# peltier module power



## Efiero (Feb 7, 2009)

why doesn't any one try putting a bank of peltier modules to gather and use hot fluid to heat one side and cool fluid for the other to make electricity to run a electric car then all you have to do to recharge is reheat the fluid or replace it with hot fluid. i think to reheat you would use a induction heater as it would be the fastest way to reheat . i know NASA uses Peltier modules to power their rovers but they use uranium to heat the hot side


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## Ziggythewiz (May 16, 2010)

Efficiency and scale. Not all of us have access to nuclear reactors and we don't measure traction power by the watt.


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## jeremyjs (Sep 22, 2010)

peltiers are very inefficient devices.


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## Efiero (Feb 7, 2009)

no need for nuclear reactor i was just thinking a tank of hot molten salt to store energy and efficiency is low on the peltier so it would take a pretty big bank of them


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## jeremyjs (Sep 22, 2010)

Efiero said:


> no need for nuclear reactor i was just thinking a tank of hot molten salt to store energy and efficiency is low on the peltier so it would take a pretty big bank of them


theyre also quite expensive.


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## Ziggythewiz (May 16, 2010)

The main point of an EV is efficiency. 

Pouring gasoline all over yourself is probably more efficient and safer than pumping molten salt.


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## jeremyjs (Sep 22, 2010)

and when I say inefficient I'm not talking 40-50%. More like 7-10%. I think GM even has a design and patent for a peltier thermoelectric generator for the exhaust on an ICE car; since most of the power is still present in the hot exhaust gas; because of how inefficient the ICE is. They shelved it; becaus you couldn't pull enough from it to completely replace the alternator and it would have added thousands to the cost of any car it was put on.


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## PStechPaul (May 1, 2012)

You can get Peltier modules on eBay pretty cheap. I bought this pack of 5 for $30:
http://www.ebay.com/itm/370448335146
They are 127 watts each, 635 total, so less than five cents per watt. If they are 5% efficient, it's about $1/watt. Cheaper than solar cells. I've seen youtube videos where people have put them on wood stoves and they get enough usable power for basic lighting or small appliances, or just store the energy in batteries to supplement the solar panels. Run the wood stove at night or on cloudy days when solar panels are useless.





 
I haven't actually used them yet, but they seem OK.

There are also some cheaper Chinese units, but I trust these more.

The hard part is maintaining the temperature differential, but I think the way to do it is to run cold water through a heat exchanger, and when It gets too hot, use more cold water (maybe snow?), and you will also have hot water you can use as desired. 

It would take a lot of Peltiers to power an EV, although maybe a small tractor. For 2 HP you need 1500 watts actual power so at 5% efficiency you need 30,000 watts, or 236 modules at $5 each. So about $1000. But 30,000 watts of heat is about 100,000 BTU/hr, or about the capacity of a large woodstove.


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## jeremyjs (Sep 22, 2010)

they've certainly gotten a lot cheaper. Still the efficiency makes them all but unuseable for an EV. Not to mention the idea of carrying around molten salt...


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## nat_ster (Oct 19, 2012)

Cool info.

That would be a good way of making light for the remote cabin.

Nat


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## jeremyjs (Sep 22, 2010)

PStechPaul said:


> You can get Peltier modules on eBay pretty cheap. I bought this pack of 5 for $30:
> http://www.ebay.com/itm/370448335146
> They are 127 watts each, 635 total, so less than five cents per watt. If they are 5% efficient, it's about $1/watt. Cheaper than solar cells. I've seen youtube videos where people have put them on wood stoves and they get enough usable power for basic lighting or small appliances, or just store the energy in batteries to supplement the solar panels. Run the wood stove at night or on cloudy days when solar panels are useless.
> 
> ...


Out of curiosity, did you order the high temperature type? I was looking; because this post got me interested in looking again. All the high temp modules I found were still fairly expensive. The standard ones are only good up to about 100 deg. C. There are high temperature ones that are good up to over 300 deg C; which actually would be good for something like you posted, but all the ones I found are quite expensive.


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