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Electricity Generating Heat Engines

Post in 'The Green Room' started by jebatty, Nov 2, 2011.

  1. jebatty

    jebatty Minister of Fire

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    This may be a conference to watch. Many of us are interested in generating electricity in non-traditional ways, including use of wood to generate the heat. For those of us using wood for space heating and DHW, electricity generation would be very desirable add-on.

    Heat Engines

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  2. Jags

    Jags Moderate Moderator Staff Member

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    Jim - I have been a fan of this idea for quite a while. I really wish some kind of "breakthrough" would happen. Currently the most effective use of heat for electricity is still steam generation, that I am aware of.

    Wouldn't it be cool to have a plate that could slap to the side of your stove and generate some wattage?
  3. karl

    karl Minister of Fire

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    I think for the average guy, an internal combustion engine fed with wood gas would probably be the easiest.
  4. billjustbill

    billjustbill Member

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    Electricity directly from heat... Neat idea. With more R&D for larger scale and cost effectiveness, it has some potential for wood burners like us....

    http://www.tegpower.com/index.html
  5. begreen

    begreen Mooderator Staff Member

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    Thanks for posting Jim. I've got to start playing with this. Time to move beyond the ecofan.
  6. Hunderliggur

    Hunderliggur Minister of Fire

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    The liquid system looks the best for boiler owners. The derated cost is about $20/watt. Solar PV is now available in the $1.50 to $2.00/watt range. Worth keeping an eye on. Since it is a Delta-T device, running on boiler output is probably more efficient than storage, but solar is a good heat source too.
  7. begreen

    begreen Mooderator Staff Member

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    I'm curious about experimenting with this because the sun doesn't shine 24/7 here, or even at all many days in the winter. But the stove is running.

    Including shipping I get $5.8/w with this panel, is that incorrect?

    http://www.tegpower.com/pro3.htm

    and this unit claims 92w for $5.49, though I am not sure what the heat side power output is yet. 1 watt?
    http://www.amazon.com/TEC1-12706-Thermoelectric-Peltier-Cooler-Volt/dp/B002UQQ3Q2/ref=pd_sim_e_1

    I'd have to operate it bellow 100 °C but that should be possible with a good heatsink on our stove's rear heat shield or perhaps on a section of double-wall pipe?
  8. Jags

    Jags Moderate Moderator Staff Member

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    15 V DC at 1 amp max. So if you had 15 of these things running at the 260C temp (500F), you could run a friggen headlight from a car with them. That is pretty impressive, but for some reason I am hesitant. Something doesn't add up in my head and I don't know what it is.

    Edit: I did notice that they will require external cooling from air or liquid.
  9. Delta-T

    Delta-T Minister of Fire

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    teg and stirling engines both suffer from the same drawback....must sustain the temp differential and they pretty much have to be disigned for a particular differential range. Both of these will work great in outer space.....I'm just having trouble figuring out how to run the extension cords.
  10. begreen

    begreen Mooderator Staff Member

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    I'm thinking on a woodstove system, the differential is there between the stove top trivet or flue pipe and say a cooler inline with an OAK. Design a fluid transfer system and power a small, efficient dc pump to keep it cool.
  11. Delta-T

    Delta-T Minister of Fire

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    may not even need the pump....thermo syphon loop might work well enough. Using the OAK is a very sharp idear.
  12. begreen

    begreen Mooderator Staff Member

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    Yeah, I would prefer a passive system. Will have to play with that one. I may do an initial test in the greenhouse. It has a much colder ambient temp.
  13. Jags

    Jags Moderate Moderator Staff Member

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    There it is!! That is the part I was missing. The energy consumption of maintaining the proper temp differential. I think if I remember correctly that it takes almost as much energy to maintain the temp diff as the item produces, leaving a small gain. Hmmmm... I like your cooling idea BG. If a system could be done with very low power consumption, you may be able to hurdle that part of the equation.

    Route the OAK to the t.e.g before entering the fire box??? Because the natural draft of the stove is free energy (so to speak). I'm liking it.
  14. mellow

    mellow Resident Stove Connoisseur

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    Thought this might be an idea to power my insert fan without having to run the power cord and also having it run during a power outage, it would effectively shut off the fan when the temp cools down as a bonus.

    Curious to see how this works for you guys.
  15. begreen

    begreen Mooderator Staff Member

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    The same thought came to mind mellow. Tied to a battery and an inverter this would be handy for pellet stove owners. But it would only extend the battery useful period for a while. A basic 30watt system at 12 volts is supplying less than 3 amps or a generous trickle charge. My thought was for led power outage lighting and a jack for a small 12v TV or radio.
  16. peakbagger

    peakbagger Minister of Fire

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    There used to be a firm in Iceland that sold liquid cooled TEGs. I cant find a trace of them anymore. They set up a thermosyphon loop to the outdoors to cool the TEG. If I remember correctly even in Iceland they had a touhg time getting rated output due to inadequate cooling.
  17. guy01

    guy01 Member

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  18. renewablejohn

    renewablejohn Member

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