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Power Science Technology

Ohio Researchers Advance Heat Reclamation Technologies 124

Downchuck writes "Researchers at Ohio State University claim to have synthesized a new material capable of delivering electricity directly from heat, at an efficiency far better than existing thermoelectric materials. Scott at ArsTechnica has an interesting take: 'Merge this with the new MIT solar dish and you're in business!'"
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Ohio Researchers Advance Heat Reclamation Technologies

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  • But I like this [] better.

    • Who about this:

    • That's neat and all, but the carnot efficiency of your wind generator is very low, so you have to use *much* greater area than with a traditional solar-thermal generator.

  • Finally! (Score:5, Funny)

    by Anonymous Coward on Sunday July 27, 2008 @05:39PM (#24361299)

    Finally, we have a truly renewable source of energy - we can just harness all the hot air coming from our politicians.

  • Technical point (Score:5, Insightful)

    by Bruce Perens ( 3872 ) * <> on Sunday July 27, 2008 @05:41PM (#24361323) Homepage Journal
    It's not possible to make electricity directly from heat. It is possible to make it from a difference in heat between two points.
    • by ettlz ( 639203 ) on Sunday July 27, 2008 @05:47PM (#24361369) Journal
      Yes, on this site we obey the Laws of Thermodynamics!
      • by Anonymous Coward on Sunday July 27, 2008 @06:21PM (#24361581)

        The other campaign may call it pandering, but I think the American people deserve a temporary holiday from the Laws of Thermodynamics.

        • I also propose a 90-day gravity holiday, during which time I will get rich selling flying cars.

        • The other campaign may call it pandering, but I think the American people deserve a temporary holiday from the Laws of Thermodynamics.

          Meanwhile, in Cobb County, those would be referred to as the Theories of Thermodynamics, after all energy is^H^H could be inteligently designed...

        • Have you been smoking moon rocks? Dont you know thats loco?

          Somebody think of the children!
        • Actually, there are temporary vacations from Thermodynamics happening all the time at the nano-scale level. The "laws" of thermodynamics are "laws" of averages over astronomical (standard units being 6.023x10^23 molecules) numbers. There is no law that says your room temperature glass of water can't suddenly begin to boil while sporting ice cubes. It is just astronomically improbable (but not improbable enough to power a starship). For that matter, resurrection from the dead is not impossible - just ast

    • Re:Technical point (Score:5, Informative)

      by cnettel ( 836611 ) on Sunday July 27, 2008 @05:49PM (#24361389)
      You make electricity directly from heat. You can't make electricity directly from temperature (or stored heat) though.
    • Re:Technical point (Score:5, Informative)

      by Anonymous Coward on Sunday July 27, 2008 @05:51PM (#24361403)

      It's not possible to make electricity directly from heat. It is possible to make it from a difference in heat between two points

      heat != temperature

      But you are right that you have to have a cold reservoir to get any work from the system. But heat in thermodynamics is not the same as temperature, and it generally denotes the amount of transfered thermal energy between two systems of differing temperature.

      I'm assuming that the cold reservoir is the cooler temperature air surrounding the device.

    • Re: (Score:2, Informative)

      by cool_arrow ( 881921 )
      Yes that is true and I believe that the most efficient thermoelectric devices are somewhere in the range of about 5% efficiency in practical applications.
      • Re: (Score:3, Insightful)

        by Bruce Perens ( 3872 ) *
        Oops, I'm getting whipped for "heat in a thermodynamic sense is not the same thing as temperature". But yes, the point here is that they've invented better thermocouple wire and thus possibly an improvement in thermoelectric generation and maybe the Peltier effect. Doubling the efficiency of those things would not necessarily make them competitive with other processes for heating and cooling.
        • Re:Technical point (Score:5, Informative)

          by Doc Ruby ( 173196 ) on Sunday July 27, 2008 @06:53PM (#24361837) Homepage Journal

          But quadrupling them would. The old max zT these researchers were improving was about 0.87. They've now got it to about 1.5. And are targeting about 3.0 in their current research.

