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For some time now I have thought that a Stirling engine would be a
good item for the back woods, that being defined as anyplace that
does not have electricity or a ready supply of fossil fuel.
My suggestion is a Stirling engine intended to be fueled by local
combustibles (wood, buffalo chips, whatever). The configuration would
be boxer, with a tank on the cold bank for water cooling and a firebox
on the hot side. The engine itself would be magnetically coupled so
there would be no shaft seal (a definite no-no in some areas). Power
output would be in the 10 to 25 horsepower range, enough to do some
simple farm work. To run it, just pour some water in the cold side
and build a fire in the firebox. It'll run on anything that will
burn. With a lot of mounting ears and flanges, it could be used for
either stationary or mobile applications. Build enough safety
features into it so it won't run away and disintegrate the flywheel if
the load goes away. Include a reservoir for working fluid (helium?)
to allow at least ten years of operation without requiring service.
The idea is to provide a single box that provides mechanical power
from heat.
Then simplify the design, build it in the target countries to take
advantage of the cheap labor and give the locals some jobs, and sell
them to the guys int he back woods. The test market could be the
American outdoorsman - make it into a really quiet fishing boat motor
and include an alternator to provide electricity for the cabin without
scaring the elk and moose away.

Any ideas on how to make this affordable?

Phil this really is a great idea, all except for the notion of selling them to the third world. The third world wants what the first world has. Saying that a product is good for someone else is another way of saying "I don't want it."

But your idea of selling such a product to the American outdoorsman is perfect. Particularly the American "rich" outdoorsman.

The development for this kind of thing is agonizingly time consuming. I suppose the somewhat glib answer to how to make this affordable is to keep development costs reasonable and don't really go "high" tech with the engine. Build a 100 psi air pressurized, wood (or whatever) fueled engine out of as much cast iron as possible with as few pieces of high temperature alloy as you can get away with. Integrate the engine into a wood stove.

The idea would basically be to apply modern thermodymaics to a relatively low tech relatively low cost engine. But it still will cost more when first produced than a Honda generator.

I have been profesionally working on this problem and related issues (part time) for the last twenty years.

After so much research - there are viable answers.

Please contact me if you would like to discuss this further.

What are the factors that make this difficult to implement? I've seen a model solar Stirling at http://www.pmresearchinc.com/solar03.htm and I'm curious to know what keeps such technology from being used on a larger (at least home) scale to produce electricity? Is it that such a Stirling wouldn't produce enough power to power a generator? Is it that efficient Stirlings aren't built yet or that there are mechanical problems not yet overcome? Is there any place to read up on issues related to Stirling manufacture and performance? Is there any company which mass produces Stirlings capable of work of the magnitude of small engines?

Thanks in advance for any information...

The model from PM research cannot easily be scaled up. When you build a more powerful engine you need to build a much different design, you don't simply buy a small one and scale it up. People hated having 6 to 10 foot diameter C band satellite dishes in their back yards, but they could at least get color television from a satellite 24 hours a day seven days a week so a lot of people put up with large dishes.

A basic solar Stirling engine would only produce power in the daytime on sunny days. Do you think that people would put up with a dish that only made power on sunny days? Besides that a solar Stirling engine would be competing with solar cells and building a machine to compete with a solid state device has usually (but not always) been a losing proposition.

What needs to be developed is a solar/natural gas Stirling generator. It would make power from the sun when the sun is shining and have a burner that would power the engine at night and on cloudy days. Unfortunately as wonderful as this kind of machine would seem, most suburban housewives would not like having it in their flower gardens.

Of course there would be some market for such a machine, since suburban housewives tend to stay away from hunting cabins.

The FAQ discusses the great lack of Stirling engine manufacturers.

I been thinking about this issue for a long time ,first ,I would use a 3 cyl. machine conected to sun panels and using buthane (presurised )as medium ,cyl block & head made out of teflon ,suitable to pump up well water who would be used for irigation and to cool the butane ,rev control by changing the inlet valve timing ,no out valve as the machine would run as a two stroke ,venting to the crankcase ,who is a butane reservoir and is cooled by the pumped up water ,machine completly sealed by overpressure from the buthane ,magnetic coupling with the pump .
suitable for raising crops ,lawn irrigation ,drinkwater for livestock in dry areas ,
Looking forward to Your opinion
Regards Herm

Attention has led this one to this group of people. It has also recently created excitement about Stirling Engines, WimsHurst Electrical Influence Machines, Hobbyist who are wonderful Small Machine Builders, the Van Arsdell Stirling Engine , NASA with a Pressure-Driven Magnetically-Coupled Conveyance, and even a web page at the Museum of Unworkable Devices. The power of ignorance is like the power of a vacuum. It allows insight to appear. Currently one is setting up a small home lab to start constructing a prototype of a power source. What it will be is not known yet. How could it be? It has not been built yet. The American story is threaded throughout with invention. Everywhere you look in our history it is there, and if examined, one sees ideas built upon ideas, until the known appears. You guys are here, there is a guy looking for investors and collaboration, the forum on the small engine building hobby site, and this wonderful global library called the Internet. Anyway, being a worker bee, the lab has to fit in as a small passion when time allows. Going to see if one can get a copy of NASA's patent drawings for their Magnetically-Coupled Conveyance. Build a small database of contacts, others with interest. Collect ideas, see what works, how to improve, modify. The world needs a free power source, before it is burned away. It would be wonderful to draw other minds and their insights into this problem. The equipment will arrive in just a few weeks and new contacts are forming. Thank you for being here.

I think the first problem here is how much an engine like that can cost and how much power can it produce compared to an Steam engine , places like Brazil and the whole South America are very rich in water suply, rivers, I've seen in distant locations watermills generating power to a refrigerator and for small houses, and this was made with single and non technology sistems with auto parts, car generatos and even wheels . We must never forgot that an thermodinamic engine aways needs a hot and a COLD suply of energy and sometimes we spend all the good energy that we produced just to cool the cold end and keep the engine working, I never reached a good ( over 50% ) profit in large gas engines not even theoretical by this reason,(of couse without heating up a river or a lake) . The great idea of an Stirling engine for the third world is to make small and reliable generatos for camping, fishing and sailing but this is for a small part of the population tha can buy this tecnology.

About Solar , as long as we have problems on captation of the solar radiation ( low profit on it ) we shoud think about using fuels to run it.

I agreed totaly to Brant's answear to this question.


if is there anything I can do , you all feel free to contact me.


Thanks
Ricardo

( and sorry about the english mistakes that you will probably find )

Hi.
Sad, Good ideas are not always commersial. Not in the start. I think (like a lokal polititisian and in selfemployd bussines i am) that a part of the solution to introduse the generator to 3.world, is by implement it to a eksisting program, like Red cross or CARE and more. Prinsiple of selfhelp polisies is sentral. WorldBank could play a roll, next to a 3.world org.

One comment about solar energy capture- modern vaccum insulated glass tubes with appropriate heat absorbers can exceed 90% efficiency of absorbtion from solar, and work on infrared as well as visible light. Temperatures of 250 deg C can be achived. This is far better than PV..use the heat for Stirling conversion to electricity and what sort of overall efficiency can one expect?
Steve Cox