putting an 800 hp engine in a car designed for an 180hp one.
      • A neighbour of mine had a Chevette 84 (originally 1.4 gasoline 70cv) retrofitted with a turbo 4.2 GM engine with 350cv or so. Obviously he changed a lot of other stuff as well, like brakes, transmission, suspension, etc, but the point is that the engine fit under the hood (with some effort -- he had to make a larger air intake in the front and he also had to put the battery and some other stuff in the trunk), so he put it there. And it worked like a charm.

    • Re:More Power? (Score:3, Interesting)

      by Timber_Z ( 777048 )
      Thats note the point. The point is that is FAR more effient then current technologies. The exact implemention is trival. Every so often technology makes a huge jump in performance that has a major impact on an industray. (Like moving from Hand Saws to Chain Saws for lumber: for example) This looks like it might be one of those times.

    • Re:More Power? (Score:5, Insightful)

      by Cecil ( 37810 ) on Wednesday September 29, 2004 @02:37PM (#10386809) Homepage
      Or are there other limiting factors in the amount of power that is useable in such circumstances?

      For a boat? Sure, cavitation. Propeller blades can only spin so fast (that is, push a certain amount of fluid) before they begin to create destructive turbulence in the fluid that cripples their pushing power. The same basic problem exists in aviation, which is why propeller-engine planes can only go so fast regardless of how big and numerous the engines and blades are. Jet engines, rockets, or some other form of propulsion are needed to go any faster.
      • Offtopic stop here:Their?, There? As in over there tracks? Dude I don't get it.

        Do you mean Their which is the same word whether it's refering to the popups or someone else who would be forced to look at popups
        • He's pointing out the incredible lack of language skills evident in MSNs' marketing department.

          Two mych dependentf onne "fpell checker"
          • Good I thought he was pluging some form of MSN browser plugin, which I imagine would require using I.E.
          • You are exactly correct. I think it's ludicrous that large companies can make blatant blunders like improper use of 'there' and 'their' in promotional materials intended for general consumption. If you want to impress me with your marketing, that's the #1 way not to do it.

            Although I think I am getting tired of that sig. Perhaps it's time to change it.

            (For the people viewing this thread later on, the sig in question refers to an ad on Hotmail which reads: "Help stop spam and pop-ups in there tracks with MS

    • No, more efficiency. (Score:5, Insightful)

      by the_twisted_pair ( 741815 ) on Wednesday September 29, 2004 @02:46PM (#10386920)
      It's all about efficiency, and therefore running cost. Optimum cruising speed is set by considerations of wave drag for a given hull - there's a sharp curve, whereby faster cruises become *incredibly* inefficient. Big marine diesels providing this motive effort are far and away the most efficient prime movers on the planet, because economies of scale and the singular nature of the task lends itself very well to such optimisation - which the owners take advantage of.

      The bottom line is that every single %age point gained represents a huge saving to the owners in fuel cost. If it can be done with a lighter/more efficient propulsion package, so much the better - that's extra cargo that's free to carry, but the prime incentive is fuel cost - you may not realise we're talking *thousands* of tons for oil bunkers on big ships...

      I'm not at all surprised that marine propulsion is the first major application of high-temp superconductors in this regard.

    • Yes, hull shape (Score:3, Interesting)

      by leonbrooks ( 8043 )

      are there other limiting factors in the amount of power that is useable in such circumstances?

      At a certain velocity dependent upon the shape, the hull changes from slicing through the water more towards trying to push against it, once you cross this knee, you need to add bucketloads of power for a very small improvement (basically, until you get your aquatic beastie to plane).

      Modulo propellor cavitation, hull collapse and other stuff which becomes dominant at those power levels, it would be quite a joy t

      • I've always wanted to see an oil-tanker sized ekranoplan type vehicle. The largest of the russian prototypes carried 100 tons, I wonder if it would scale up to 10,000 :)

  • what temp? (Score:4, Interesting)

    by klossner ( 733867 ) on Wednesday September 29, 2004 @04:09PM (#10387967)
    The article is silent on exactly which temperature this high-temperature superconductor requires. Are we still at liquid-nitrogen temperatures or have we gone higher?