          Freon refrigerators have a zT of about 3.0. Which makes these new materials look directly competitive with them for cooling when they reach that efficiency. Since zT 1 materials are about 10% efficient, zT 3 will be able to reclaim about 30% of waste heat. That would be about 20 points of the ~60% of gasoline energy wasted as heat in car engines. Since car engines are about 20% efficient now, that would mean doubling their fuel efficiency.

          If these materials can be made, deployed, and recycled with close to (or less than) the energy inputs required now to make the car radiators/manifolds/exhaust systems they'd probably mostly replace, the benefits would be revolutionary.

          • ^Even if improved thermoelectrics can't directly compete in a refrigerator-type application, any improvement in their efficiency will be useful in other applications (computer cooling, portable thermoelectric cooler/wamers, etc.)
          • Re:Technical point (Score:5, Interesting)

            by Doc Ruby ( 173196 ) on Sunday July 27, 2008 @10:40PM (#24363563) Homepage Journal

            The Technology Review [] article about the tech is more specific about the material's heat/electricity conversion efficiency. Evidently the current zT:0.87 material is about 6% efficient; the zT:1.5 material already achieved therefore is about 10% (about 10.3448276%) efficient. A zT:3.0 device is about 21% (about 20.6896552%) efficient.

            10% of the 60% of gasoline's energy content wasted as heat is 6% of the gasoline's energy. If the car got the average 20% fuel efficiency, that extra 6 points would be 30% more than the original 20%. A zT:3.0/21% would be 12.6 points extra, or 63% more than 20% to 32.6%.

            A 30MPG car today would get 39MPG tomorrow with the current version material. It would get 48.9MPG with the forecast zT:3 material.

            What I'm really interested in seeing is how embedding the higher zT materials inside fuelcells boost their efficiency. Because fuelcells aren't heat engines, they're not limited to the Carnot Cycle's 40% max efficiency. They already get 50% efficiency or greater at "native" voltages (like 1.48V), where their max theoretical efficiency is 83%. But still, much of their 17%+ inefficiency is generating heat. So they can be even more efficient with heat reclamation, perhaps in practice actually approaching that 83% efficiency.

          • Re: (Score:3, Informative)

            by Lisandro ( 799651 )
            RTGs (radioisotope thermoelectric generators) would benefit greatly from this aswell. They tend to have long life spans (in the order of the half-life of the radioactive material used), but radiation decay and thermocouple wear reduce their power output much before that.
          • Well, first, when we get these materials to 30%, not their "we'll be a 3% soon" level, you let me know.

            Until then capturing 3% of 60%, but adding weight, complexity, and cost to the vehicle, I doubt will have any real benefit. Even at 10%, we're still looking at better improvement simply by switching to electric drive with gas backups.

            If we follow the ideas presented by, then we don't need to worry about it anyway. If we replace oil with man made liquid fuel, produced using free energy

            • Current zT:0.87 can get about 6% efficiency; these new materials at zT:1.5 get about 10%; their forecast zT:3 materials will get about 21%, in engines like in our cars. I don't know where you're getting that 3% efficient heat recovery figure from.

              Every mechanical process could benefit from recovering significant amounts of heat. Most heat engines, especially gasoline/diesel types, include extra machinery for exhausting heat which could be replaced with probably simpler devices that are like "catalytic conve

              • The exhaust process is a function of vapor expansion,not so much heat dissipation. If we impede that process, we reduce the efficiency of the engine itself. Can we collect enough heat as it flies through the exhaust pipes to recoup more than the combined engine impact, additional weight, and cost?

                If our fuels come from green sources, and if CO2 emission of the engine is a non-issue, than only distance per gallon is of concern. If we use WindFuels (, at least until something better come

                • Even if we extract 20% of the energy from hot exhaust, it'll still have 80%, which will make it work about how it works now. But the radiator and manifold won't have to work as hard, be made as durable, consume as much energy in manufacture, deployment and recycling.

                  • Again, with their current hopes of 10%, 20 sounds like quite a bit off from now in time. Also, can that 20% be maintained without adding back pressure to the engine, reducing it's efficiency, and also, what will this system add in vehicle costs, space requirements, maintenance charges, complexity, and weight?

