Posted on 08/13/2005 3:42:35 AM PDT by 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.
Solar bump!
At a kilowatt each, as soon as someone turns on the air conditioner or irons some clothes...
Stirling engine, an external combustion reciprocating engine having an enclosed working fluid that is alternately compressed and expanded to operate a piston, thus converting heat from a variety of sources into mechanical energy. A Stirling engine can use any type of fuel as well as solar energy and heat from the waters of a hot spring. The engine was invented in 1816 by a Scottish minister, Robert Stirling, before the gasoline and diesel engines appeared. Stirling engines are unique heat engines because their theoretical efficiency is nearly equal to their theoretical maximum efficiency, known as the Carnot cycle efficiency.
Bump for later... I love Stirling engine stories.
The same comment applies to any type power plant of course. What's interesting here is that someone is using the stirling engine for power production. It's far superior to the internal combustion engine in terms of efficiency but hasn't seen many modern applications outside of some very limited uses such as in submarines.
Bump
self-ping
This is the last unexploited technology available for use. Conservation and nuclear is the only way left to cut fossil energy use further. After the Sterling car engine no "three times more efficient" technology is within sight.
Satellite solar power, if people want to do it. Big job.
Nuke-a-bird technology?
37' diameter dish is almost exactly 100 m^2 in area. At roughly 1KW peak solar power/m^2, the conversion efficiency is about 25%. Pretty good for solar. Calling this a 500MW generator is a little dishonest though IMHO. Power is what matters. 500MW at what rate, and for how long? I could strap a drill motor to a bicycle and call myself a 500MW generator. It wouold probably take me a lifetime to do it though.
I think they could market this better as peak shaving power for industry. Maybe even get some corporate investment, rather than saddling residential consumers with the cost. How much solar power is available during the residintial use peak of say 6:00pm to 11:00 pm? Ans. not much.
Stirling is interesting because it's efficient and versatile. Any source of heat can be used: solar, fossil fuel, wood, etc. I think they're used in submarines in some capacity. IIRC there are some technical challenges with durability. Something aout maintaining a seal across the working piston with a large delta T across it maybe,
My knowledge of thermo is a little rough, but I would bet that massing a large number of reflectors of a collector, and then utilizing steam power would be more efficient.
Perhaps $60+/bbl oil will bring a new surge in American innovation.
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.
I am for any generation that will generate during the peak hours. Here in Texas with the wind generation the wind blowing at night during the off peak hours, I am up to my chin with excess generation and know where to put it.
I believe the article specifically mentioned that the stirling is more efficient than steam and the article also mentioned better efficiency than solar arrays which converted heat to steam for power production.
Interesting potential. Isn't capitalism and America grand? Give us $66/barrel crude oil and we'll devise a way to do it better and, most importantly, cheaper!
Good post. Needs some pics and illustrations though. They can be seen here >http://www.sandia.gov/news-center/news-releases/2004/renew-energy-batt/Stirling.html
So, if the Stirling engine was invented in 1816, then why did it take 211 (!) years for somebody to realize the economic viability of the thing?
New means of electrical generation aren't going to have a direct impact on oil use though. Most electricity is derived from coal, nuclear, or natural gas. I mean if we could generate enough electricity to make electric vehicles practical, that would be an offset, but right now they're a solution in search of a problem. A means of distributed power generation might make it practical, but as always, fuel is needed.
If somebody married a Stirling engine to a hybrid vehicle, THAT would be interesting.
Are you in the energy field?
I think it's closer to 189 years. When it gets up to 200 we'll start realizing its viability.
ping
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.