Another great idea on ‘solar’ power

23 04 2005

Saw this one over on GizMag

Want cheap, green electricity? The Australians have a simple answer. First, build a 20,000-acre greenhouse to trap and heat air. Then build a colossal tower 1 km (.62 miles) tall in the middle of it. The warm air from the greenhouse will rise through the tower as it would through a chimney, turning turbines and generating enough electricity to power 200,000 Australian homes. It may sound like science fiction, but the project is on track to get approved by the Australian government. If completed, the $800 million solar tower will be the tallest man-made structure in the world.

Time Magazine had it in their 2002 ‘Best Inventions’ category.
$800 million, powers 200,000 Australian homes, and uses up no fuels, and has very little maintenance. AND the greenhouses can be used for other things – all they have to be is hot. I’ll take it!

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6 responses

24 04 2005
Mark Amidon

$4000 per home? Heckuva start-up cost. There will be maintenance, so how long does that start-up take to amortize?
Definitely worth exploring, tho.

24 04 2005
dbs

$4000 per home? Heckuva start-up cost.
I don’t know. What does that compare to, say, a nuclear power plant? Or an oil burning plant? I’d say it’s probably not far off, and the environmental impact from what is essentialy a passive solar mechanism like this thing vs soemthing that has to burn a bazillion barrels of oil or requires buttloads of uranium to run is quite a win – both environmentally and financially.
IMHO, natch. I don’t have all the numbers. 🙂

24 04 2005
sah

Sounds like a kinda cool idea.
20,000 acres covered by a greenhouse? Now that I can’t even comprehend. Would the inside be used? For what? I would think the environmental impact of that would be something to consider…
I like the idea of tapping into the tides/ocean currents for a natural generator.

24 04 2005
dbs

20,000 acres covered by a greenhouse? Now that I can’t even comprehend. Would the inside be used?

Well, here’s how I understand how the thing works. You take about a mile-wide circle of land. It can be anywhere really, it doesn’t matter. Open / sunny / arid would probably be ideal.
You roof it over with glass. You make the roof ‘upside down funnel shaped’ – so there’s a chimney in the middle.
As the sun hits the surface, the area under the glass starts getting warmer than the outside air. It starts rising. Since the roof is funnel shaped, it all gets scooped into the big chimney in the middle. An area a mile across is going to generate some screaming winds in that funnel as the air all compresses together and flies out the top of the funnel.
Put turbines in there, and you have your free power.
They’ve added to this, by putting heatable masses under the glass, like rock or brick a couple yards thick (a method that’s been used in passive solar systems for a while). The rock heats up during the day, and continues radiating through the night, so the turbines keep spinning. They’ll cool off by morning, by late night / early morning are the lowest power consumption times.
Now, think about the environment under the glass. It’ll fluctuate temperature and wind-wise. But not a ton – the outer edges will probably be not quite tropical, but quite warm. As you get closer to the middle, it’ll get windy and much hotter as all the hot wind blows in from the outer spaces.
What would you put there? MOre turbines? On the outer edges, why not plant the entire space with Orange trees? THey’re dark, and like constant warm temperatures. You’d just need to water them.

24 04 2005
Mark Amidon

Extremely expensive and ham-handed estimates for oil-fired electric plants run to $600/KW, which is ostensibly what a “home” uses. Obviously, fuel costs are greater for oil than for this pseudo-passive solar.
As I said: definitely worth exploring. If the higher start-up costs can be amortized without horrific maintenance costs, and if some locality (say, Phoenix) has the acres to spare (outside of town, obviously), then this crazy scheme just may work.
But I shudder to think what it takes to keep a 3000-foot stack chock-full of generating equipment standing.

24 04 2005
sah

Thanks, I had the thing pictured as to how it works.
I think harnessing trapped solar heat is awesome, I love just simple fan vents on a greenhouse
My point is the size/scale of the thing.
My little ranch is almost 1/4 mile along one side and it’s just 40 acres or so.
By my calculations 20,000 acres is a piece of ground 31 miles square; a circle with a mile diameter would be about 500 acres.
I think I’d like to find the impact of covering 31 square miles with glass, as well as the reflective properties.




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