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Science Technology

Thermoelectric Generator With No Moving Parts 43

Posted by timothy from the iceland's-upside dept.
Savage-Rabbit writes "These guys have produced a working prototype of a thermoelectric generator. The thing uses extremely cold and hot liquids to achieve a heat transfer through a semiconducting material. This produces a voltage in the semiconductor who can produce up to 50-100 Watts which is actually enough for this thing to have practical uses. This generator could for example be useful in the chemical industry where many production processes generate a lot of excess heat that normally is simply lost. With a thermoelectric generator some of that lost energy could be recovered."
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Thermoelectric Generator With No Moving Parts More

Thermoelectric Generator With No Moving Parts

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  • Time to market? (Score:1, Interesting)

    by syukton ( 256348 )
    When do I get my full-body suit of this stuff, so that I may run my Pentium (tm) class laptop without plugging it into a wall every hour?
  • <PUN>Wow, they have finally broken the Second Law of Thermodynamics! The Second Law prohibits the transfer of useful work from a high entropy source (heat) into a low entropy source (an electric current). The Second Law implies that once energy becomes heat then it remains as heat which will dissipate to the surroundings causing an overall increase of entropy in the system. With this generator, we can finally decrease entropy in the world by turning heat into electricity! We can refigerate not only without expending energy, but we get some work for it! We can make black holes smaller by sucking the entropy from it. Finally we can make a perpetual motion machine!</PUN>

    • Re:Thermodynamics (Score:2, Informative)

      by Cs.Ender ( 615148 )
      Actually the flow of heat from one body to another as the two move twords thermal equilibrium can be used to do work. In the device, heat is moving from an area of high tempurature, to one with a lower temperature, not the other way around.
    • The Second Law prohibits the transfer of useful work from a high entropy source (heat) into a low entropy source (an electric current).

      So the steam turbines at the (nuclear or coal fired) power station aren't powering that computer you're posting from? I guess we all must live near hydroelectric stations then.
  • It's an Icelandic company, so they're developing in an environment where there's plentiful hot water (geothermal). I'm wondering if you could get enough hot water from rooftop water-heating panels. Not the thoroughly expensive photo-voltaic, the much simpler black pipes full of water sort. They're surprisingly efficient even in colder climes: my in-laws in the North of England get most of their hot water from a set. The combination might make this very useful for isolated buildings, even outside of volcanic hot zones.
    • It surprises me when I see them, but they even work out here in Montana. I am surprised that they aren't on more rooftops in warmer climates.
    • You're talking about heating water with sunlight, and then using a thermoelectric generator to turn that heat into energy.

      Wouldn't it be simpler and more efficient to install solar panels to directly turn the sunlight into energy?
    • Solar PV panels run up to about 14% efficiency, whereas Peltier junction devices run maybe 5%? If you're able to build 3 times as much area of collector for the same price, and you're willing to put up with the efficiency going up and down along with the rate of heat input (output voltage is proportional to the temperature difference, so you will have very low voltage and thus low power when the sun is low in the sky)... I suppose it might be worth it. I suspect (educated guesswork) that if you run the numbers you'll find that other approaches are more worthwhile.

  • Move along, nothing to see here... (Score:4, Informative)

    by BurritoJ ( 75275 ) on Monday October 28, 2002 @03:56PM (#4550166)
    This is just a Peltier device in reverse. Instead of using a forced flow of electrons to drive heat from a cold surface to a warmer one, it is using the flow of heat from a warm surface, through the Peltier element, to a colder surface to drive electrons, generating current.
    • This is just a Peltier device in reverse.
      What do you mean, "reverse"? The heat-into-voltage trick is exactly what people have been doing with thermocouples for over a century. It's grossly inefficient, but when you are just measuring temperature or only need a little juice and have a relatively large amount of heat to play with (say, like the pilot flame on a gas furnace), it's perfect.

      These guys have nothing new. If they really wanted something to crow about, they'd produce something like a small vapor turbine running on butane and try to get 12% efficiency out of the thing. If they could spin one of those on fluid bearings a la the people making microturbine generators, it should be just as reliable and quiet.

  • Thermocouples? (Score:5, Insightful)

    by Louis_Wu ( 137951 ) <chris.cantrall@gmail.com> on Monday October 28, 2002 @03:57PM (#4550177) Journal
    Wow, did that Icelander discover thermocouples? [inet.co.th] I can't believe the advances in science being made.

    Seriously, at my university, thermocouples are covered in a sophomore year mechanical engineering class [calpoly.edu] and lab [calpoly.edu].

    • Re:Thermocouples? (Score:2, Informative)

      by LWATCDR ( 28044 )
      I wondered about this also. I think the SNAP generators that they have been using on space craft for years also us a Thermocouple.
      Maybe these are cheaper/ better than average. Could they use them on the space stations to recover some energy from lost heat maybe?
      I remember that they have used things like this in Russia for years. They use a flame on one side and the russian winter on the other :)

    • Re:Thermocouples? (Score:2, Informative)

      by Tidan ( 541596 )
      Right on. It definitely works the same way as a thermocouple [omega.com], but it depends on how you use it.

      It's a thermocouple if you use it to measure a temperature difference.

      It's a Thermator if you use it to produce electrical power.

      While not a major breakthrough, it's good to find more ways to use waste heat and up the efficiency of a system.

    • It's VERY hard (is it even possible to get 100W!?) to get any real power out of thermocouples though.
      • It's VERY hard (is it even possible to get 100W!?) to get any real power out of thermocouples though.

