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for a wee bit.

 

 

uses include:
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RMHs and thermoelectric generators  RSS feed

 
Chris Ocampo
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Hey, so there there have been all kinds of these cool new camping type products that integrate a thermoelectric generator to charge phones n such while you're cooking your food. i was wondering if anyone had tried integrating any into their RMH. seems like a pretty simple and thing, and it would be a great alt source of energy in the winter when the solar is not as effective.

things like this. http://www.directive21.com/products/the-powerpot-v/
the thermoelectric generators seem fairly cheap too. http://www.ebay.com/itm/THERMOELECTRIC-POWER-GENERATOR-TEG-MODULE-NEW-USA-/310230284381#vi-content
 
Sandy Mathieu
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The ones like on ebay are ussually not suitable. TEG's have certain heat tolerances, and they are actually pretty low. Depending on your barrel temps will fry. Its to bad because the real electricity comes from the temperature difference. If you want to get a meaningful amount of electricity, it usually needs to be water cooled, and thermosyphon often is not enough. Then you have a pump and an entire little plumbing system. Now your TEG is getting expensive.

The best ROI is if your heater is going all the time, which while true of cast iron stoves, kinda against rocket mass heaters.

It might be possible to use cheap ones in the mass somewhere to drive electricity on a more continuous basis... but to me at this time. There is not a great marriage of price performance for a rocket heater environment.
 
Chris Ocampo
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i kinda figured the burn chamber would be too hot and was already thinking that embeded into the cob bench area would work better as the heat would be sustained for a long period. i'm more of an idea guy hoping to inspire an engineer type so i can replicate it.
 
Bill Bianchi
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Late to this party, but I'll throw this out and let members tear the idea to shreds or ignore it.

Here's an "impossible" idea for using a high-heat source (rocket stove or parabolic reflector) to power a fragile Peltier or thermoelectric generator module (TEG), which would normally be destroyed by the intense heat.

Use the parabolic reflector or rocket stove to heat water or oil ONLY to the Peltier or TEG's maximum working temperature. Use the hot liquid as the heat source to operate the little generator. If the maximum rated working temperature of the module is below the boiling point of water, use water. If over water's boiling point, use mineral oil.

Use a thermometer to monitor the liquid's temperature as the stove or solar cooker heats it. When it reaches the maximum working temperature of your specific module, remove the liquid from stove or parabolic cooker.

For the generator itself, sandwich the module between two square metal, liquid reservoirs. Pour cool water into the cold-side reservoir. Pour heated oil or water into the hot-side reservoir. The module should generate electricity from the difference in temperature between the two reservoirs. (If using it during winter months, use the outside temperature to further cool the water for the cold side reservoir. This will create a larger difference in temperature between the hot side and cold side of the TEG, which should help generate more electricity)

Because the hot side reservoir liquid is heated ONLY to the maximum working temperature of the module, there should be no danger of damaging the module with excessive heat. Because that liquid was heated by a heat source too extreme for direct heating of the module, you effectively have a means of safely using that high-heat source to operate a Peltier or TEG module, no matter how low the maximum working temperature rating of the module may be.

Sounds good, right? Not so fast.

Let me help tear this idea apart so no one actually tries this.

1. A generator like this would cost more than solar panels. Just buy solar panels and forget innovating or experimenting or looking for other ways to generate sustainable, clean energy. If it were possible, energy companies would already be doing it.

2. Unlike solar panels or wind turbines, this generator would require the home user to actively heat the liquid. Just stick to what is already easy and available. If something more green and sustainable is discovered, energy companies will gladly sell it to you and go out of business---for the good of mankind.

3. While a generator like this could function off solar heat and/or a rocket stove, making it an on-demand generator that is not necessarily dependent on weather conditions, the idea is just too different from what we're used to. New is bad and scary. Best not to mess with it.

4. Focus only on the downsides of TEG technology and ignore any so-called benefits. Yes, a person with a rocket stove burning bio-briquettes made from waste material or using a parabolic cooker could heat mineral oil and use that to generate electricity at home. Yes, these modules could be used tens of thousands of cycles with only a 3% loss of generating ability over time, assuming they're not damaged with excessive heat, possibly a person's entire life time. Yes, with no moving parts, a generator like this would operate as silently as a solar panel. Yes, a generator like this could operate with no harmful emissions, depending on the heat source used to heat the liquid. Yes, this technology can be clean and green and even reduce the waste stream going into landfills. Yes, anyone with the skills to heat liquid and read a thermometer could operate a generator like this.
But, for all that, it's not photovoltaics or wind turbines, now is it? No, best to forget about this technology, at least until elite, qualified individuals who have the credentials step in and either make this work or prove it to be impossible for practical applications in the real world.

