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  1.  (5748.1)
    I've been researching this kind of thing for an associate of mine, and the way it looks to me is that this is a highly underfunded area of science, as well as populated with the assortment of nut cases you find with this kind of thing.

    Thermoelectricity is the name of the game, but the right people aren't playing. Well, this guy seems pretty on the ball, but getting electricity from sound seems a bit... noisy of an application.

    But they way it looks is its either this which is still in the concepts phase, bi metallic strips of bismuth or lead telluride which has low efficiency, or nano materials with also low efficiency.

    Am I missing anything? Will heat always just be a big waste of energy, or will it someday be usefully without resorting to what is basically a big ass steam engine?
      CommentAuthorJon Wake
    • CommentTimeMay 4th 2009
    I'ts likely to be inefficient for quite a while--heat loss being the biggest measure of entropy in a system. Now, if you could develop a nano machine to transfer the kinetic energy of heat on the molecular level to electricity, stacked with insulators to regulate the flow of heat, then you'd lose less heat to the atmosphere and increase efficiency.

    On the other hand, heat is cheap and everywhere.
  2.  (5748.3)
    I've posted a couple of times here on this.

    Firstly the nano-structured materials capture a lot more of the energy than the older versions - 6-8% versus around 2 from memory.

    Secondly, there are a bunch of designs for low temperature turbines using working fluids other than water. Some of these can generate energy from waster heat sources below 80 degrees Celsius.

    I posted an article here about one of those recently. I'll try to link to it later today.
    • CommentAuthorKosmopolit
    • CommentTimeNov 18th 2009
    Turning heat to electricity... efficiently

    Hagelstein says that with present systems it’s possible to efficiently convert heat into electricity, but with very little power. It’s also possible to get plenty of electrical power — what is known as high-throughput power — from a less efficient, and therefore larger and more expensive system. “It’s a tradeoff. You either get high efficiency or high throughput,” says Hagelstein. But the team found that using their new system, it would be possible to get both at once, he says.

    A key to the improved throughput was reducing the separation between the hot surface and the conversion device. A recent paper by MIT professor Gang Chen reported on an analysis showing that heat transfer could take place between very closely spaced surfaces at a rate that is orders of magnitude higher than predicted by theory. The new report takes that finding a step further, showing how the heat can not only be transferred, but converted into electricity so that it can be harnessed.

    A company called MTPV Corp. (for Micron-gap Thermal Photo-Voltaics), founded by Robert DiMatteo SM ’96, MBA ‘06, is already working on the development of “a new technology closely related to the work described in this paper,” Hagelstein says.

    DiMatteo says he hopes eventually to commercialize Hagelstein’s new idea. In the meantime, he says the technology now being developed by his company, which he expects to have on the market next year, could produce a tenfold improvement in throughput power over existing photovoltaic devices, while the further advance described in this new paper could make an additional tenfold or greater improvement possible. The work described in this paper “is potentially a major finding,” he says.

    DiMatteo says that worldwide, about 60 percent of all the energy produced by burning fuels or generated in powerplants is wasted, mostly as excess heat, and that this technology could “make it possible to reclaim a significant fraction of that wasted energy.”

    When this work began around 2002, Hagelstein says, such devices “clearly could not be built. We started this as purely a theoretical exercise.” But developments since then have brought it much closer to reality.

    While it may take a few years for the necessary technology for building affordable quantum-dot devices to reach commercialization, Hagelstein says, “there’s no reason, in principle, you couldn’t get another order of magnitude or more” improvement in throughput power, as well as an improvement in efficiency.