[Starvid]

San Diego Gas & Electric (SDG&E) has contracted to buy 300MW of solar power for 20 years, with the potential to grow to 900 MW within 10 years, from Arizona-based Stirling Energy Systems (SES).

[...]

The contract marks the second major deal recently for SES. In early August, SES announced a contract with Southern California Edison that will result in the development of a 500MW solar project in the Mojave Desert northeast of Los Angeles, with an option to expand the project to 850 MW.

http://www.greencarcongress.com/2005/09 ... gas_e.html

[oiless]

Bunch of useful stirling stuff:
http://www.sunpower.com/technology/public.html

Various stirling stuff:
http://www.flying-pig.org/mechanisms/pa ... rling.html
http://www.geocities.com/Yosemite/Rapid ... plans.html
http://www.stirlingengine.com/
http://solstice.crest.org/renewables/di ... index.html
http://www.bekkoame.ne.jp/~khirata/english/make.htm

I'm pretty sure I have plans for building the dish kicking around somewhere on this machine. I'll look when I have more time.
In any case parabolic dishes are easy to come by. Lots of people are happy just to have someone haul their early eighties defunct satellite dish away for free, stand and all. Diameters are typically 10-12 feet.

[oiless]

Some stuff on laying out a parabolic dish of your choice:
Laying out

Forget stirling, this is the real deal!
http://www.amasci.com/freenrg/minto.html

[Bubbling_Crude]

The SunDish, a solar-thermal Stirling trialled at the Pentagon and later at the Pima Maricopa reservation near Tempe, AZ, was situated at the landfill (in Arizona) in order to make use of landfill methane at night or on cloudy days. The Stirling can be powered by any external combustion fuel, including, as Kamen postulated, camel dung.

And, I'm quite sure that the target market for the units under discussion in this thread does not include the home owner. More likely, it is intended for use in light-industrial parks and office complexes.

[Caoimhan]

The current SES units are rated for 25 kW, which amounts to about 5 homes.

I wonder if a reasonably priced 5 kW unit might be possible. The biggest problem is a serious dearth of reasonably functional stirling engines out there.

I think the design of these CSP Stirling dishes from SES and Solo could be improved, though. The cold side of the stirling engines are sitting out in the sun. If you were to place a second mirror at the focal point of the main dish, and reflect the light back down through a central hole in the dish, the dish itself could shade a large radiator for the heat dissipation from the cold side of the stirling engine. It would also reduce the requirement of having strong struts to support the stirling engine high in the air. Last, it could have the benefit of possibly utilizing a geothermal ground loop attached to the cold side of the engine to provide liquid cooling, which is more efficient than heat dissipation through the air.

[foolcell]

Here’s the idea, combine a Sterling engine with solar heated and geothermal cooled water to generate electricity on a small scale. Some very rough math I get ~ 10 watts per foot with an efficiency of 20%. What do think? Has it been done?

[Caoimhan]

Welcome to the boards. You should have done a search on "solar thermal stirling". You would have come up with some good results.

Stirling Energy Systems (www.stirlingenergy.com) has been researching concentrated solar power with a stirling engine for almost 2 decades now, and get about 30% efficiency. They don't even use geothermal cooling. They just got two big contracts with utilities in Southern California, and will be installing many Megawatts in the coming years.

I, too, think that using a geo-thermal cooling ground loop would be a good idea. If they were to use a secondary mirror at the focal point of the main dish to reflect light back down into the "hole" at the center of the main dish, they could place the stirling engine underneath the main dish, where the cold side of the stirling engine can be at least shaded, or connected with the ground loop for liquid cooling as suggested.

But even as is, their 25kW dish is supposed to come down to $25,000 install price with mass production, making it only $1/watt, which is a great price.

[Bedevere]

The stirling engine is a technology that has been largely forgotten about, which is unfortunate. It will most likely make a comeback as energy prices rise and people in general start to care about efficiency. I am disturbed by the lack of efficiency we have, especially in nuclear power generation and the HUGE amounts of waste heat that are discarded. The heat source is there, and the temperature difference is as well which is everything you need to run a stirling. Not to mention the practice of throwing out nuclear "waste" that still has most of it's nergy content left, but that is a different story.