                    I think the system is great for large scale applications, but my understanding of the technology is that it 1) does not translate well to extremely small scale (the inside surface of an exhaust system)

                    • The scientists say they'll have a product on the market in something like 3-4 years. Which, since they're working under the Ohio State patent office, means they're probably close to producing the product itself, and are just talking about patent and licensing time. The zT:1.5 material isn't a very competitive product, at 10% efficiency, to enter the very conservative automobile market with its new technology and approach. I expect that they expect to market the zT:3 material, with its 21% efficiency in the

                    • Even at $10/gallon (which we'll have Windfuels competing with at $3.50 a gallon) at 12,000 miles per year, and 150MPG average use, we're talking $160 per year savings at 20% reclamation. Over a 10 year vehicle lifespan, assuming maintenance or material replacement is nominal, you'd still need to have this total system cost less than $1600, with no impact on engine efficiency at 20% re-use. I assume there will be some engine impact. and although the material may make 20%, that assumes constant contact wi

                    • 20% reclamation of the 60% energy wasted as heat is 12% extra efficiency. If that 12% is worth only $80, that means that 100% of annual gasoline expenses is only $670. At $4 a gallon (which is 2008's average, not 2013's), that's 166.7 gallons, which at 35MPG is 5833 miles. 500 miles a month.

                      Something's wrong with your math. Average annual mileage [] is at least double that.

                      Besides, there are other costs for the lower mileage. More frequent fillup stops/trips. Environmental damage.

                      People will pay more than $500

      • Yes but if we were driving our cars around on Pluto, even a tiny temperature gradient could be made to do far more useful work than the same difference in temperature on Earth. This planet is a little too warm for these gizmos and so you see signs of desperation such as thallium.

        We need to build a giant ring in space that orbits the sun and keeps the Earth in perpetual shadow. That would allow a wider selection of designs for engineers trying to use exhaust heat to turn wheels. Of course, that's only if you

    • Please mod this guy down!

      Would you mind explaining us what the "difference in heat between two points" is? Heck, what is the heat of a point? (hint: it's undefined)
      Make yourself a treat : buy yourself a good thermodynamics book and come back when you're finished.

      Thank you.

  • by 4D6963 ( 933028 ) on Sunday July 27, 2008 @05:45PM (#24361351)
    Could it be used to get more power out of a nuclear power plant?
  • Peltier elements are used to rapidly cool small surfaces (such as PCR racks, etc), and they use electricity and some trick of semiconductors to do it ( So this is a reverse peltier effect then? cool...
    • by cnettel ( 836611 ) on Sunday July 27, 2008 @05:52PM (#24361407)
      Any Peltier element can give you power as well. The point is that even the theoretically optimal difference is totally lousy if your heat difference is somewhere like the one between water freezing and water boiling. You need a colder cold sink, or a much hotter heat source, to get some serious efficiency. RTGs tend to be quite hot in the hot end.

      This allows better RTGs, but they would only be marginally efficient for, say, reclaiming computer case waste heat. This is especially so as you can't put them on the CPU directly, where the differential is great, because they are insulating as well. You will need to put it at the radiating end, over a large surface.

    • Use power to shift heat or generate power from heat flow.
    • You can run peltier elements backwards.

      The problem is that efficiency is utterly lousy to begin with, and then degrades, so it is only used in very niche applications. If the new material improves even just the lifetime issue, it expands usefulness quite dramatically.

  • Hot technology (Score:3, Interesting)

    by gmuslera ( 3436 ) on Sunday July 27, 2008 @05:50PM (#24361399) Homepage Journal
    That material reach its peak at 950F (~500C). Not sure if MIT approach will worth combining with this as maybe the area needed could make electricity by other means.

    But there are a lot of areas where heat is produced, and some of this could be used to get extra electricity.

    Maybe the most important point, at what cost? how rare/expensive is that new material? If is very, maybe the main use would be not for our normal lifes, but maybe for i.e. space probes.
    • by jonadab ( 583620 )

      > That material reach its peak at 950F (~500C).

      I think my attic gets nearly that hot in the summertime...

    • Re: (Score:3, Informative)

      by sokoban ( 142301 )

      Maybe the most important point, at what cost? how rare/expensive is that new material? If is very, maybe the main use would be not for our normal lifes, but maybe for i.e. space probes.

