grahamk
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|  | Thermoelectricity from stoves
« Thread Started on Feb 8, 2012, 11:11am » | |
I'm developing a technique for producing a little electricity from stove waste heat as cheaply as possible.
Is there anyone else working in this field?
GrahamK
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Donkey
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| | Re: Thermoelectricity from stoves
« Reply #1 on Feb 9, 2012, 6:28pm » | |
Yep.
Look up the T.E.G.
Thermo-Electric Generator.
Also, there's the Stirling Cycle Engine, which has been around for a LONG time and some folks have used them for converting waste heat to kinetic energy and/or electricity.
Seems to me that if the intent is to make electricity, the TEG or some kind of thermo-couple would be the way to go, fewer conversions.. On the other hand, if the intent is to use the electricity to turn some gizmo or provide some kind of kinetic motion, the Stirling Cycle would be my choice for the same reasons..
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karl
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| | Re: Thermoelectricity from stoves
« Reply #2 on Feb 10, 2012, 5:30am » | |
The efficiency of a TEG is typicaly just around 5-10%
and very small amounts of watts are produced.
TEGs for driving a blower or producing a bit light are relatively cheap.
A small Stirling has an efficiency of around 15% to 30%
and much larger amounts of watts can be produced.
A Beta Stirling would be the cheapest to build stirling.
Even a Beta Stirling is expensive to build, at least as high temperature version.
http://en.wikipedia.org/wiki/Thermoelectric_generator
http://en.wikipedia.org/wiki/Stirling_engine
In Germany the power companies are forced by law to buy electricity from everyone
at a good price, thus generating electricity from waste heat is of great financial interest
for homeowner.
One can buy here stoves with an build in Stirling to raise overall efficiency to near 90%.
The other way round is also common, using an Otto engine to produce electricity
and heating the house with the waste heat.
This third possibility is the most promising for producing a significant mount of electricity
with a wood stove. Parts of the gas produced by a gasifying stove could be used to drive an Otto engine. There are Otto engines of any imageable size.
An Otto engine is much cheaper to produce as a TEG or Stirling of a comparable power.
It would not need any control for varying rotation as it could always run in the most efficient range. One from the Waste could be used to.
Even a steam engine could be used, maybe the cheapest way.
http://www.john-tom.com/html/SteamPlans.html
http://npmccabe.tripod.com/steam.htm
http://www.animatedengines.com/oscillatingsteam.html
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woodburner
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| | Re: Thermoelectricity from stoves
« Reply #3 on Feb 10, 2012, 12:54pm » | |
Feb 10, 2012, 5:30am, karl wrote:
Steam is appealing as the engines are usually quiet and they are interesting to play with. The big problem is that they mostly use pressurised boilers, and these are dangerous and often kill people. One of the reasons for the invention of the Stirling engine.
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karl
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| | Re: Thermoelectricity from stoves
« Reply #4 on Feb 10, 2012, 2:35pm » | |
Quote:Posted by woodburner on Today at 12:54pm
One of the reasons for the invention of the Stirling engine. |
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Can be build even from a pringles box and a low energy generator can be cheaply build with solenoids.
On that can run 7/24 at higher temperatures and do some real work is more challenging.
There are reason, why most of them are just models.
Some infos, links and plans.
http://www.bekkoame.ne.jp/~khirata/indexe.htm
A beta Stirling with a solenoid generator for a little energy would be relatively simple to build.
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