Practical Use

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Practical Use

Postby anthonygonzalez1 » Fri Feb 06, 2009 12:53 pm

Subject: Practical Big Application

I have a real question about end use.

I am a database programmer and but I have never had the opportunity to
study mechanical engineering and it is a subject I like. Never the
less, I am ignorant to the math and technical difficulties on subject
matter such as these engines, but I still think I understand enough to
wonder about why we don't see practical applications of these engine
in daily use.

Wiki Answers had a post of a home using an average of 4,400 watts a
day. Lets assume their an eco-nut and a real home spends near 7 to 8
Kw a day. Can a Stirling engine be built, or perhaps two, and placed
in ones backyard, hooked up, and run your home? I have seen posts of
10 Kw Stirling engines in the past and it just seems like a LTD
generator would work just about anywhere, and a small wood burning pit
could be an emergency source of temp differential, if it ever came to
that.

Why don't we see this, if not at the very least in hobbyists, on some
commercial level? I assure you that if people could buy a machine that
let them get off the grid most of the time, at reasonable cost, they
would be busting down the door in hotter and colder climate areas of
the States and Europe to buy one. You can still be plugged into the
grid for those moments when a machine breaks or needs servicing, and
you always have power. It just doesn't make sense, so I must be
missing the big picture here with these engines.

What prohibits the technology from entering into the commercial market?
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Practical Use

Postby stan.hornbaker » Fri Feb 06, 2009 3:20 pm

Anthony: Please take the time and effort to read some of the previous posts. You should find answers to yours or similar questions.

The short answer to your last question: It is not economically feasible!
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Response to Practical Use

Postby craig___4888 » Fri Feb 06, 2009 5:28 pm

Hi Anthony,

I agree, with you, I am also a Db Developer, and hobbyist Alt Energy enthusiast. I am sure an engineering company could make one of these engines for around $7-12k, and this would totally be economical.

The 25Kw machines they are making for California Eddison, SES http://www.stirlingenergy.com/ look like they would cost around $100k ea, maybe less in the bulk.
Surely the majority of the cost is the Mirrors?
So, what if someone, say the Automotive industries that are going under started producing the engines in bulk, for households, at 10Kw or even 5Kw. Then they could be brought down to a more reasonably cost for individual households.
How many households are there in the USA? In Australia where I come form there isn't many... but in the USA... .lots.

Has anyone costed up producing these machines in bulk?
Based on the costs of materials for the small hobby machines, making a larger scale one to run a Alternator from a car for example could surely be done for $1000 or so.

William, have you built one?

Cheers

C
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Response to Practical Use

Postby stan.hornbaker » Fri Feb 06, 2009 6:13 pm

Craig: There is not a mass market for power producing Stirling engines at a price anyways near being competitive with ICE's. How many times have projects been started in the Mojave Desert, only to run out of R&D funds, have the project canceled and be reinvigorated with new staff (some of old staff in new positions} and new R&D funds?

Scaling up a model Stirling results in an absurdity that simply does not work. Ratio of heat transfer surfaces to volume has a very profound reduction of the heat characteristics of the engine. Like others the answers to your question(s) will be found in prior posts if you will take the time to read and study them.


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Postby Brent » Fri Feb 06, 2009 9:21 pm

Thanks to everyone for their very thoughtful posts. People often ask the same question this way:

Why don't "They" develop a Stirling engine to power my house? My first answer is that there is no "They". There is only you and me, and the other guy down the street.

I don't know why you haven't yet done this and I don't know why the guy down the street hasn't done this, but I do know why I haven't done this and why American Stirling Company hasn't done this.

I haven't done this because every time someone tells me that they want something like this, I always ask them two questions. How much would you be willing to pay for this and what fuel do you want to burn, or what heat source do you want to use?

The prices people have offered me are often lower than we sell some of our models for. Secondly, everyone has a different ideal fuel in mind and the burner or the hot section of the engine has to be designed specifically for one type of heat.

If I had gotten ten people wanting to buy a Stirling engine to power their house and pay say $10,000 USD per house for the product, I would have seriously considered it, IF they had all wanted to use the same heat source.