      Lead is very cheap, Tellurium is about 20 some odd dollars per pound, but Thallium is damn expensive. In the late 90's Thallium was running about $600 per pound. That said, I'm not sure how much Thallium will be needed for this application.

      • Re:Hot technology (Score:4, Insightful)

        by im_thatoneguy ( 819432 ) on Monday July 28, 2008 @02:31AM (#24364797)
        Well we are using Platinum in extremely warm car parts as it is. So placing rare earth metals in our exhaust system isn't a far out idea in the automotive industry. ;)
        • by sokoban ( 142301 )

          Well we are using Platinum in extremely warm car parts as it is. So placing rare earth metals in our exhaust system isn't a far out idea in the automotive industry. ;)

          Right, but there is roughly 1-3 grams of catalyst in a catalytic converter in a car. The article doesn't say how much Thallium is needed in this application.

    • Maybe the most important point, at what cost? how rare/expensive is that new material? If is very, maybe the main use would be not for our normal lifes, but maybe for i.e. space probes.

      They already use materials like this in space probes - you put a hot radioactive isotope at the end of one of those long rods and thermoelectric generators through the rod - they're ridiculously inefficient right now, but there are no moving parts they're less likely to break down, which is more important on long, unmanned space missions. I'm a materials engineering major and one of the things we were told in our intro class was that if anyone ever figures out a way to make this type of material more effic

  • Geothermal plug in (Score:3, Interesting)

    by SubComdTaco ( 1199449 ) on Sunday July 27, 2008 @05:50PM (#24361401)
    From the article: "the material is most effective between 450 and 950 Fahrenheit" So simply plug this into a geothermal source, instant energy solution until Earth's core freezes.
    • From the article: "the material is most effective between 450 and 950 Fahrenheit" So simply plug this into a geothermal source, instant energy solution until Earth's core freezes.

      How about those floating colonies on venus?

  • This research was funded by the BSST Corporation; the State of Ohio Department of Development's Center for Photovoltaic Innovation and Commercialization at Ohio State University; the Beckman Institute; the Swedish Bengt Lundqvist Minne Foundation; and NASA's Jet Propulsion Laboratory.

    Heremans' team is continuing to work on this patent-pending technology.

  • by Doc Ruby ( 173196 ) on Sunday July 27, 2008 @06:02PM (#24361473) Homepage Journal

    The article at the Green Car Congress site titled New Approach to Developing Thermoelectric Materials Doubles Efficiency" [] has a lot more scientific details than that article linked from the summary, especially on the actual formula that determines "zT", which is the thermoelectric conversion efficiency coefficient:

    The dimensionless zT for thermoelectric materials is calculated by the formula zT= T*(S2)/), where S is the thermoelectric power or Seebeck coefficient of the TE material, and are the electrical and thermal conductivities, respectively, and T is the absolute temperature.

    And also detailed nanomaterials engineering analysis of the quantum structure of the quantum chemistry's thermoelectric effects.

  • No mention of actual cost as far as I can tell. It's twice as efficient but does it cost 100 times more or twice as much? The former probably makes it far less useful, the latter would be great.
    • Re: (Score:1, Funny)

      by Anonymous Coward

      does it cost 100 times more or twice as much? The former probably makes it far less useful, the latter would be great.

      A very good point! But let me make sure I understand it. You're saying that it would be better if it cost less? Man that's some good thinking. How do you do it?

    • Cost compared to what?

      Gasoline and other petrofuel prices are going nowhere but up, up, up, until there isn't enough to use for fuel anymore (oil and natural gas, anyway). And the actual costs of pumping all that CO2 into the Greenhouse are hard to calculate: how much does Greenland melting the seas 20 feet higher cost?

  • by Horar ( 521864 ) <slashdot.asmith@id@au> on Sunday July 27, 2008 @06:06PM (#24361503) Homepage

    ... contain a link to a possibly more useful article with some more comprehensible numbers: []

    e.g. The device could increase fuel efficiency of vehicles by approximately 10 percent.

  • Merge this with the new MIT solar dish and you're in business!'

