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Solar + Stirling

I didn't read the Discover article, but this doesn't sound particularly new. NASA has been looking at Stirling engines for solar power plants for quite a while, as well as Brayton cycle engines. A long time ago, Popular Mechanics ran an article on a solar power plant involving a huge mirror array focusing sunlight on a heat collector that eventually ran some sort of heat engine. Again, i haven't read the article, but it seems like this proposal would run into the same sorts of problems that plague all solar electric proposals--the diffuse nature of sunlight, the enormous amounts of land required, the inability to use the land for any other purpose, the problem of steering and cleaning all the collecting surfaces, the dependence of the generator on the weather. Because the collectors are concentrating heat as well as light, a light cloud cover wouldn't totally shut down the array. On the other hand, this might require some sort of cooling array, which might make implementation in a desert more difficult.
 
This is a small rooftop device; I think 250 watt peak max. Their stated goal was to get the W/$ ratio as high as possible to make it practical for home use. There are a lot of rooftops out there.

I know someone who has some photovoltaic arrays; payback time is a couple decades. They would not be anywhere near economically feasible for home use without subsidies and tax incentives.

NASA has some very different design goals if their work was directed toward satellite use.
 
arcticpenguin: I know someone who has some photovoltaic arrays; payback time is a couple decades.
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That could be shortened significantly by quadrupling the price of electricity from the grid. :)
 
This isn't exactly for personal use, and it wouldn't work everywhere, but Australia is planning on building a rather innovative solar-powered generator. It uses a huge (as in multiple square kilometers) green house to generate heat, and a chimney in the middle to suck that heat up a 1 km high tower. Inside the tower are turbines to suck energy out of the wind generated by rising hot air. Pretty neat idea. Gets around the problem of needing large areas without having to rely on expensive materials and lots of moving parts.

http://in.news.yahoo.com/030103/137/1zoxs.html
 
Unfortunately only a small part of the article is posted on the web. I did read the entire article in the magazine however. I thought it was a plausible idea but it didn't seem as unique as the article was making out and it wasn't clear to me why they would be more successful than others before them.

A few other links:
http://travel.howstuffworks.com/stirling-engine.htm/printable
A really nice explanation of stirling engines

http://www.energyinnovations.com/
web site of the company developing the product

One interesting aspect of the story was their use of evolutionary software to develop the product. There was an article about this approach in Scientific American recently. The ability to use the computer to intelligently sift through what otherwise would be an impossibly large set of permutations seems like it might have some significant ramifications for the designs we see in the future.
 
arcticpenguin said:
http://www.discover.com/current_issue/index.html

Discover magazine (August 2003) had an article about a new design for a solar power array. Instead of photovoltaic panels. it has an array of mirrors that focus the sunlight & heat on a Stirling engine.
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With a large enough mirror, and a powerful enough lens, we can gather solar energy and reflect a powerful narrow laser beam right back at the sun!!!

(Intriguing, though my idea has very few if any practical purposes...)
 
davefoc said:

One interesting aspect of the story was their use of evolutionary software to develop the product. There was an article about this approach in Scientific American recently. The ability to use the computer to intelligently sift through what otherwise would be an impossibly large set of permutations seems like it might have some significant ramifications for the designs we see in the future.
Click to expand...
Interesting, but I think the genetic engineering might be a bit oversold. Since it is contained within a computer program, only things that you allow to vary will vary. This will restrict the range of what is considered.

I thought it was interesting that they selected on W/$ instead of pure performance.
 
Ziggurat said:
This isn't exactly for personal use, and it wouldn't work everywhere, but Australia is planning on building a rather innovative solar-powered generator. It uses a huge (as in multiple square kilometers) green house to generate heat, and a chimney in the middle to suck that heat up a 1 km high tower. Inside the tower are turbines to suck energy out of the wind generated by rising hot air. Pretty neat idea. Gets around the problem of needing large areas without having to rely on expensive materials and lots of moving parts.

http://in.news.yahoo.com/030103/137/1zoxs.html
Click to expand...

Cool (or warm, rather). You could prolly grow bananas and marijuana and stuff in the greenhouse too!
 
On the genetic engineering:
AP said:
Interesting, but I think the genetic engineering might be a bit oversold. Since it is contained within a computer program, only things that you allow to vary will vary. This will restrict the range of what is considered.
Click to expand...

Perhaps so, it was still an interesting idea that we are looking at only in the earliest stages of development. It might in the end have more impact than the much hyped artificial intelligence efforts. In the SciAm article they talked about how they had been able to reinvent a number of electrical circuits that had previously received patents. The human inventors of these circuits had required a combination of creativity and good insights into relevant physical laws. It is a bit strange to think of a machine doing something that for humans requires creativity and insight.
 
Ziggurat said:
This isn't exactly for personal use, and it wouldn't work everywhere, but Australia is planning on building a rather innovative solar-powered generator. It uses a huge (as in multiple square kilometers) green house to generate heat, and a chimney in the middle to suck that heat up a 1 km high tower. Inside the tower are turbines to suck energy out of the wind generated by rising hot air. Pretty neat idea. Gets around the problem of needing large areas without having to rely on expensive materials and lots of moving parts.

http://in.news.yahoo.com/030103/137/1zoxs.html
Click to expand...

Hmm. This idea appeared in the Daedalus section of the NEW SCIENTIST quite a while back. Are they also proposing building columns in the desert filled with golden syrup to collect water?
 
arcticpenguin said:

Interesting, but I think the genetic engineering might be a bit oversold. Since it is contained within a computer program, only things that you allow to vary will vary. This will restrict the range of what is considered.

I thought it was interesting that they selected on W/$ instead of pure performance.
Click to expand...

Makes sense, though. My house has plenty of roof area; cheaper, less efficient might be the way to go.

Right now, though, solar power installed seems to be around 4x grid power, and the solar panels seem to be about half the installed cost. So, even if the panels were free, it would still run 2x grid.

I wouldn't put too much credence in these numbers--i bopped around a few sites, and might have misinterpreted what they were saying.
 
teddygrahams said:
Anyone see the Man With the Golden Gun ?
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Yeah, that was about the most misogynistic of all the Bond films (which is saying quite a lot).

I didn't try figuring out the power of the beam; probably less powerful than the diamond laser in Diamonds Are Forever. I didn't see the Halle Berry film, but i expect it was also less powerful than the beam weapon used in that.

I seem to remember them showing the collector grid unfolding; obviously unsuitable for the beam intensity. But they had a floor full of some cryogenic vats, didn't they? So maybe there was another collector array, and the collector being unfolded was just for show (to try to convince would-be buyers that the weapon had some chance of being portable).
 
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