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Woodfired TEG generator - Yes, I'm crazy.

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Woodfired TEG generator - Yes, I'm crazy.

Postby James_Penrod » Fri Aug 26, 2016 7:56 pm

We heat our home in Detroit exclusively with wood. Furnace in the basement ( with two coils for heating water, one on the inside of copper for running in the summer time, very minimal wood is burned, and a PEX coil outside the furnace for winter running with the copper coil drained and disco'd for obvious reasons).

Been mulling over cost to benefit on various forms to go off-grid 100% with minimal need for an expensive battery bank.

Wind? Sure, it's windy here, but the city might mind 6 turbines on my roof. Only house on the block, but still....

Water generator? Need to drill a well first...and aquifer is a whole 'nother issue...

Steam? Already burning wood, add a little water and a few pieces of plumbing and a steam turbine and....yeah...ballistic speed metal through my living room floor.

So, I'm at Peltier modules.

I'm thinking of these: http://peltiermodules.com/?p=product The TEC1-12730HTS to be specific.

Now, if I run 39 of these, external to the woodburner, and send a tube through the heat exchanger to gather my hot side temps, and adjust that air temp with a small DC induction fan switched to the same thermostatic switch for an RC car servo to damper in cool air to maintain the proper operating temp, and running water at approximately 14 to 20 Celsius over the cool side, then run all of that through a few pure sine way inverters....

Shouldn't I end up with around 4kw ( or 200amp @ 120volts AC )?

Mind you, I'm no engineer, but I know my way around a soldering iron. Built my own WiFi CCTV system from Raspberry Zero computers and a few components.

I guess my approach to this is just "Use a bigger hammer", but it looks like for less than $800USD I can go offgrid and just maintain my municipal connection as a back up in case I don't get up early enough to reload the furnace.

Any thoughts?
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Woodfired TEG generator - Yes, I'm crazy.

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Re: Woodfired TEG generator - Yes, I'm crazy.

Postby techman » Mon Aug 29, 2016 4:09 pm

If you can afford all these and you can keep the cool side cool then yes it should produce a nice amount of energy.

The toughest part is to keep the cold side cool. The cooler the cold side is, the more power you produce.

Hope this helps some.

One day I hope to build a smaller one using computer parts to see how it goes.
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Re: Woodfired TEG generator - Yes, I'm crazy.

Postby James_Penrod » Mon Aug 29, 2016 4:34 pm

Using the modules in the link in my original post would run about 200$USD (where I am). If my math is right (again no engineer) once all that median line DC is run through pure sine inverters I should have the equivalent of a standard 200 amp house supply at 120v and still be able to 240v any cooktops (nothing else is 240v and the cooktop is a backup in case I don't feel like building a fire for the indoor wood grill to boil water for morning coffee).

Though, since I entered the original post for approval, I've re-thunk using a mineral oil heated radiator on the hot side, and if the groundwater (also in a radiator) can't cool it down enough....well then, I'll slap a few peltier modules on THAT and chill the water even further.

I was heartened to find an article about these people: http://www.hi-z.com/ and their Patent for Quantum Well Thermoelectric Modules https://www.google.com/patents/US7400050 and their experiment with 1kw and 5kw models for military vehicles http://energy.gov/sites/prod/files/2014/03/f9/2004_deer_bass.pdf

Now, granted these are QUANTUM WELL thermoelectric modules and they are much, much more efficient and faaaaar less finicky about high end operating temps....these are for military applications....they have to be durable and be able to be somewhat ignored, so high thresholds are expected.

But, and it's a big but, this is merely a Bigger Hammer method I'm trying to attempt. If it's only $200 in modules, another $40 in shipping, a couple of $30 radiators, a few switches and relays, servos and maybe a tiny single computer like the Raspberry Pi, and two big-get-all pure sine wave inverters....then isn't a little under $1,000 and a few weeks tinkering worth it?

I'll be documenting everything as I go, including all testing data, blah blah blah. It's not going to have pretty graphs and such, but I'll be able to present everything in a comprehensive manner.

Fingers crossed....
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Re: Woodfired TEG generator - Yes, I'm crazy.

Postby techman » Sun Dec 11, 2016 10:06 am

Any updates on your system?
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Re: Woodfired TEG generator - Yes, I'm crazy.

Postby techman » Sun Dec 11, 2016 10:07 am

Someone recently sent us a TEG powered fan that sits on the wood stove and silently blows hot air through the house. I love it!!
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