There's a sort of "gee-whiz" article about generating electricity
with solar-powered stirling engines in the August issue of
Discover magazine. The bad news is that the device they're
describing is not a real product (yet), just a research project
funded by a private investor.
The interesting part is that the technology they're describing is not new at all-- the only question is whether they can get the cost down to where they can find a market for it. Their target is 250 watts for $250.
Part of the project was designing a stirling engine that could be manufactured cheaply, and since the "fuel" doesn't cost anything, they were willing to sacrifice some thermal efficiency to get more "watts per dollar". The article says its about half as efficient as the best stirling engines, but *much* cheaper to build. They don't describe it in any detail, though.
For the solar part they're planning to use a 6'x9' array of small mirrors, automatically aimed by stepper motors (and somehow ganged together so they can use fewer steppers). By focusing the light on a small area, they can produce temperatures up to 1200 degrees farenheit. And because the array is relatively flat, they can cover it with glass or plastic to protect it from the weather.
My thought was that even if they miss their cost target, as long as the total price is low some people might buy one just to thumb their noses at the power company. They say a typical house would need between 4 and 8 of these, which would be a $1,000-2,000 investment. You might need demand-priced electricity to make it worthwhile economically (peak sunlight coincides with peak A/C loads).
Their website at <http://www.energyinnovations.com/ describes an earlier version of the product and says it will be on the market next year, but the Discover article sounded like they're now working on a completely different design (with more reflectors, and a rectangular array rather than round). Their web designer really likes the word "revolutionary"...
The basic concept is similar to some government-sponsored research described at <http://www.sandia.gov/ , but on a smaller scale. The Discover article quotes a guy from Sandia saying "In principle, this could work.... I'm going to stay skeptical until I see their data, but if they do pull it off, it could be huge."
BTW the magazine also has a brief article about people who collect sliderules, with photos of some unusual ones.
For some history on solar-powered steam engines, check out a book called "A Golden Thread: 2500 years of solar architecture and technology" by Ken Butti and John Perlin (1980). The first solar engine was demonstrated in 1866, and the first "practical" one was built in Egypt in 1913 (it was abandoned during WWI).
The interesting part is that the technology they're describing is not new at all-- the only question is whether they can get the cost down to where they can find a market for it. Their target is 250 watts for $250.
Part of the project was designing a stirling engine that could be manufactured cheaply, and since the "fuel" doesn't cost anything, they were willing to sacrifice some thermal efficiency to get more "watts per dollar". The article says its about half as efficient as the best stirling engines, but *much* cheaper to build. They don't describe it in any detail, though.
For the solar part they're planning to use a 6'x9' array of small mirrors, automatically aimed by stepper motors (and somehow ganged together so they can use fewer steppers). By focusing the light on a small area, they can produce temperatures up to 1200 degrees farenheit. And because the array is relatively flat, they can cover it with glass or plastic to protect it from the weather.
My thought was that even if they miss their cost target, as long as the total price is low some people might buy one just to thumb their noses at the power company. They say a typical house would need between 4 and 8 of these, which would be a $1,000-2,000 investment. You might need demand-priced electricity to make it worthwhile economically (peak sunlight coincides with peak A/C loads).
Their website at <http://www.energyinnovations.com/ describes an earlier version of the product and says it will be on the market next year, but the Discover article sounded like they're now working on a completely different design (with more reflectors, and a rectangular array rather than round). Their web designer really likes the word "revolutionary"...
The basic concept is similar to some government-sponsored research described at <http://www.sandia.gov/ , but on a smaller scale. The Discover article quotes a guy from Sandia saying "In principle, this could work.... I'm going to stay skeptical until I see their data, but if they do pull it off, it could be huge."
BTW the magazine also has a brief article about people who collect sliderules, with photos of some unusual ones.
For some history on solar-powered steam engines, check out a book called "A Golden Thread: 2500 years of solar architecture and technology" by Ken Butti and John Perlin (1980). The first solar engine was demonstrated in 1866, and the first "practical" one was built in Egypt in 1913 (it was abandoned during WWI).