[foolcell]

Caoimhan thanks for the reply
Yeah, I’ve looked high low but haven’t seen a system that uses solar collectors, the type that’s used in heating portable water combined with a Sterling. What I have in mind is a DIY type system using off the shelf parts. It seems a system like this could be cheaper and extract more energy than a PV set-up.

[Caoimhan]

Maybe it's because you're spelling Stirling wrong?

[Caoimhan]

I understand what you're looking for. I'd love to see a 3kW household system set up with that. There have been some vapor-tech companies out there... but not much else.

There is a company that is doing co-generation of heat and electricity using a stirling engine, but it's powered by natural gas. I'd love to see a CSP do that.

[foolcell]

Thanks for the clarification; I have seen it spelled both ways, stirling and sterling. But Stirling is the correct. CSP Means?

[bentstrider]

Yip.
Stirling is the correct way.
In the late 1700s, this invention was brought up by a reverend named Stirling. A church leader who was concerned of the noise and pollution created by early steam engines.
As was said above, this was a great invention that has been relegated to the shelves for the last 200+ years.

[Caoimhan]

CSP = Concentrated Solar Power

Any device that uses lenses or mirrors to concentrate sunlight to enhance the efficiency of thermal or PV power systems.

[deMolay]

Anybody here up on Stirling Engines? They were invented about 1816 by a Rev. Stirling in England. It could be a far better answer than hydrogen or some of the more hightech solutions. They work, have been around for almost 200 years and are fairly simple. They can be build by people who are trained in machine shop. I have been looking at them for about 10 years and never thought their day would come again, I think this design needs updating and modernizing. What are your thoughts? http://www.stirlingengines.org.uk/pioneers/pion2.html

[Googolplex]

They are a regular subject. You might want to try the search function available at the top of the forums. You'll even find the thread I posted about how a company is going to try using them for a new kind of solar power generation.

[MicroHydro]

They have also been proposed for space probes for more efficient nuclear thermal to electric conversion.

[WhistleWind]

My dad spent a few decades designing stirling engines as
refrigerators for cooling early IR guidance systems in guided
missiles. They are certainly of potential value in a PO world -

They have similar efficiencies to the internal combustion engine.
They are mostly external combustion, so can run on any fuel, eg. coal.
They are a form of heat engine, which means they can run in reverse
and act as a refridgerator.

Given that oil is used for about 90% of transport, any technology that
can be plugged in to a fairly normal vehicle design and run off any
source of external heat has to be useful as a transitional solution.
I don't know about power performance relative to an ICE - my dad
says there were experimental cars in the USA in the 1960s.

They seem like an ideal solution to local electricity generators in a
PO world - run on any fuel.

[Curmudgicus]

There are two applications you might want to check out on the web.

First, at stirlingenergy.com you can read about a company in New Mexico (Stirling Energy Systems) that has a huge array of parabolic reflectors in the desert. Each concentrates sunlight onto a stirling engine mounted at the focal point to generate electricity. Bush did a photo-op there in August. They claim that using their technology "...a solar farm 100 miles by 100 miles could satisfy 100% of the America’s annual electrical needs."

Second, infinia corporation (at infiniacorp.com) makes stirling engines for various applications. They have entered into partnership with ENATEC of the Netherlands and Rinnai corporation of Japan to make home microcogeneration plants using gas fired stirling engines. Each MCG produces 1Kwt of AC for your home, while the heat produced is used in complementary products for home heat, water heaters, clothes dryers, and cooking heat. If you aren't at home it runs your meter backwards, and if your house never uses > 1Kwt you can stay off of the grid. It's going to be mass produced for SE Asia and the NL by 2007-8.

By the way, check out Rinnai's other products like on-demand water heaters and combined Radiant/convective room heaters. Seriously good stuff.

[dbuckley]

Another Stirling powered small scale CHP is the WhisperGen from WhisperTech. Their DC model for marine use has been available for a while, and the home unit threatening for a couple of years.