quote: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 20 years.
Now they are ready to go big-time, with an agreement signed Tuesday with Edison International (NYSE:EIX) subsidiary 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. The completed power station would be the world's largest solar facility, capable of producing more electricity than all other U.S. solar projects combined.
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 dish technology. 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. Subsequently, a 20,000-dish array would be constructed near Victorville, Calif., during a four-year period.
“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.”
Sounds like very good news. Quick question though: later in the article, it says that 13,000 gigawatt-hours is enought to power 2 millon homes for a year.
If I did the math right, this means one home requires 6.5 gigawatt-hours per year. That can't be right, can it? Wouldn't that imply a constant load of 6.5 gigawatts constantly, all year round?
What am I missing here?
Posts: 26071 | Registered: Oct 2003
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posted
This is good news. I especially like the bit about one plant producing more electricity than all the other solar plants in the US combined. Does anyone know this station stacks up to a typical coal, oil, or nuclear plant? In terms of energy production or number of homes provided for, I mean.
posted
Looks like good news. Photovoltaic technology has been steadily improving over the last decade. Single cells the size of a dollar bill these days can collect and harness more solar energy for conversion than entire solar panels could a couple decades ago.
It won't be long until solar is able to compete with other forms of energy, once the benefits are weighed.
Posts: 21898 | Registered: Nov 2004
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This isn't photovoltaic, it's a striling engine that drives a generator.
So it goes heat => kinetic energy => electricity.
It's easier and cleaner to produce the needed equipment, but I don't know if photovoltaic's theoretical best is better than this method's theoretical best.
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Photovoltaics are now and have always been limited by very poor efficiency. The problem is the semiconductor material the solar cells are made from. Their chemical composition limits them in such a way that their efficiency approaches about 25%. All the improvements in solar cells, since day one, have been improvements in storage and optics. Until they find or invent a new element that can more effectively convert light to energy, solar cells will remain inefficient.
Of course, the other option is to drastically reduce your power consumption on the demand end, therefore reducing the amount of solar cells needed. This is what they do with most of the solar powered houses. Efficient gas appliances, compact fluorescent lights, stuff like that.
Posts: 5462 | Registered: Apr 2005
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Isn't it also far more efficient to use the sun for lighting directly? I read about a system that captures sunlight and sends it through the house in "tunnels." A sensor determines how much light is present and uses a light bulb to make up the difference. The fixtures let this light out where desired. As little electricity as possible is used to create light, and the light is more natural.
Sounds cool, although of course the collector will have to determine whether to route light to the photovoltaics or to the lighting fixtures.
I've also read something recently about nanotechnology being used to increase the surface area, which increases the amount of material being stimulted by the light. It's still limited by the theoretical maximum eficiency, but it lets far more of the light get used.
Pretty cool stuff. I'd love to build a solar house someday, maybe also a home windmill if I ever get a very big lot. Posts: 26071 | Registered: Oct 2003
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I wonder if there's a way to use a small one of these to generate electricity for a vehicle? or just flat power one...
Posts: 3846 | Registered: Apr 2004
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The wikipedia article on stirling engines says that the main problem is weight - you need very good heat exchangers. It's a good read.
The cool thing is that they are powered by temperature gradients. Someone posted something a while back about energy from ocean water from below the thermocline. It's just above freezing, so it could be used to increase the temperature gradient.
Posts: 26071 | Registered: Oct 2003
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Vehicles are a whole 'nother story, because as Dag mentioned, weight is a big problem, as is power. It would take a ridiculously large solar collector to produce sufficient torque to even get a Geo rolling.
I've never heard of rerouting the light through the house, that sounds cool. I'm gonna research that today (Lighting design is one of my main job responsibilities). I'm also gonna look for the thing about nanotechnology with solar cells.
The last advance I read about was basically turning the glass plate on top of the solar cell into a prism, so that no matter what angle the light hit it at, it would still redirect and hit the semiconductor material at 90 degrees.
This just made the output more consistent, and makes installation a lot simpler (since the panels don't need to track the sun's movement so closely).
Posts: 5462 | Registered: Apr 2005
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quote:In addition to being able to manufacture photovoltaic cells more quickly through printing, the companies also say that manipulating materials 100,000 times smaller than the width of a human hair will provide more light- collecting capabilities.
Each printed nanostructure solar cell would act as an autonomous solar collector, and sheets of these products would have more surface area to gather light than conventional photovoltaic cells.
quote:Their 4-foot-diameter solar dish will light 1000 square feet inside -- minus the harmful UV rays -- rendering a more natural lighting feel, which can be hybridized with florescent and possibly LED lighting to provide a constant light level, though the tone changes with the level of light outside. The GPS-based sun-tracking mechanism uses very little energy.
posted
Fascinating. I much prefer this to photovoltaics, which last I read still couldn't be produced or disposed of cleanly (heavy metals and other toxins involved).
Posts: 10886 | Registered: Feb 2000
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That's bloody brilliant! I just did a bit of research on Stirlingengine.com
50% of Carnot efficiency is pretty insane.
For a car, I was picturing a small generator on top, turning constantly to track the sun... but that might be awfully tricky.
It says you need about 500 degrees temperature difference to make it really powerful... you should be able to achieve that with a solar oven... so these guys in Cali are definitely on to something...
and the whole engine has about 3 moving parts...
I'm way excited about this and seriously going to try to build one from scratch...
edit: that is build a simple Stirling Engine out of a solar grill and some teapots or something... not a solar powered car based on the same.
Posts: 3846 | Registered: Apr 2004
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quote: that is build a simple Stirling Engine out of a solar grill and some teapots or something... not a solar powered car based on the same.
And I was about to be seriously impressed.
One thing I like about the stirling idea is that someone could build one on their own. It's a level of technology that could be maintained by a competent person with reasonable mechanics tools.
Photovoltaics can't do that. One thing I like about solar (and wind) power is the ability to be more self reliant. It's the parnoid individualist in me.
Posts: 26071 | Registered: Oct 2003
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Yeah, that solar nanotechnology stuff is interesting.
Reminds me of the solar powered cellphone charger I built last year. It cost like 20 bucks to make, and the solar cell was about 16 bucks of it.
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Maintained? heh... it looks like it could be maintained for decades with an oil can and a rag. Posts: 3846 | Registered: Apr 2004
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Exactly. And fixed if it broke by a moderately skilled mechanic (maybe a machinist).
But if a photovoltaic cell goes? You're done.
Plus, they are working on a version that produces rotary motion directly, although for now it's still more efficient to convert the linear motion to rotary.
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