        Very hard, but not impossible. Spacecraft using RTGs use thermocouples heated by isotopes to provide a few hundred watts of power.

  • Other uses (Score:3, Insightful)

    by taphu ( 549739 ) on Monday October 28, 2002 @04:00PM (#4550207) Homepage
    This generator could for example be useful in the chemical industry where many production processes generate a lot of excess heat that normally is simply lost.

    Not to mention all the heat lost in even more common things such automobile engines.
    • is the term you are looking for. Fuel is apparently still too cheap to make them worthwhile for things like cars; people would rather pay for the extra gas. AFAIK, even heavy trucks are still not using turbocompounding to squeeze the extra few percent out of their diesels. This is odd, because I read about Caterpillar designing a near-adiabatic diesel with turbocompounding around a decade ago, yett there's nothing on the market (but at least they're talking about it [osti.gov]).

  • Yankee Stadium (Score:3, Funny)

    by TheSHAD0W ( 258774 ) on Monday October 28, 2002 @04:27PM (#4550444) Homepage
    I figure, if they used cool water from the Hudson for the cold side, and warm, um, liquid from the urinals for the hot side, they could get the lighting for night games for free!

    Though they might want to lower the prices on soda and beer, just to keep things flowing.

  • Satalite power? (Score:2, Insightful)

    by charlie763 ( 529636 )
    Hopefully it could also be used in satalites. I always hear about the extreme temperature differences between the side that faces the sun and the other side.

    • Re:Satalite power? (Score:2, Informative)

      by n9hmg ( 548792 )
      I assume you mean satellite, but anyway...
      Yes, something like this is used in space all the time. RTG, SNAP, whatever you want to call it, heat from decaying radioactive fuel heats one end of a bank of thermocouples, and the heat bleeds off the other end, to generate electricity. Both manned [si.edu], and unmanned [216.239.37.100] have used them.
      Doesn't anybody remember when the logic-impaired Greenpeace types were whining about Galileo, with its RTG?
      Anyway, I just want to point out that, at least from the article, this sounds like another non-news thing. unless it's considered a big deal to use natural hot and cold water for the temperature gradient.

  • Perpetual Motion? (Score:3, Funny)

    by crisco ( 4669 ) on Monday October 28, 2002 @04:34PM (#4550529) Homepage
    Does this mean I can water cool my Athlon and keep the computer powered off the waste heat?

  • Efficiency: 1% (Score:5, Interesting)

    by jfengel ( 409917 ) on Monday October 28, 2002 @05:28PM (#4551042) Homepage Journal
    They claim:

    a generator that gets 3 litres per minute (0.8GPM) of 75C (167F) hot water, gives about 50 Watts when also supplied with the same flow of cold water used for cooling.

    They also claim to produce about a 20C drop in temperature. Theoretically that's 4,200 Watts (it takes a lot of energy to raise a liter of water 1 degree). So their efficiency is only 1%.

    I hope I've done the math right; high school chemistry was half a lifetime ago.

    • Re:Efficiency: 1% (Score:3, Informative)

      by siskbc ( 598067 )
      You got it right - they only use 50/4000 = about 1% efficient....for the heat they actually remove from the system

      Also realize that they only made use of a small portion of the temperature drop. Assuming they had a cold sink of infinite (relatively) mass, they should get a temperature drop of approx 65 C, assuming a typical icelandic 10 C temperature. So take that ratio as well and they made use of only about 0.4% of the maximum Carnot efficiency.

      However, carnot efficiency is capped as well - you can never get all the heat in the water - so then multiply by the carnot efficiency found from 75 C and 10C, which is 0.19. So now we're down to an absolute efficiency of about 0.06%. Not too good...

      To get the absolute efficiency the easy way, take 50g/s of water, and multiply by the temperature of the hot source, and also by the heat capacity of the material. Then divide the actual power by that.
  • The RTG's (radioisotope thermal generators) on the Voyager probes are spec'ed for 400 watts electrical from 1800 watts thermal. That's decent efficiency compared to these. And that was thermocouple based.
    • But the temperature of the cold reservoir there is much lower than that attainable on Earth, since the heat is being radiated off into space. The ideal efficiency is therefore, I would guess, something better than 50% (I'd have to know the temperature produced by the radiator system to get the exact ideal efficiency). So the Voyager RTGs would operate somewhere between ~20% and ~50% of the ideal efficiency, which really isn't that bad.

  • oh a wicked idea comes to mind (Score:3, Funny)

    by sckeener ( 137243 ) on Monday October 28, 2002 @06:08PM (#4551382)
    This generator could for example be useful in the chemical industry where many production processes generate a lot of excess heat that normally is simply lost.

    I have a request. I need something that works with body temp and here's what I'd do:
    Flip the power breakers off the night of my honey's favorite movie and tell her that the backup generator works off body heat. Oh course it'd be my luck that she'd tell me to start doing jumping jacks....
  • Amazing how many people instnatly think they can get free energy here. The breakthrough here is just profitability and efficiency, not new science.
  • Does anyone remember the Slashdot article on the CoolChip? It was basicly a really efficent peliter 70% or so. Well they have engineered it's brother, the powerchip. Give it heat xfer it gives you electricity. At a est 70% efficency.
    Powerchips [powerchips.gi]
  • Thermoelectric generators have already seen extensive service in remote areas where reliability is the main concern. One of the most common examples is for cathodic protection of oil and gas pipelines. Obviously in this type of application the fuel supply is a non-issue, which helps overcome the disadvantage of the TEG's low efficiency.

    Global Thermoelectric [globalte.com] has had a wide range of these systems available for quite some time.

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