World's largest solar installation to use Stirling engine technology

Free Energy News ^ | Aug 05 | Sterling D. Allan

[Arkie2]

ROSEMEAD, CA, USA -- A Stirling engine is commonly referred to as an "external combustion engine" in contrast to the "internal combustion engines" found in most vehicles. Combine a Stirling engine with solar as the source of heat, and you have a highly efficient means of converting solar power into usable energy.

That is what Stirling Energy Systems has been perfecting for the past 20 years.

On Aug. 8, 2005, President Bush toured the DOE's National Solar Thermal Test Facility at the Sandia National Laboratories complex, situated on Kirtland Air Force Base in Albuquerque, N.M., where he signed the energy bill.

Now they are ready to go big-time, with an agreement signed Tuesday with Edison International (NYSE:EIX) a subsidiary of Southern California Edison (SCE), the nation's leading purchaser of renewable energy.

On Tuesday they announced an agreement that could result in construction of a massive, 4,500-acre solar generating station in Southern California. This comes to around seven square miles, with a perimeter of nearly 30 miles. The completed power station would be the world's largest solar facility, capable of producing more electricity than all other currently-operating U.S. solar projects combined.

This signing was a day after President George W. Bush visited their Sandia National Laboratories installation where they have six prototypes in operation, having chosen this location as his backdrop for the signing of the Energy bill.

Signed Tuesday, the 20-year power purchase agreement, which is subject to California Public Utilities Commission approval, calls for development of a 500-megawatt (MW) solar project 70 miles northeast of Los Angeles using innovative Stirling-engine/solar-dish technology. This is enough power to run approximately half a million homes.

According to the California Energy Commission, there are 966 power plants in California that generate more than 0.1 MW. Of those, a 500 MW plant would be in the top 3% for size.

The agreement includes an option to expand the project to 850 MW.

Initially, Stirling would build a one-MW test facility using 40 of the company’s 37-foot-diameter dish assemblies. (Each dish generates 25 kilowatts.) This phase is slated to be completed in the first quarter of 2007. One of the 40-unit arrays capable of a 1 MW output, will be dubbed a "solar power group" and will be the basis of modular calculations for future installations.

Subsequently, the 20,000-dish array is to be constructed near Victorville, California, during a four-year period, starting in early 2008. If Edison opts for the additional 350 MW installation, that will take two more years, and will bring the total number of panels to 34,000.

“At a time of rising fossil-fuel costs and increased concern about greenhouse-gas emissions, the Stirling project would provide enough clean power to serve 278,000 homes for an entire year,” said SCE Chairman John Bryson. “Edison is committed to facilitating development of new, environmentally sensitive, renewable energy technologies to meet the growing demand for electricity here and throughout the U.S.”

“We are especially pleased about the financial benefits of this agreement for our customers and the state,” said Alan Fohrer, SCE chief executive officer. “The contract requires no state subsidy and provides favorable pricing for ratepayers because tests have shown the Stirling dish technology can produce electricity at significantly lower costs than other solar technologies.”

Gil Alexander, spokesperson for Southern California Edison said, "We operate in a competitive marketplace. While [for confidentiality reasons] we cannot give out precise dollar amounts for how much these installations will cost, we believe the final agreement is very beneficial to our customers. We do not need any subsidies to make this work."

Pioneering Stirling-solar to be Commercially Viable

Although Stirling dish technology has been successfully tested for 20 years, the SCE-Stirling project represents its first major application in the commercial electricity-generation field. Experimental models of the Stirling dish technology have undergone more than 26,000 hours of successful solar operation. A six-dish model Stirling power project is currently operating at the Sandia National Laboratories in Albuquerque, New Mexico.

However, this isn't the first commercial application of Stirling engine technology. For instance, Swedish submarines use Stirling engines for propulsion. (ref)

How It Works

The Stirling dish technology converts thermal energy to electricity by using a mirror array to focus the sun’s rays on the receiver end of a Stirling engine. Each panel tracks azimuth and elevation to keep the sun’s rays focused at greatest intensity possible.

The internal side of the receiver then heats hydrogen gas which expands. The pressure created by the expanding gas drives a piston, crankshaft, and drive-shaft assembly much like those found in internal combustion engines but without igniting the gas. The drive shaft turns a small electricity generator. The entire energy-conversion process takes place within a canister the size of an oil barrel. The process requires no water and the engine is emission-free.

Comparison to Other Solar Technologies

Tests conducted by SCE and the Sandia National Laboratories have shown that the Stirling dish technology is almost twice as efficient as other solar technologies. These include parabolic troughs which use the sun’s heat to create steam that drives turbines similar to those found in conventional power plants, and photovoltaic cells which convert sunlight directly into electricity by means of semiconducting materials like those found in computer chips.

