using a thermoelectric module on a rocket mass heater ??!?

I did a search on permies & found nothing on  thermoelectric module. That does not mean it not here, just that I did not find it.
I read an article on  thermoelectric module in Low Tech Magazine: https://www.lowtechmagazine.com/2020/05/thermoelectric-stoves-ditch-the-solar-panels.html
And came here to see if it was something that would be worth the cost of added to a heater.
The RMH & hybrid poplur can keep a small homestead warm for years, so would adding the Module be worth the cost in the long run.
Also would it cause more problems than it solved, which is an complaint of solar panels & no I do not have an answer.
What do you think?

using one to power a little stove fan (à la an ecofan) might be cool.

Joe,

This is one of those great “is it worth it” questions.  Certainly you can configure TEG’s into a RMH, and TEG’s reliably generate electricity, but their efficiency is mediocre, meaning they don’t generate much electricity even under optimal circumstances and they don’t come cheap.  I looked into this strictly out of curiosity, and the best setup I found could produce 100 watts of electricity by using high temperatures and water cooling and the module was not cheap.

This is not to say that you can’t do it.  If you are really interested, or want a robust, reliable power supply when power is out, this might be for you.  You might consider Tegmart.com.  They have a pretty comprehensive list of modules and equipment, but again, they do not come cheap—just fair warning.  If memory serves, we are talking about hundreds of dollars for a 100 watt module.  

This would be a very interesting project, and if you decide to do it, please keep us updated, I think it would be VERY interesting to see how things work out.

Good Luck,

Eric

I just checked Tegmart and their best product, a 100 watt water cooled unit runs $717.99 and is currently out of stock.

Eric

I suspect a TEG is better suited to a traditional wood stove than to a RMH.  I think they tend to like moderately high temperatures and the longer that temperature is available, the longer you get electricity.  

I don't know if they'd work at the temps of a RMH bench.  They'd likely work at some place on the barrel but that temp is only available for a few hours a day.  Whereas a wood stove may be hot for 12+ hours a day.

Mike is correct about the optimal working heat.

The 100 watt TEG I priced likes a hot side temperature of over 700 degrees F.  This might work on the barrel of a RMH, but not the bench.  I am afraid that for these to work the temperature differential needs to be quite high.

Eric

a stove fan would cool the heat exchanger. that might marginally improve the performance of the heater by increasing the draw.

Joe Grand wrote:I did a search on permies & found nothing on  thermoelectric module. That does not mean it not here, just that I did not find it.
I read an article on  thermoelectric module in Low Tech Magazine: https://www.lowtechmagazine.com/2020/05/thermoelectric-stoves-ditch-the-solar-panels.html

Hi Joe,
I read the same article and thought about posting a link here, but I see you already did that.
I love that the server that runs lowtechmagazine.com is solar powered.

As for efficiency, did I read it correctly that the heat that is used by the TEG is then given off again, so in a way, the efficiency is actually close to 100%?
If you're running the stove anyway for heat, and you have a way to store the energy produced, why not use a TEG to capture some of it?
I guess like anything, you'd need to figure out the break-even point on the initial setup costs.