I've been at this long enough to know I just wasted my time posting this. Nothing will ever come of it, nothing will change. I'm the poster boy for insanity, looking to do my part to help find ideas to change energy production to something more sustainable and less damaging to our environment, all the while knowing anything different than what we're currently doing will be rejected no matter what. Over and over, hoping that some day things will change for the better. Pure insanity. What I've learned is that humanity will go down in flames. It is just our nature.

Idiot out.
 
Glenn Herbert
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Requiring the user to actively monitor the liquid temperature and stop it when it gets to the maximum is impractical. Eventually, no matter how dedicated, the user will miss the shutoff and overheat the liquid, possibly damaging the system.

Better to design the system as fail-safe, i.e. so that it either cannot overheat or will not be damaged by overheating. That will require more thought and skill in designing, but would make the system practical to operate.

Cost feasibility is another matter, and requires careful analysis, including the value of having an intermittent but nearly automatic power source. The amount of power that can be generated vs. demand it is needed for is also critical. This factor may improve with improved technology and economies of scale, though it might not outpace improving economies of alternate sources.
 
Michael Robertson
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If a TEG is impractical how about a stirling engine? There has been a lot of discussion about Stirling Engines on other threads if you do a search of this site.

There are lots of sites where you can buy them or if you are skilled make one yourself. They can be made to be powerful generators or tiny engines running from the heat off the palm of your hand.

Some links:-

http://www.howstuffworks.com/stirling-engine.htm





http://dirtsimple.com/

http://www.stirlingengine.com/

I sometimes wonder if the principle behind the pumping action of the RMH is the same as the stirling engine. A kind of "solid state" stirling engine.
 
allen lumley
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Over in the Alternative Energy section there are displayed some current wrinkles in Thermo-electric power generation! Patented in 1816 nearly 200 yrs ago
the size needed to be able to extract useful amounts of ether horsepower, or watts has meant that as soon as we had anything that could reliably deliver
5 Hp the Stirling engine so became a Solution looking for a (very Small) problem, most everything on the market makes power in units of a few Watts !

Using the old 100 watt light bulb as a standard of measure almost all Stirling engines are not up to the challenge!

An even more accurate idea of just how far the sterling has to go- if you put the average American electric only use on a diet, most American would be
upset if they had to survive on 3Kw per day, twice what many western Europeans use.

Thats the equivalent of 30 full time slaves each requiring the Electrical energy of (1) 100watt light bulb !

With that for a measure, todays 'kit' Stirlings are just toys !

TEGs, here we have Waste heat recovery units that require narrow bands of heat energy that they can perform in After Some Heat Energy Extraction which
is successfully converted to Electricity, the TEGs own waste stream runs an exhaust gases temperature high very close to the boiling point of water !

We need a waist engine recovery system to run behind our waste recovery system, what we get is waste heat being vented to the Environment and Heat
Islands !

However- I am hopeful, though fusion power stands as good a chance today as many forms of Thermo electric generation to become a player in our energy
needs ! For the Craft ! Big AL
 
r john
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Bill

You will find I have mentioned this many times on Permies. it is an established technology which seems to be swept under the carpet every time it is mentioned. From a commercial point of view it does not make sense with efficiency of approx 6% when using the same hot thermal oil in a turboden generating plant has an efficiency of 22%.


Allen

The latest Stirling from europe is 5kwe constant and 10kwe peak load with multiples of that size available.
 
allen lumley
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Please allow me a minor recap of what I have found myself for an hours Google/Bing Searches on the internet ! I quickly viewed approximately 20 sites
by searching images and clicking on any site w/ a description of a 1.5 kw .generator or bigger ! The majority of sites had not beeb updated in several
years, with a sprinkling of 'site not found' bait and switch (Alibaba) and bad contact information

Two articles by some hack who didn't know he was describing a CHP with a I.C.E. power plant and waste heat recovery to residential heat and domestic
hot water and 3 other links back to that article, Solar mirror schemes with excessive costs !and unrealistic Brake horse power and brake horsepower to
KWe- general bad math!

I do notconsider myself in any way qualified to perform a quality search for more information, I am sure there are some units being produced
with subsidies to the manufacturer and the power companies just like the CHP offerings (I.C.E.s and heat pumps ). But- spare units available to be
shipped F.O.B. to a 2nd country for less than 10,000 dollars and offering a track record. I was unable to find even one!

