New Solar Wind Downdraft Tower Could Revolutionize Wind Power Technology

This isn't exactly new. I've seen this concept years ago, with additional shrouding at the base of the tower to help distribute the moist air over cultivated areas right nearby as the long term effect causes a cooling of the soil in the immediate vicinity.

Is it better than this idea:

http://inhabitat.com/enviromission-plans-massive-solar-updraft-towers-for-arizona/

After reading the information on their website (they were formally Clean Wind Energy Tower Inc) does anyone else think something's......not quite right?

http://www.solarwindenergytower.com/the-tower.html

The provided math. 1,250 MWh for a single site is given but not much else. I found some info on their previous (similar) design giving a theoretical potential hourly yield of 700 MWh minus approximately 17% for water pumping operations (etc), yielding approximately 600 MWh per tower.

Claims it is the first hybrid solar-wind renewable energy technology in the market (when it isn't in my opinion).

Comments such as "Uses benevolent non-toxic natural elements to generate electricity", where the elements are pumped water naturally heated to create wind.

:|

Hmmmmmm. What does anyone else think (after looking at the info available on the website of course)?

The goofy way they use units bodes ill. I bet their decimal points are just as goofy.

The expected power generated did look too high, although I couldn't find any info on how large the tower would be.

Placing in a hot desert for maximum efficiency is great, but this thing needs a large continuous supply of water, a great deal if not most of which is effectively lost due to evaporation. That's a rather large problem that standard wind turbines don't have.

I would like to see a cost and performance analysis against existing wind turbines and hybrid alternatives, I don't see this design stacking up at first glance.

:(

I don't claim to be an expert of any sort on this, but the design just plain looks wrong (when I think about it):

1. One would think it would be better with a tower that converges- maybe like a trumpet set on the mouthpiece, with external bracing. This would tend to accelerate the air as it descended, allowing for kinetic recovery instead of it slowing as the tower flares out near the base.
2. This would also let the designer use higher speed turbines, which I understand (correct me if I'm wrong) tend to be more efficient at power recovery than typical wind mills,
3. I would also expect to see a lot less turbines than pictured- it seems to me there would not be a lot of flow through each one as shown, unless they are not to scale in the pictures.

Lots of higher speed wind turbines sounds like a good idea running at the proposed 50 MPH speed this tower is supposed to generate, but that's a lot of air flow for what effectively is a solar updraft tower design operating in reverse!

The idea does not seem well founded. The website does not instill me with confidence that any type of legitimate rigorous analysis validating the idea has been completed.

Even if enough energy can be generated from the air made more dense by cooling to offset the what is required by the pumps and the reclaim system, the result will be air around the tower will become more humid and slightly cooler, which will decrease the ability to cool the incoming air.

....unless of course you have a steady wind, blowing in new dry warm air.....but if it requires a steady wind anyway, why not just put up a wind turbine?

I agree that this just seems wrong but I cannot point to a specific flaw in concept. What keeps bugging me is the concept of making the air more dense by evaporation of water. Evaporation will cool the air but the barometric pressure drops when the humidity climbs. Storms are low pressure centers.

Wait a minute, they claim that the water vapor gets reclaimed for reuse. How much energy does that take?

Barometric pressure (a reflection of density) increases as air takes up moisture at a constant temperature- even more so as it is cooled by evaporating the water first. I don't have a clue how they reclaim the water vapour though!

Could you explain or cite how air density increases with humidity? As this article points out, the density of humid air has been observed for almost 300 years. I like the section where they tie in Amadeo Avogadro's early 1800's work.

My bad, you're right- not only did I forget O2 & N2 vs H20, I calculated it as mw 46 (CO2!!!) .

^{Think I'll go back to school and start posting homework questions on CR4}....

17% apparently, including pumping the water up the tower, so up to 119KWh.

This won't work....heat rises, the tower in the sun is heated, causing an updraft...Misting the air will just blow misty air out the top...In order for it to work it would have to be huge and use too much water, the pumps would probably require more power than the turbines produced...

"the pumps would probably require more power than the turbines produced..."

Exactly what I was thinking, "How can this thing generate more energy than just pumping the water uphill to run a water wheel?

I detect the familiar odor of Snake Oil here.

The only proffered energy source in this charade is the [solar] heat of the desert that vaporizes the atomized water. How does the water get to the desert anyway? Isn't that an oxymoron in itself.

Bogus!

How does the water get to the desert anyway?

They are not surprisingly quiet on this and the efficiency of any water reclaiming features. If it were an efficient system surely they would market it as a feature, such as "large storage tank of water required but only small losses so standard tap pressure water supply needed".

The thing is dead in the water if you have to have a fleet of water tanker trucks constantly moving back and forth to a remote desert location.

The more I think about it the more it looks like an investment scam. These guys have been around long enough to know about these serious and apparently unaddressed design problems.

:|

Isn't that an oxymoron in itself.

Actually it's not. The reason is that the water is not on the surface of the desert, but is below.

So the difficulty is not that there is no water in the desert, it's pulling the water up from underground to the top of the tower.

Here are a few links that might be of interests (Mojave and Sahara)

Wouldn't it be simpler to add the ring of turbines at the bottom to the cooling towers already used on both coal and nuclear plants?

I didn't analyze the proposal, but it sounds a bit like perpetual motion. As others have pointed out, where does the water come from in a hot dry climate?

"... to add the ring of turbines at the bottom to the cooling towers already used on both coal and nuclear plants?"

That would impact on the ability of the towers to do their job (cooling), and so reduce the efficiency of the thermal generation. Also, the air flow in conventional cooling towers is upwards.

Yes, I know the air flow is up which would mean you would be extracting energy from the input air. And I did think that extracting energy at the inlet would decrease the efficiency of the cooling tower, but didn't say anything. I suspect his down-flow "chimney" will not function with enough power to be able to extract energy (and maybe won't work at all, but I haven't studied that.)

I am missing something, or all the data is. I read two articles on this and did not see the energy loss for the pumps to raise the water either explained or accounted for. Is this capable of generating more out then what is put in? You raise water against gravity, you let it fall by gravity - equal energy. You gain some from the cooling effect. You lose water to evaporation so you expend energy to replenish the supply. I still don't see this being better than letting free energy (the wind)turn the blades, other than a bit more aesthetic to some folks. Now when they do use the wind as well, then they do gain some "free" energy. I guess for a hot, dry, windless climate, this is definitely better than a coal fired generator station, assuming the actual energy gains are a bit greater than it would appear. Now if your water source was a lake or stream above the top of the generating tower.....

Reply to #2

This looks like a pump and dump penny stock company....big plans, exciting announcements, but nothing actually works as advertised....and it has a peswiki listing....

http://peswiki.com/index.php/Directory:Solar_Tower

http://www.enviromission.com.au/irm/content/default.aspx

This was claimed pilot project....

http://www.solar-updraft-tower.com/en/technical_concept/prototype_manzanares

This company looks similar....found their patent app...

http://www.google.com/patents/US20120274068

...???...

http://www.google.com/patents/US20120261918

So what happened here....?

http://cleantechnica.com/2012/03/25/clean-wind-energy-tower-shares-plunge-as-downdraft-tower-construction-plans-proceed/

Anytime I see the words "could revolutionize" in the headline, that means there are some serious technical and/or practical hurdles that have to be overcome, and it usually involves violating the laws of conservation of energy or spending more money than can be made over multiple lifetimes of the equipment never mind the cost of money.

Coming out of my state of Martyland makes it immediately suspect.