Electricity from Waste Heat

Discussion in 'The Projects Forum' started by wayneh, Jan 25, 2011.

  1. wayneh

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  2. jpanhalt

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    That's impressive. I have an almost endless supply of wood for heat (outside burner; hot water system). It would be nice to run the circulator pumps from it too. I need about 2/3 to 3/4 HP total.

    John
     
  3. wayneh

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    A Peltier or TEC can be run in reverse to make electricity from a heat differential. It's terribly inefficient but does work. You'd need a big one or a gang of them. It actually might be possible, although wind or solar might be more practical for you, or even a small steam-powered generator. The reported technology may be years away from commercialization, even if it works as advertised.
     
  4. jpanhalt

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    Already looked into and discarded the Peltier/TEC approach. Hot -air engines (e.g, Stirling) were also considered, but an engine capable of 1 to 2 KW is quite large. A little like cold fusion, people are always saying they have something that will be produced next year. I follow the hot air engine Yahoo site.

    Solar and steam are the two technologies I am considering. I am a little reluctant to get into steam because of the risks, but like its on-demand nature, size, and longevity. Solar isn't without its issues either. Fortunately, NE Ohio is relatively free of hail -- we also have a lot of greenhouses for that reason. Third option is to grow something, sell it, and buy the electricity. A hunting club with dues would easily pay the cost for running the circulators in the Winter and provide food to the needy.

    John
     
  5. Kermit2

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  6. jpanhalt

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    Cute! John
     
  7. wayneh

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    Yes, several horsepower. You previously mentioned much lower HP needs.
    If you're able to connect easily to the grid, it's tough to beat those economics.

    That solar steam engine is a tried and true approach. I can see he built in a latitude adjuster, and the parabolic shape makes it unnecessary to worry about following the sun. Cool.
     
  8. jpanhalt

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    Please pardon my sloppiness. I have never seen a Stirling that produced much more power than enough to overcome its friction. The aforementioned site gave some examples of 500 to 1000W (I don't remember exactly) engines that were quite large, meaning physically large. As I recall, they were larger than a typical refrigerator. John
     
  9. Bernard

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    Remember Minto's Big Wheel?
     
  10. thatoneguy

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    From the applications mentioned, the device appears to require a rather large temperature gradient to produce power. I would even guess that "automobiles" was tacked onto the list for better promotion, as other areas for use would involve >300°F temps on one side, with the other being cool.

    Sounds mostly like an improved a bi-metal type junction (with ceramics), or an improved peltier design.
     
  11. kcarring

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    I have about 10 of thos epeltier module 40mm x 50mm. As a first experiment, I placed them on a cold window (northern climate). It hasn't been too cold here, it hovers the freezing mark outside, and inside, well... room temperature, we'll say. I see about 20mV output per module. It didn't make me run off to grab the battery bank, let's just say that much. I think you need a consistent 200 degree differential to see any real potential. As for the current, I don't know. I added up 25mV x 10 modules and decided that I didn't own anything that would operate on that low of a voltage.
     
  12. kcarring

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    Sterling motors are ridiculously low power, don't even waste your time there, until someone revolutionizes that industry. Steam turbines on the other hand are great, but complicated and expensive. There has been an interesting resurgence in "steam engines" (not turbines).

    i love this one, and it sounds like a little harley too :)
    http://www.youtube.com/watch?v=G3E2tv8UgfU
     
  13. kcarring

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