Additional Applications

While the number of potential applications for this technology is huge, in the near term Stirling Energy Systems will be keeping their focus on these utility installations.

[Kevin OMalley]

Stirling + solar = read later bump. Should be interesting.

[mugs99]

I'm more interested in the use of the stirling engine here than the solar power aspect. The stirling is just so damn efficient it's a shame it's not used in more applications

Stirling engines are fun to build. They are so simple you can build one from a tin can! I've built several small stirling engines and am thinking of building one to power a generator to replace my gas generator. They are great engines and we should develop them to their full potential.
.

[Arkie2]

Thanks for the link! I put it on my favorites and will check it out later. I have a grandson who would love this.

[Wonder Warthog]

"H2 + O2 probablly releases more energy, ounce for ounce than any C based chain (I'd have to look it up for sure, but that's what I remember.)"

Nope. The carbon-oxygen bonds formed release more energy.

"Which is why NASA uses H2 + O2 in many of their upper stage rockets (minimize weight, maximize energy.)"

Nope again. The reason NASA uses H2 + O2 is to maximize "specific impulse" (i.e. "thrust").

[krb]

I don't think these Stirling engines are designed to fit on top of the roof, are they? I think they are probably big setups that take their own large space.

[sitetest]

Dear krb,

That's a good point. I guess they're kind of heavy and bulky, from the descriptions given so far.


sitetest

[ThePythonicCow]

More thoughts - it is not directly a matter of the weight of the engine, but of the cross section of the cylinder.

The Sterling cannot generate the substained high pressures during the power cycle that the internal combustion engine can with its exploding petro. So it takes a bigger cylinder to get a given amount of torque. All else being equal (such as the quality of the metal used), bigger cylinders weigh more. Sterling engines also need heating and cooling radiators to exchange the heat between the internal gas and the outside sources of hot and cold, and a fly wheel to keep moving. These all add to its weight and size.

Internal combustion engines have another advantage - they provide rapid changes in power output (acceleration !!) by varying the amount of fuel injected on each stroke. To do this with a Sterling, you'd need to convert its nearly constant power output to electricity, store that in capacitors or batteries, and use that to drive electric motors. All this adds up to more weight.

So of these two, if you want the maximum power per pound of engine, use internal combustion. If you want the maximum power per pound of fuel, use Sterling.

If you want the maximum power per combined weight of fuel and engine (a common case for anything mobile) then it depends in good part on how often one can refuel.

• Top fuel dragsters

  

  are refueled every quarter of a mile. They use a huge engine and (I presume) a smallish fuel tank, optimize for power per pound of engine, and even choose a fuel to maximize pressure per square inch in the cylinder. They definitely prefer internal combustion.

• Deep sea military submariners

  

  really really hate to refuel - it can be deadly in times of war. They optimize for power per pound of fuel, and prefer Sterling and lots of fuel, preferably nuclear fuel with its higher power density. Further, since Sterling engines just need a heat difference, not air to produce a particular form of combustion, they are well suited to environs where air is precious. And Sterlings can be very quiet, since they don't require any chemical explosions to work. Boomers like their quiet.

• The Presidents Ford pickup truck:

  

  can easily be refueled every few hundred miles. The engine block probably already weighs about as much as a full tank of gas, so engine weight tends to dominate. And the opportunity for an occassional quick burst of speed is an important feature.

• One might think that hybrid cars, such as the Toyota Prius

  

  could change this tradeoff. They already have the batteries and electric motors, and are targeted more at high fuel economy uses. They could more readily use an engine that produced a steady supply of power, very efficiently. However the size of a Sterling, once you add in the radiators and stuff, is a serious problem for the hybrids, which are already tight on space. According to an analysis at Brad Ideas: Sterling Engine based hybrid car the turbine engine, with its higher power density (and even worse acceleration characteristics), might be a better match for hybrid cars, if anything ever replaces the internal combustion for this use.

• Rockets for heavy space lift

  

  don't need mechanical rotary motion. They need to throw a whole lot of stuff one way, fast and furiously, in order to get somet heavy object to go the other way, fast. It's all about power per pound of fuel for them, and huge thrust per second, from a standing start (literally) in a big hurry.

• Ion rockets used for deep space

  

  need to optimize thrust per pound of fuel, by maximizing the speed at which stuff leaves the backend. Low thrust per second (heck - per hour) is just fine for these guys.

I should warn the gentle reader - I am no professional engine designer. I just made up the above comments by thinking about this subject while taking a nap and doing a little Google searching. I could be wildly off the mark.

