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THE Solar Tower Thread (merged)

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THE Solar Tower Thread (merged)

Unread postby The_Virginian » Tue 24 Aug 2004, 15:16:21

http://www.enviromission.com.au/index1.htm This company "enviromission" is planing to put a huge tower in Austrailia to provide Solar energy from convection currents!

Now, I know there has got to be some debunking or other criticisims that this company does not tell us about.Is the science behind the figures for power generation realistic? Or is it part dfantasy to attract investors?

Diabolos any comments?
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Unread postby smiley » Tue 24 Aug 2004, 15:31:51

Maybe they have made the same mistake. In the prototype section they state that the prototype generates 50 kw.

The plant operated for seven years between 1982 and 1989, and consistently generated 50kW output of green energy


It is hard to estimate the size of the thing from the picture, but it looks pretty big. I would say that it is at least 100m high with a 50 m radius

If that is the case then I wonder how big the 200 MW monolith must be.
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Unread postby MarkR » Tue 24 Aug 2004, 15:36:28

The science appears to be sound, as there is a prototype of this design, and it does work.

However, some quick back of envelope calculations suggest that the efficiency is pitiful compared to conventional solar techniques - and OMG the size of that thing.

Buried deep within the website, they state that the canopy area is 3,800 hectares. That's *4 miles* in diameter! Then there's the tower thing in the middle - 1000 metres.

Just how do they plan to build that, and how much will it cost?

Is it worth it for an efficiency of 0.4%?
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Unread postby clv101 » Tue 24 Aug 2004, 15:50:21

1km high. The efficiency doesn't really matter when the fuel is free. The only calculations that need to be done are capital costs.

The only other fear is EROEI - concrete is energy expensive, even before you drag is 1000m in the air.

It's a nice idea in theory but many challenges exist - construction, keeping the glass, plastic clean, capital expense...
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Unread postby The_Virginian » Tue 24 Aug 2004, 16:00:00

If you go to the "Company Anouncements, they say they will use 3,800 hectares for green houses, this is out of 10,000 hetre solar tower site.

I assume the inner rings of the glass "heater" would be "too hot", thus only using the outer rings.

Maybe they have made the same mistake. In the prototype section they state that the prototype generates 50 kw


Thanks for the boost amigo. 8)

Is it worth it for an efficiency of 0.4%?


I don't know. Honestly. Seems almost hucksterish to me.

But in the same memo about the purchase of the site, "Enviromission" says they now have a site in Tapio station, Buronga, NSW..the zoning issues still have to be solved.

Maybe this will work where land is real cheap...maybe not even there.
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Unread postby The_Virginian » Tue 24 Aug 2004, 16:02:13

keeping the glass, plastic clean


Good point.

Water is the universal solvent, and in short supply in most parts of Austrailia.
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Unread postby smiley » Tue 24 Aug 2004, 16:13:07

Another thing I don't understand. If you want to capture heat you want to capture radiation right along the spectrum. That means you need to minimise reflection by creating an ideal black body.

I don't know how a silvery shiny thing fits in that concept
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Unread postby clv101 » Tue 24 Aug 2004, 16:20:31

We're not talking about absorbing heat like a black body - this uses the green house effect literally, with food growing inside it (which has the added benefit of making the air damp, heavier and capable of doing more work through the turbines). I think the principles of black body absorption are very different to the green house effect.

The other channange is to keep it going overnight - thing the world largest storage heater to maintain the temperature gradient throughout the night.
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Unread postby The_Virginian » Tue 24 Aug 2004, 16:27:35

As to the construction costs and enginering:

The newly planed "Freedom" Tower in NY will be 1776 ft in hight (counting the Spire) and counting the spire, the tallest building in the world.


http://www.wordiq.com/definition/Freedom_Tower


It will cost 1.5-2 billion USD (and we know how over-runs can be!)

So to biuld a 1 KM Structure in the air must be tremendously expensive

On a side note the "Feeedom" tower will have wind turbines to generate a whopping 20% of the buildings energy needs.

How nice, 20% runs up to the estimate for total practical wind generated elecricity in the US as a renewable recource.
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Unread postby The_Virginian » Tue 24 Aug 2004, 16:31:11

keep it going overnight


(gigle) Yah night.

Why didn't I think of that. No sun = no Heat = no Juice at night.

What would they use as a "heat sink"? Would their even be "excess enrgy" (I doubt it) So these things can help with "peak demand" but they won't keep a city lit at night.
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Unread postby clv101 » Tue 24 Aug 2004, 17:05:16

Regarding efficiency, I think they expect the 1km tower to be 1.5%. The higher the tower the greater the efficiency due to increased pressure difference. They have looked at a storage heater approach to keep the thing going through the night, it's not included in current plans but could help. Anyway – peak temperature power output occurs a few hours after the hottest part of the day, nicely corresponding with peak demand and in the night/early hours, demand is so low that other base load producers will be fine.

700,000 cubic metres of high grade concrete – it's gotta be good, and it's gotta be local materials so a lot of materials testing will be needed.

Total capital costs are estimated at ~US$ 720million. But think of the alternative revenue sources – TEG Heure sundial? Viagra Tower? Tourist attraction to a lofty viewing gallery?