    Ah cool, now we know:

    1. xyz
    2. ???^H^H^H Invent thermoelectric material
    3. Profit!
  • by Doc Ruby ( 173196 ) on Sunday July 27, 2008 @06:19PM (#24361571) Homepage Journal

    Even though that article linked from the summary says that typical engines in cars get about 25% of the gasoline's energy content into car motion, it's actually about 20% []. That's a lot of wasted energy: about 4:1 waste:use.

    But lots of combined cycle plants [] (like CCGT gas turbines) reclaim a lot of their waste heat into more power. Taking a maximum mechanical power extraction of 60% of the gas' energy up to 85% by heating steam, which is an additional 25% of the original mechanical power.

    CCGT reclamation tech is probably not practical for vehicles, so this new material is a welcome advance. Especially if the researchers get the zT from its new 1.5 high to its predicted 3.0 or so. But in fact DARPA has funded Trinh Vo at Lawrence Livermore National Labs to grow nanowires that already have a zT at 3 [].

    More of that kind of material research is very welcome, because at zT 3, these materials can replace freon refrigerators with the same electrical efficiency. Since freon refrigerators require lots of energy to build, and then to recycle, replacing them with a simple material that can scale to any size (including very small, as in microelectronics), means a vast sector of modern industry, including transportation, could switch. If making the material is less energy intensive, and less reliant on a limited critical resource than the freon refrigerators or the CCGT reclamation systems, global energy efficiency could take a giant leap.

    A leap that could be just around the corner, in Ohio.

    • >at zT 3, these materials can replace freon refrigerators.

      Uh, how? The Freon cycle can give EERs of 15.
      An average Peltier device has an EER of under 0.4.

      The numbers don't seem to work out.

    • It would also likely have dramatic health & nutrition impacts in developing countries, as refrigeration becomes economically accessible to people who would not previously have been able to afford it.

      That might partially offset the energy savings, but since it would have direct benefits in reducing food wastage, it's still a very good thing.

      • by MobyDisk ( 75490 )

        They aren't saying that this material would make a more efficient refrigerator, only that it would be a simpler/cheaper one. I am guessing that places that don't have refrigeration are that way due to a lack of a power source. I'm not sure this will help.

      • This is still way too expensive for developing countries - even though the refrigerator itself may cost less to build and service, the energy costs don't really improve. With few or overstressed power systems, this isn't going to help.

        What can help is "Pot-in-pot" refrigerators []. Two nesting unglazed ceramic pots, separated by wet sand and covered with a wet towel, will keep the interior cold enough thru evaporative cooling to keep vegetables fresh for up to two weeks.

  • Unobtanium anyone?

  • What's this power efficiency rating? How much is 1.5 in God's honest Watts per Kelvin, or a simple percentage of power in/power out?
  • A while back there was an article on /. about a "quantum afterburner" : a device that could directly extract energy from a heat source, say, car exhaust, in the form of a laser beam.

    Here's a link to the cached Nature article : []

  • Just attach a generator to the lower jaws to my husband and his mother. The energy they produce by moaning about the heat should cool the whole of Cologne for the summer.

  • This advance's benefits are all described in terms of an increased zT [] now up to 1.5, predicted to go up to 3 or so in the really perfected version of the material. But what does "zT" mean in actual efficiency?

    In real terms, let's say that a car engine today consumes about 300KW total contained in its gasoline flow, converting about 20% of that into 60KW for forward motion, and about 60% of that into about 180KW of heat (out the exhaust, and heating the engine/radiator, car and road). If the zT 1.5 material

    • Re: (Score:3, Interesting)

      z is related to the Seebeck coeff (which tells you how much voltage a given delta-temp gives you in a material), the resistivity and thermal conductivity. It is multiplied by T (the average temp at which the performance is measured) to give a non-dimensional number.

      zT doesn't tell you the efficiency because that would depend on the delta T (next para), but it is roughly proportional to it for given operating conditions. zT = 1 materials have efficiency maybe around 5% under best conditions, for zt = 3 yo
  • Remember a few days ago there was an article about paint being able to help absorb sunlight for use on solar panels, well combining the two could actually work with absorbing light and heat energy from the sun.
  • I wonder what this kind of technology, once sufficiently advanced enough to absorb the high levels of heat, could do to change nuclear reactor designs.
  • If this stuff can efficiently convert heat to electricity with very little energy input to manufacture it (compared to, say, steam engines), and can withstand high temperatures without being destroyed, what would it do to geothermal electric production?

