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.
he was also developing this really cool device for 3rd world nations that would incorporate a sterling into a thing that would purify water and generate power enought to power a small well pump. You could run it on any fuel, alcohol, cow dung, sticks.....
The place that the internal combustion engine beats the Sterling is in horsepower per pound. The place that the Sterling beats the internal combustion is in efficiency.
In other words, the Sterling can get more horsepower out of a given amount of fuel, but it takes a bigger engine to do it.
There is a simple reason for this difference. The internal combustion uses the explosion of fuel, right at the point that the cylinder is starting to go back down, to maximize the heating (and expansion) of the gases. Normally, when you expand gases, they cool, which works against the heating you want to get the gas to continue to expand the combustion chamber rapidly on the power stroke. The internal combustion engine uses exploding petro to keep the expanding gases hot. This gets more power per pound of engine, but is less efficient.
The Sterling engine uses no chemical explosions. It is an efficient mechanism to convert any available temperature difference into a mechanical rotary motion. It is very useful on submarines, where you have hot nuclear fuel (or steam derived therefrom) on one side, and cold ocean on the other side. It is very useful on the solar project described in this post, where you've got heat from concentrated solar rays on one side, and the relative cool of ambient air on the other side. In these example applications, the increased weight penalty per horsepower of the engine is not a significant problem.
The Sterling engine moves a closed gas between the hot side and the cool side. When on the cool side, the gas contracts pulling a piston one way. When on the hot side, the gas expands, pushing a piston the other way. A flywheel is necessary to keep the action moving, from one stage to the next.
Not one acre for ANWR drilling but 4500 acres for some sun depriving monster in the California desert. Where are the eco freaks who speak for the poor desert wildlife being deprived of their homes.
For the Sterling engine, the second cylinder is just going along for the ride, to help move the gases between the hot and cold sides of the main cylinder at the right time. That second cylinder is producing no power on its own. It must be 90 degrees off the primary cylinder, because that is what is needed to move the gases at the right time. Since it is not producing any power on its own, its phase makes no difference to how smooth the power is.
Dear PythonicCow,
Thanks for a very lucid explanation.
sitetest
The efficiency gap is closing quickly, new materials, composite, techniques, use of solar power, etc... This article states they are are getting 45 Kilowatts of power from an engine that will fit inside of a 55 barrel drum.
This power is generated everytime the sun shines without any fuel source, how can you complain? I often wonder how many advancements would have been made if the research and development of this engine was spread out over those 111 years.
You're welcome.
Is 25 KW enough to power a single home? Could one just have one of these things at their own home?
Dear krb,
Twenty-five kilowatts is enough to power my house (fairly new, pretty big, pretty good number of gadgets, electric heat pump) as long as I don't turn everything on all at once. ;-)
I was looking into a whole-house standby generator at around 15KW, propane or natural gas-powered. With 15KW, I could turn on most of my stuff, but I'd have to be a little careful. With 25KW, I could pretty much turn on everything in the house and leave it all on, it's just the peak requirements if I flipped all the switches all at once.
That being said, I'm not sure where I live I'd get 25KW from a dish this size even on a sunny summer day - just too far north. And at night and on cloudy days...
Still, if the price were right, it'd put a big dent in my electrical bill.
sitetest
We used to set one 25 KVA pot/5 houses. LOL. I'm old...
Acres and acres of arid scrubland along I-40 in New Mexico alone. Millions more, no doubt, in California and Nevada (I saw some of it last month). There's miles of flat sand with only I-15 and a railroad track going through it, adjacent to Primm, NV. There are also the Bonneville Salt Flats in UT. We have tons of room for solar, wind, and any other renewable energy source.
I can't wait for the greens to start their objections though. Surely there's some toad or lizard that will be affected by all those solar power arrays.
As far as the greenies are concerned, tell them to deal with it, or move to Europe. Put the endangered species in a frickin' zoo, baby!
I bet with a 25KW stirling solar generator and a good demand control unit in your house you could do it...
Dear patton,
"LOL. I'm old..."
Yeah, me too. ;-)
Our first house had been UPGRADED from, I think, a 60-amp fusebox to a 100-amp fuse box. My current house has TWO circuit breaker boxes. I'm not expert at this stuff, but it seems that each is 400 amps??
Wow.
sitetest
Dear krb,
You're probably right!
I have enough roof area, between the house and the detached garage, and the sheds, for six or eight of these things. I could produce 100KW or more, and store what I don't use during daylight hours in batteries.
I could convert one of the sheds to store the batteries required, and we'd be a net PRODUCER of energy. BGE (local utility) would send ME monthly checks!
Now, all I need is the six figures (or however much it would cost) to buy it all and get it installed. Anyone wanna give me a grant?? LOL.
sitetest
I grew up in a time of dozens of migrant workers in the fields to harvast corn, cotton, and other row crops. Now I sit on my deck and watch as two people harvest a field in 1/10th the time it used to take dozens.
I grew up in a time of dozens of migrant workers in the fields to harvast corn, cotton, and other row crops. Now I sit on my deck and watch as two people harvest a field in 1/10th the time it used to take dozens.
They will be along shortly. Trust me.
Sometimes that happens even if you hit refresh. I always assume it's been posted. ;^)
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.