In short it's an interesting project but doesn't really fit in with the scaling down, local idea. Mega projects seldom deliver on promises.
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Unread postby The_Virginian » Tue 24 Aug 2004, 17:41:32

And contrast this with the other famous "mega project the thee gorges Dam"

http://www.cbc.ca/news/features/threego ... facts.html

Here's what happnes when you don't cool the concrete correctly (ice or water pipes as some comments suggest) IT cracks, badly:

http://www.freerepublic.com/focus/f-news/920339/posts

So 1 Km of pure concrete? Up up and away?
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Unread postby MarkR » Tue 24 Aug 2004, 18:20:56

Well, it's cheaper than PV. 8O

But at such a high capital cost, I doubt that it could be remotely cost effective without enormous subsidy.

What about running costs - there's a whole lot of real estate there than will need inspection/cleaning and maintenance.

I wonder what sort of electricity cost they anticipate in the end - I can't imagine any less than US$0.10-0.15/kWh being break-even.
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Unread postby Devil » Wed 25 Aug 2004, 05:07:03

The Oz project, as I heard it, was a 1 km high guyed steel chimney and 27 km2 of greenhouses containing enormous black finned water reservoirs. These served to a) limit the temperature to a tad over 100°C, so that the mechanics of the turbines and the whole caboodle were simplified (for maintenance) and b) ensure sufficient heat storage that it worked 24/7/52.

I'll start a separate thread on 3 Gorges.
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Unread postby Guest » Wed 25 Aug 2004, 06:29:27

The Oz project, as I heard it, was a 1 km high guyed steel chimney and 27 km2 of greenhouses containing enormous black finned water reservoirs.


Saturn,

I went to the web site again under "materials" they wrote the chimney would be made of Reinforced high streangth concrete. And the turbines from lightwhieght Alloy (AL?) "as used in aircraft manufacture."

Steel would be a better option for building up, way up, just like the "Skyscrapers", and TV antenas.

Why use concrete instead of steel?

Does steel release the heat too (conducts) quickly, while concrete has the "thermal mass"/ heat sink ability to make the theorhetical science work?

Problem could come in by actualy trying to build such a thing out of concrete....
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Unread postby Ender » Sat 28 Aug 2004, 05:42:07

smiley wrote: It is hard to estimate the size of the thing from the picture, but it looks pretty big. I would say that it is at least 100m high with a 50 m radius

If that is the case then I wonder how big the 200 MW monolith must be.


It's 1km high. See www.enviromission.com.au.

They are serious about building it, and if it goes well, another half-dozen over the next ten years.
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Unread postby Ender » Sat 28 Aug 2004, 05:45:44

The_Virginian wrote: Why didn't I think of that. No sun = no Heat = no Juice at night.


The Solar Tower will generate 24/7. The air heated during the day will continue to rise through the turbines overnight.

Output will be highest on hot summer days. By happy co-incidence, this is the time of highest demand for electricity, at least in Australia.

I'm convinced this thing has legs.
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THE Solar Tower Thread (merged)

Unread postby Antimatter » Fri 25 Feb 2005, 08:36:42

http://www.wired.com/news/technology/0,1282,66694-2,00.html?tw=wn_story_page_next1
The quest for a new form of green energy has taken a significant step with the purchase of a 25,000-acre sheep farm in the Australian outback. The huge alternative energy project isn't driven by manure, but by a 1-kilometer-high thermal power station called the Solar Tower.

Announced several years ago, the 3,280-foot Solar Tower is one of the most ambitious alternative energy projects on the planet: a renewable energy plant that pumps out the same power as a small reactor but is totally safe. If built, it will be nearly double the height of the world's tallest structure, the CN Tower in Canada.

The Solar Tower is hollow in the middle like a chimney. At its base is a solar collector -- a 25,000-acre, transparent circular skirt. The air under the collector is heated by the sun and funneled up the chimney by convection -- hot air rises. As it rises, the air accelerates to 35 mph, driving 32 wind turbines inside the tower, which generate electricity much like conventional wind farms.

But the Solar Tower has a major advantage over wind farms and solar generators: It can operate with no wind, and 24 hours a day. Thanks to banks of solar cells, the tower stores heat during the day, allowing it to produce electricity continuously.


This seems to be the first solar technology that makes decent power, 200mw is nothing to sneeze at! Im guessing that it wouldn't have to be backed up with spinning reserves like pv and wind due to the large thermal mass of all that air. I dug up an older article with some more infomation: http://tinyurl.com/6ow84

EnviroMission and SBP estimate the cost of their first 200-megawatt solar thermal tower at $670m, and say the cost of subsequent towers would fall. An engineering infrastructure, materials manufacturing plants and trained workforce would be in place and the design and construction would have been refined.

The initial cost is comparable with the $600m cost of building a new 200MW brown-coal power station and a drying plant for the coal, which is nearly 70% water by weight. A 200MW black-coal power station in Queensland would cost $440m. Davey says these prices ignore the unknown environmental and health costs of greenhouse gas, sulphur and particulate emissions from coal-fired power stations.
The greenhouse gas emissions gen-erated in the building phase would be recouped within the first two-and-a-half years of operation, says Davey. Thereafter, it’s a free lunch: zero emissions, convertible to carbon credits in a global market.

Follows that energy paypack time should be roughly 2.5 years. Not too shabby!
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Unread postby nocar » Fri 25 Feb 2005, 09:22:07

I do not understand how it is supposed to yield pour 24 hrs a day when it is solar powered. Can someone please explain?
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Unread postby nocar » Fri 25 Feb 2005, 09:23:11

I meant power of course.
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