Energy harvesting IC...

[Demon]

... I pulled out one of my peltier devices. Mine has heat sinks on both sides, so you may be able to generate more electricity with just a bare peltier using this method. I was able to get to about 1.025 Volts using hot tap water in a Ziploc ® one side, and an ice pack on the other. Total guess of about 100 degrees difference. I was sort of hoping to see a little more volts out of this one.

Walter

Ok, so now you got me curious too. Can you elaborate on the peltier, never seen one. Pics?


Shoot, if temperature differences can generate energy, I live in Quebec. I can stick a few of these in some windows during winter.

Come to think about it, you can also use it in reverse during summer; one end outside, one end going a few feet deep, maybe into concrete a few feet underground.

EDIT: A quick google got me this:

http://en.wikipedia.org/wiki/Thermoelectric_generator

Thermogenerators are devices which convert heat (temperature differences) directly into electrical energy. For the most part, this term is synonymous with "thermoelectric generator" (TEG) and rarely used in English. Essentially they work on the principle of the Seebeck effect, with typical efficiencies of around 5-10%. Older Seebeck-based devices used bimetallic junctions and were bulky while more recent devices use bismuth telluride (Bi2Te3) semiconductor p-n junctions and can have thicknesses in the millimeter range. These are solid state devices and unlike dynamos have no moving parts, with the occasional exception of a fan.


EDIT SOME MORE: Ok, after seeing mention of TEC, I remembered seeing that term somewhere before, this is what I use to cool the cpu in my gamer pc:

http://www.legitreviews.com/article/491/1/

[ScaleRobotics]

Hey Robert,

That's pretty much it. The short description of a peltier is :A Peltier cooler/heater or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other.

Some cars with heated/cooled drink holders use them, and some mini cooled coolers use them. Reverse the polarity, and you reverse the side that is hot. In astronomy cameras, they stack them to get the camera imager really, really cold. That way they can take 20 minute exposures without very much noise.

Maybe a device that was made to generate thermo electric power would be able to generate more power. I used a cold pack on one side, and the hottest tap water I could get on the other, but I was only able to generate about a volt. Not very efficient for about a 100 degree difference. I had hoped it would have been another volt or two out of it at that temp difference.

Here is a picture of what I used, and then the actual device:


And just a peltier normal device without heatsinks:

http://search.digikey.com/scripts/Dk...me=102-1668-ND

This explains a little more about them, and their inefficiencies.
http://en.wikipedia.org/wiki/Thermoelectric_cooling

[Demon]

Did you check the datasheet for your model?

It's talking about 3A 15.4V max at delta Tmax 66c @ 27c.

Ok, so I'm not sure how to interpret all that, but is it possible that you went over specs by going up to a 100c difference?

[ScaleRobotics]

Did you check the datasheet for your model?

It's talking about 3A 15.4V max at delta Tmax 66c @ 27c.

Ok, so I'm not sure how to interpret all that, but is it possible that you went over specs by going up to a 100c difference?

Thanks Robert,

I was working in the 100 degrees F range.
I don't really know which model mine has inside it. I probably would get more voltage at 150 degrees F difference. But in a real world scenario, it would be hard to produce this naturally I would think. Other than placing one side of it on my muffler or something .... and then I could just use the alternator.

Mine is better suited for building a 12 to 15 volt dc refrigerated cooler. I think that is what mine was originally built for. I bought mine at a surplus electronics store.

Walter