# Using thermoelectrics in woodstove seminar



## peakbagger (May 4, 2017)

FYI. I got this invite thought some folks would be interested.

Do note, unless there has been a radical discovery, thermoelectric modules are not going to put out much power. The prior systems I have seen were in the range of 40 watts. Nevertheless it might be interesting


*Thermoelectric Wood Stoves*


Date and Time:* May 18, 2017 - 11:00 AM ET*


Presenter: *Gerard Campeau - President, Thermal Electronics Corporation*


Topic:* An introduction to thermoelectric generators and how they can be used to generate electricity from wood stoves.  *


Register:* https://attendee.gotowebinar.com/register/4144581975489425923 *


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## begreen (May 4, 2017)

They are a TEG company. The pitch is that they have a TEG capable of 100W output but i haven't found this product on their site yet. They do have 60w system that requires using recirc pump. The pump is going to use ~10W. At $629 it's not cheap, but if one is off the grid it could help charge a battery bank.
http://espressomilkcooler.com/thermoelectric-power-generator-systems-for-sale/


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## woodgeek (May 5, 2017)

Kool.  Do they have lifetime specs...as in run hours on the junction?


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## peakbagger (May 5, 2017)

One of these years the Dean Kamen design Sterling Cycle will hit the market and then I will start to think about generating power with a boiler or a wood stove. Considering he has been tinkering with it since before the Segway I expect its going to be awhile. It usually gets hyped every 5 years, so we are due for another round one of these days.

The Carnot cycle efficiency seems to govern both TEGs and Sterling cycle and it isn't great for a woodstove.


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## iamlucky13 (May 5, 2017)

Thanks for the notice. I'm interested, even though I get the impression it is likely to be a sales pitch as much as an educational seminar. However, I will be busy all of that day.

I'd like to tinker with using TEG's solely to run a small blower when the power is out, as our flush insert does not perform well without a blower. 50 Watts should be fine, and if I can get 4% efficiency, that's 4300 BTU/hour. That seems like a reasonable fraction of the heat from stove running in the 20-30,000 BTU/hour range.

I've got a couple really cheap units to play with, but haven't had time to start experimenting or do any heat transfer calculations.

One of the problems I'm expecting to encounter, aside from finding or learning how to create a power controller to deal with the variable voltage and current output, is high temperature TEG's seem to be extremely expensive, and conventional TEG's temperature ratings suggest they have to be insulated somewhat from normal stove-top temperatures. I've seen some affordable ($3/Watt) modules rated for a little over 600 degrees F, but that seems marginal at best

The host of this seminar seems to want $2600 for an 1100 degree rated, 23 Watt unit. His lower temperature modules have pricing in line with what I've seen elsewhere though.



woodgeek said:


> Kool. Do they have lifetime specs...as in run hours on the junction?



I've not found any life rating data, but...

The Voyager 2 spacecraft is currently within a few months of hitting 4 decades of continuous operation of its thermoelectric generators. Their current electrical production is about 54% of what they were at launch. Their plutonium heat sources should be producing about 73% of their heat output at the time of launch, so that means the thermocouples are working at a little under 75% of their original performance level. That's in the same ballpark as expectations for solar panels.
https://voyager.jpl.nasa.gov/spacecraft/spacecraftlife.html

However, the Voyagers experience effectively no thermal cycling, and I don't know if they use the same type of junction as the TEG's available at prices a household product might justify.



peakbagger said:


> The Carnot cycle efficiency seems to govern both TEGs and Sterling cycle and it isn't great for a woodstove.



TEG performance is no danger of running into the Carnot efficiency limit in the near future. None of the Sterling's I've seen data on are very close either, but they're usually a ways ahead of TEG's.


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## Picker (May 7, 2017)

Alaskan Theo Graber has worked on building a thermoelectric generator. Which uses a catalytic converter in the wood stove flue to increase temperature difference for better performance. I have been following his project for several years. Though not aware of a working prototype having been built?

Article: https://www.adn.com/energy/article/...turns-wood-stove-heat-electricity/2013/02/19/

Website: http://alaskadynamics.businesscatalyst.com/index.html

Facebook: https://www.facebook.com/AlaskaDynamics/


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## begreen (May 7, 2017)

Interesting concept. Wondering how they automatically bypass the cat during startup and how durable that would be at flue temps?


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## Picker (May 7, 2017)

Found this AEA Emerging Energy Technology Fund Grant Application today describing the project. 

http://www.akenergyauthority.org/Co...nd_2/Delta-T Wood Stove Generator Project.pdf


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## begreen (May 7, 2017)

Good info, thanks for finding this. The application describes little of the marketing feasibility which seems like it could be a serious impediment.


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