    Would it not only increase the efficiency of the plants, but perhaps also make accessible lots of geothermal that is expensive to reach with today's bulky mechanical probes? Could we just drill to hot depths, then snake cables down it, and "plug into the grou

    • I think there is still a loong way to go to compete with modern land-based thermal plants. Even modern ships stretch their diesel impressively far.

      But for applications where you can't lug around industrial-scale heavy machinery, all improvements in heat reclamation are welcome, even though it's all in a different ballpark for the foreseeable future.

      • I think increasing the efficiency of thermoelectric materials will be welcome in all thermal plants, whether stationary on land or otherwise. There is no need for competition in these technologies, they're complementary. I'd love to see geothermal efficiency jump by 20%.

        But there's also probably lots of places that can't support a full geothermal plant. But which could support some dinky infrastructure about as heavy as an old-West windmill. If it were made of this stuff, that could mean quite a lot of powe

        • By thermal I meant all electric plants powered by heat (coal, oil, gas, nuclear, geothermal, solar-thermal). They don't use thermoelectric conversion because top-end mechanical conversion is much more efficient, and probably still will be even with this new step in thermoelectric converters.
          Waste heat is better used for heating, and in any case don't delver the sort of temperature gradient you need for efficient thermoelectric.

          I agree that small-scale stuff is probably nearer in time as a viable applicatio

  • by D4C5CE ( 578304 ) on Sunday July 27, 2008 @07:22PM (#24362057)

    thallium-doped lead telluride

    An achievement made up of toxic elements, the first being rat poison, the last being the rarest there is. Chances are this won't be cheap to make nor to dispose of, and I wonder what hazards it would pose to the environment if released (vehicles do crash or get abandoned from time to time).

    • by ceoyoyo ( 59147 )

      Not even close to the rarest there is. Tellurium is a little more common than gold or platinum. We already use platinum in catalytic converters. As you say, thallium is something that can be found in the average garage or basement already.

  • Sweet. Without actually researching further than a couple links, it looks as if this doo-hickey thing-a-ma-bob will be able to replace alternators (or in some few cases, generators) on vehicles. Sweet. It wonÂt wear out, since there are no moving parts. ItÂll last the lifetime of most vehicles, reducing upkeep expenses, it should weigh considerably less than an alternator, which will help fuel efficiency. I like it. Heck, you canÂt HELP liking it!! Hope it makes itÂs way to market
  • by WindBourne ( 631190 ) on Sunday July 27, 2008 @11:18PM (#24363789) Journal
    Johnson Thermoelectric Energy Conversion System []? Seriously, this one is being developed to operate at lower temps. I wonder if this new one will work better or not? But it sure would be useful to add one (or both) of these to say power plants to absorb some of the heat and continue generating more electricity.
  • Where's my thermoelectric flying car, goddam it!
  • Most boat owners could really do with a cheap generator that produces not more than around 25-50 watts (which will drive your central heating system in colder climates and your refrigerator in hot ones - you don't really want a big Diesel running for hours a day and big batteries for when it is not running.)

    A few years ago I investigated thermoelectric generators and contacted the suppliers. The unit is basically a thermoelectric generator, air-cooled, with a propane heater providing the hot side. Which at

  • "The invention, thallium-doped lead telluride, is twice as efficient as the second most efficient material used in thermoelectric power." Erm, how much more efficient is it than the FIRST most efficient material?
    • Even after reading the article, you can't think if *anything* that might be more efficient than the second most efficient material?

  • Meny have pointed out that such a device is useless w/o a temperature gradient. However, when such a gradient exists, there is a solution that is much more potent, commercially available and suitable for use in most environments that I can think of right now. I'm of course talking about the Stirling engine!
    During extremely favourable conditions such a device, combined with a generator, can turn as much as 30% of the energy in the gradient into electrical power!!! That, my friends, is a lot!
    A more polite and

Unix soit qui mal y pense [Unix to him who evil thinks?]