Please if you are following the development of a commercially available build I am willing even eager to admit my error publicly! I am not looking to
purchase anything on the Market today !

Sometime I have a very funny story the starts of with my father telling me to never go out of my way to buy the 1st or the last of anything - and the day
I managed to do both at the same time !

I have often used these Threads to rail against the crap out there in You tube land, My latest search into the Field of Stirling engines never reached as
high as that low standard!

For the Good of the Craft ! Big AL
 
r john
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Allen

I dont post on here for the good of my health but to try and give another perspective from a european point of view as a lot of threads have a US bias which is expected due to the number of permies members from the US.

As you know the Whispergen stirling engine was an off the shelf CHP system sold in Europe for approx 5 years although I believe it went into administration after production was moved away from europe. I believe the new 5kwe machine is being built by a team that was involved in the original whispergen design.

This is a 9kWe stirling used throughout UK primarily at landfill sites where the gas flow has reduced to make conventional gas engines uneconomic.

http://cleanergy.com/wp-content/uploads/2014/06/cleanergy_brochure_chp_lowres.pdf
 
Satamax Antone
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R John, you also know that in euroland, we tend to invest often on pipe dreams or things which are too expensive. For example, in France, we have a train and a jet fighter, which are revolutionary. But can't be sold, because they're too expensive, and not in the market trend. That's the TGV and the Rafale. There's the Guy Negre compressed air engine. Suposedely works wonders, easily rechargeable, unlike electric ones. But that doesn't sell. I can't remember of the Brit or german failures like this, but there's some!
 
r john
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Satamax

I agree we have some very good engineers in Europe with staggering technology like Concorde and the Harrier jump jet the problem is its all very expensive so fails to get the volume sales to make it a product for the masses. I think Allen is unrealistic in expecting a high quality engineered stirling engine equipped for grid connection for under 10000 USD.
 
Satamax Antone
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One thing which poped into my head, when clicking to open this, "reliant robin"

Harrier didn't sell too bad! (and i love it, as well as the eurofighter) I think woodgas or biomass gas cogen plants are a better alternative than stirlings. But to me, stirling engines are just toys seen on the internet.
 
r john
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Satamax

I cannot think Reliant Robin without thinking "Topgear" and Jeremy Clarkson

I here what you say about woodgas but even that is more expensive than $10000.

I think Vulcan are one of the cheapest off the shelf and there 5kw is $14200 and thats without any grid connection capability.

http://vulcangasifier.wix.com/vulcangasifier#!turnkey-systems/cvr1

 
Johnmark Hatfield
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sorry for bumping an old thread that no one thinks will go anywhere. I just got done reading a book from the 70's about heating with wood and the author gets soooo close to RSMH's but eventually he just says that there will be no progress because everything has already been tried.

so i want to look at an old idea again. i found a site called customthermoelectric.com. it seems like a pretty serious site. ie: not just a junior high kids science experiment. There has to be a reason buying 100 of these is an option. Like. could they be put into a solution (as mentioned itt) and wired up in series, embedded in the mass of a RSMH. and go to a battery? they say they can take 600F. i have to get to work, but i'll be back.

it would be neat to just buy 20 of them and see what happened with them.

http://www.shop.customthermoelectric.com/1261G-7L31-04CL-Power-Generation-Module-1261G-7L31-04CL.htm;jsessionid=60EE15EC01DF9370B0D2D4BD825C6888.m1plqscsfapp04?gclid=CjwKEAiAx4anBRDz6JLYjMDxoQYSJAA4loRmwnV2QWu1jbQfVm0VwCzhIXGHNPHCqeyQNessC6WQ3hoC1pPw_wcB
 
thomas rubino
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Johnmark: I Looked over the site, Although I'm sure that you can produce power this way your outputs would be all over the board. Low voltage -low amperage. If I understand these correctly, they need a constant temp to give the rated output. You could... find a sweet spot on the outside of an un cobbed barrel that ran a temp of 600 F or less but that temp will swing down as soon as your fire slows down. Your mass is not hot enough to produce a usable amount of power . Running a rmh full time at max heat output would only be practical in a large uninsulated building. You would be using quite a bit of wood (at least by rmh standards) You would need to feed that fire every few minutes to keep it at max output. All that just to make a few amps or less at 12vt ! Not for me. Fun idea if you had these for free just to play with but... BUY 20-100 of these to make a few amps . Just not practical ! Instead buy one large solar panel and sit inside by your rmh and watch the sun make a few amps with much less effort on your part.
 
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