[ASOC]

Not a word about all the new jobs this will create as well, mirror polishing, plumbers, magnetic engine tuners, etc, etc.

Actually, this could be a boon to the area, drive from Las Vegas to Searchlight to SoCal - lots of potential power plant area. I did stop by the demo plant last time we went by, cool stuff, would love to have a job there.

Wonder if salt ponds would give a better yield and provide some additional power at nite owing to thermal mass? They seem to work well in the Mideast.

[Arkie2]

Wow. This thread has had a long shelf life and it served its purpose! I've learned a lot about stirling engines and had a lot of fun. Couldn't ask for more than that!

[Anitius Severinus Boethius]

Kamen is working on developing a very small Stirling setup that would be cheap enough for a small third world village to purchase. They could simply use any fuel to burn and local water to produce thier own electricity, and more importantly, distilled drinking water.

As a source of stable electricity for the poorest people in the world, it would be an important step. But as a source of clean water for those same people, it is a giant step.

I hope he can succeed.

[Richard-SIA]

I remember reading about similar uses of Stirling engine technology about twenty years ago. At that time it was thought that we might be able to have individual home units, freeing us from the "power" companies. (yes, that is a double entendre)

As I recall, Kali. found an obscure regulation originally intended to regulate steam boilers, and used it to quash the Sterling generator as being a "high pressure vessel".

The demo unit wound up moldering away at the Stanford's "alternative energy research park".

I guess as long as the power companies keep control of the tech. it is OK to develop, but if it went private it would be regulated out of existence. So much for "free enterprise"!

[Richard-SIA]

No, just microwave. ;-)

Not nearly the problem the eco-nuts made it out to be in order to scuttle it a few years ago.

There are ways to focus the beam, and automatically end the transmission if it wanders off target.

The eco-nuts are not really interested in clean power, they really just want to kill off modern man and tech,, except for themselves and their own use of course!

[Richard-SIA]

I was hoping to see the two "free" piston version.

It ran at 60 cycles a second, and the pistons acted as a generator.

No crankshaft at all, so it made electricity but had no other output.

[FYREDEUS]

GOOD job; Solar power satellites...IF people 'want' to do it.

Which they havent for 30 years.

Gee I thought AMERICANS weren't afraid to 'think big'...or did that end with Apollo? -sigh-

SPACE is the RIGHT place for solar.

[Richard-SIA]

Not as long as the "power" companies and their accomplices in Gov. Org. who depend on you to pay their "energy tax's" have any say on it!

[Richard-SIA]

The "Nevada Test Site" is MILES of secured but nearly abandoned desert landscape.
It is just plain STUPID that it is not being used for ANY kind of solar power generation!

[FYREDEUS]

Not if you use masers...

Of course maybe those might also be 'dual use' adaptable for shooting down incoming North Korean or Chi-Com missiles?

The Neo-Luddite lefties certainly wouldnt want anything useful like that; 'Ronnie Ray-guns' 'Star Wars' missile defence was badddddd science and all doncha know ;-)

[AmericanVictory]

One would hope so. We could use some innovation in energy, particularly in the use of hydrocarbon fuel itself and its production. Wouldn't be a bad trend in nuclear either. We've had relatively decent innovation in wind power, largely by private entrepreneurs in small companies, though some big boys jumped in once the samll guys took the risk, as normally happens.

[FYREDEUS]

A nice idea...but Earth/Luna orbit SPS are only 'uneconomical' to launch because we foolishly [as we've just seen again] buy into National AEROnautical and Space ADMINISTRATION paradigms of WIMPY and expensive ROCKET launchers.

Build Freeman Dyson's "Super Orion" [Daedalus modified to be eco-friendly].

EIGHT MILLION METRIC TONNES [about two orders of magnitude more than everything humanity has heretofore put into space combined] at 35 CENTS/POUND to orbit in 2005 dollars.

Put a CITY into orbit not a 'shuttle'.

Thousands of engineers and spacejacks with everything for initial stage of full space industrialization/colonization; permanent lunar base kit with miners, processors, mass drivers, construction-shack for SPS and Lagrange 4/5 O'Neill colonies with mass catchers, etc...basically the whole package that's been languishing since the Bicentennial...sent up in ONE Orion launch.

Of course we'd have to thumb our noses at neo-Luddite neo-Malthusian antihumans and tear up those silly little partial test ban and UN space treaties that you can be sure the Red Chinese wont let get in their way...but wouldnt it be worth it to advance humanity a century beyond where the lefties will let us be AND give America a REAL 'Project for a New American Century' as well as unlimited energy potential?