So that's why this hasn't happened in the past. Let's talk about what realistically could be done with Stirling engines.

1. They should be integrated into wood and pellet stove heating units to move the air and hot water through the house and run fans that would move the heated air through the house.

This is a very realistic add on to a high end wood stove. It needs to be sold as a complete system by a company that is already in the wood stove business. American Stirling hasn't done that because wood stoves are too far from the type of business we have.

This needs to be done by some guy who is already in the wood stove business, who loves technology and who can do at least part of the engineering work to make all this happen with his own talents and his own company.

This is a screaming opportunity for someone who is already in the business of selling wood stoves, it would be a disaster for American Stirling to start this because it's not the kind of customer that we know how to find or service well at all.

Imagine that you had a black box (who really cares what's in it) that would produce all the energy for your house with no further inputs required. If the box was free would you want one? Of course. What if the box was priced at one million dollars would you still want one? (well you might want it but you probably wouldn't buy it.)

The solar guys area always talking about dollars per watt, or how much it costs to buy a certain amount of electric production capacity. This is the right idea, and there are two other things that should be talked about too. How big is the thing you have to buy and in how many places is this thing economically usable.

Solar is great, but it's bulky and expensive and the sun only shines half the day in some places and not at all at some times of year in other places. Wind power, hydro power, and wave power are all only usable where there is wind, flowing water and waves.

The world really doesn't need one more expensive alternative to expensive solar power. The point is how cheaply and how small and how universally usable can you make your alternative energy machine.

"They" are never going to make such a machine, but I don't see any reason why a couple of very smart dB administrators can't dive in and build one for themselves, then build ones for a few friends, then pretty soon they aren't just dB administrators, they are tech savvy energy entrepreneurs.

I'm thinking about writing a book on how to do this? So my question to everyone who reads this post is this?

Would you buy the book? If so, what should the title be?

Brent Van Arsdell
American Stirling Company President

-------------------------------
Brent Van Arsdell
American Stirling Company
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Postby stan.hornbaker » Sat Mar 07, 2009 1:39 pm

There is a new, March 6/7, 2009, discussion of AJOrgan's web site, an editorial from late 2008 on SESUSA Yahoo Forum.
The basic conclusion is that it will require someone innovative enough to acquire some deep insight of Thermodynamics to apply to the design of a really viable Stirling engine.

It is required reading for anyone seriously interested in the subject.
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Postby anthonygonzalez1 » Sat Mar 07, 2009 6:39 pm

Brent, I'm not doubting the tech issues that real engineers have to overcome to make these happen, but you say that the heat source is the issue as far as standardization. I am under the impression that as much as a single degree in temp difference is enough to run one of these. Solar seems like an obvious conjunction of the two. Heat the top by magnification or use solar panels to create just enough juice to power some radiant source of heat to make a temperature difference and were off right? I see these LTD demonstrators all over the web and the only thing I can come up with as far as an issue is scale, but light weight composites on the interior of the machine could do away with much of the weight issues, and as since no heat is produced in the engine itself of measurable consequence(at least that is how it has been explained to me), those parts would not need to be "super-costly" as they do not need to withstand huge temperature changes. The displacement of gas as it heats and cools has to be powerful enough to actually move the piston, I get that, so what else am I missing?

As for DBAs entering the market to create engines, I have an idea, but since no one takes these too seriously, the only people who can seriously be funded for such a project are people like yourselves, engineers who actually build these and have some credentials.

(I have already been advised about reading every thread here prior to commenting, but since it appears comments on my post persist, I am inclined to direct this question again to the experts rather than pouring over virtual reams of discourse by engineers. If will make an attempt to read them though, so that statement is not derogatory, just a factual admittance that I have not the time to read over everything here.)
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Response to Practical Use

Postby stan.hornbaker » Sat Mar 07, 2009 6:52 pm

Anthony G.
Let me respectfully suggest that you take the time to read the post just prior to yours. Lee White and Tom Gentry have had experience with the Stirling industry and their and A.J.Organ's article are quite pertinent to what you appear to be looking for. Note pacificstirling's comment about a new insight into a deep study of Thermodynamics might be the key to making the/Stirling engine viable and/or as ubiquitous as the ICE.
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