    • Re:what temp? (Score:3, Informative)

      by SurG ( 817697 )
      The link to their website [amsuper.com], mentioned earlier, has some really nice technical papers. For one type of the wire they use some complicated compound with Tc =110 K. Didn't find Tc for the second type of wire (Y123). I'm pretty sure, however, that even if Tc is higher than 77 K, they still run it on 77 K, since other parameters like Ic should be better than around Tc. And nitrogent is pretty much standart cryoagent anyway. Their critical current for those wires looks pretty impressive (> 100 A

    • high-temperature superconductor requires. Are we still at liquid-nitrogen temperatures

      We still are - high temperature refers to a long way above absolute zero, since superconductivity was originally seen close to that temperature. Liquid nitrogen is relatively easy to make, easy to transport and in most places is cheaper per litre than milk. Having an entire power grid cooled by the stuff would be a mammoth infrastructure task, but with an engine you just have a big tank of the stuff. On a large ship it

      • Re:what temp? (Score:3, Informative)

        by merlin_jim ( 302773 )
        Why does everyone say with superconducting wire in the power grid that the cooling is the hard task?

        That's not it, it's raw current carrying capability. Superconductors break down at high currents. Cooling a superconducting wire isn't as hard as you might think.

        Superconductors conduct heat as well as electricity. The Newtonian description of the heat of a superconductor is the net average of all the temperature deltas it's exposed to integrated over the area of exposure. A superconducting wire is (in
        • At both ends, have a heatsink of superconductor material embedded in liquid nitrogen. As long as any liquid nitrogen remains, the entire wire will be at the temperature of the liquid nitrogen. The only reason you need a heatsink is to spread out the area of contact so you don't boil the liquid nitrogen so fast that large air bubbles form on the surface of the heatsink.

          Just cooling the ends isn't likely to work well, but cooling is still not a fatal problem. In a lot of applications, even conventional cop
          • Just cooling the ends isn't likely to work well, but cooling is still not a fatal problem.

            Can you please elaborate? What problems do you see with this?
            • Conducted heat is proportional to the [(area of the conduction path)/(length of path)]*(Temp gradient along that path)

              For a long skinny wire you have heat leaking in through a large area (diameter*length) conduction path that's very short (a few cm from any outer insulation to the inner wire) and with a very large temperature gradient (300K to 77K along that short path). To conduct that heat out you have a small area (a few cm square), a very long length (hundreds of meters or even km) and a very small te
        • It's not immediately clear to me why the propagation speed of heat in a wire (dist per deltadegree per time?) should go from very low in a non-supeconductor to speed of light when the same material is superconducting... after all, the electrical propagation speed isn't affected, is it?

          I'd much appreciate an intuitive description of why this is the case.

          thx
          • Heat is random kinetic energy. This energy can be transferred by electrons in a conductor, termed electric convective heat transfer, and this is why most good conductors of electricity are also good conductors of heat.

            I tried to google for references; some indicated that this was the case, while others specifically counter-indicated it! I don't know what to believe any more... one source specifically indicated that Cooper pairs interact poorly with their host material and this is the reason for poor heat

        • That's not it, it's raw current carrying capability

          Not really a problem if you have enough of them and a big enough gap between them to handle magnetic feild limits. I remember reading out designs that got around this more than ten years ago.

          Make the wires thin

          One problem with the superconducting materials is you can't work them, so you can't extrude them as wires or like glass fibre, and you certainly can't melt the materials we have and expect them to solidify as anything that superconducts. The compon

          • so you can't extrude them as wires or like glass fibre

            They mix them with silver to make them more ductile. They can be made to be bendable comparable to other large cables, but not bendable like little bitty computer cables. Some of the low temp superconducting materials are also very brittle (Nb3Sn) but people have managed to use them very effectively for high field magnets. At least some HTSC wires are made in much the same way as low temp superconducting wires, where they draw it into a long wire, cu
        • Superconductors conduct heat as well as electricity. The Newtonian description of the heat of a superconductor is the net average of all the temperature deltas it's exposed to integrated over the area of exposure. A superconducting wire is (in a non-relative universe) always the exact same temperature throughout.

          If this is true (as noted in a child, sources seem to conflict), then there must be a critical figured for heat conduction too, else you could move enormous amounts of heat energy as easily as ele
          • Wow. Great insight there. I had never considered that angle; you must be right.

            As to whether or not its true, on further research I found that some sources agree, some disagree, but noone seems to have any hard figures posted online either way. I'm considering ordering a labtech DSP and checking it out for myself.
    • According to that site http://www.amsuper.com/products/htsWire/ [amsuper.com] it is likely to be under 100K, and most info being given at 77K, sounds like liquid nitrogen cooling.

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