Massive Solar Updraft Towers Planned For Arizona 572
MikeChino writes "Australia-based EnviroMission Ltd recently announced plans to build two solar updraft towers that span hundreds of acres in La Paz County, Arizona. Solar updraft technology sounds promising enough: generate hot air with a giant greenhouse, channel the air into a chimney-like device, and let the warm wind turn a wind turbine to produce energy. The scale of the devices would be staggering — each plant would consist of a 2,400 foot chimney over a greenhouse measuring four square miles. The Southern California Public Power Authority has approved EnviroMission as a provider, although there’s still plenty of work to be done before the $750 million, 200 megawatt project can begin."
I can't help but wonder... (Score:5, Interesting)
these couldn't be built for a small fraction the price by using an atmospheric vortex engine [vortexengine.ca] instead of a tower.
Efficiency (Score:5, Interesting)
Is there some efficiency to be gained by building a four square mile device over, say, 2560 one acre devices? Energy efficiency? Cost? It seems like there's a lot of risk in building one giant unit.
-Peter
dumb question? (Score:3, Interesting)
Why not use the sewers? They're supposed to be enclosed anyway -- they're already pretty hot, and if we built them correctly, we could compress, burn, and expel the gas -- which would maybe produce more energy and utilize existing infrastructure than this idea.
Re:Do a small scale pilot first (Score:5, Interesting)
Re:Efficiency (Score:5, Interesting)
Yes, by the bucketload. Thermal solutions of all kinds scale up - that is twice the size gives you a lot more than twice the energy. One example is that you can have an enormous rotor that works at low wind speeds because there is so much moving air while a small one can't move at all. Another is in large units where you get power from steam several turbines can be used to get a lot more energy out of the steam while in small units you can only spin one.
Photovoltaics don't scale up - double the area and you only get double the power. That's why the nuke lobby liked comparing their 1960s dinosaurs to photovoltaics since eventually there has to be a scale where nearly anything thermal will pull ahead.
Spain Too (Score:3, Interesting)
Spain is doing something similar. But different.
http://www.power-technology.com/projects/Seville-Solar-Tower/ [power-technology.com]
Re:Nuclear Would Use Less Land with Higher Output (Score:5, Interesting)
Because that's how it works. You start with some initial reserves. You mine them cheaply. When you start to run out of reserves, prices go up. The high prices cause exploration. New mines open up, and prices go down. Repeat ad infinitum.
Also, we've actually been using decommisioned nuclear weapons [wikipedia.org] as fuel, which is cheaper than anything else because the uranium there is already mined and enriched.
Regardless, the actual cost of fuel is such a small part of a nuclear power plant's budget that the price could rise twentyfold before you'd notice it at the meter.
It's called enrichment. Besides, if you're willing to use heavy water (which is non-toxic), you can even use natural uranium in a reactor.
The "good stuff" isn't scarce, and the article I linked to provided plenty of numbers that support my position. Why don't you come up with some of your own?
Re:dumb question? (Score:5, Interesting)
Yup, we do this... We generate about 1/2 of our power from the methane off our digesters. (I work for a wastewater plant).
We still burn off a lot of methane - it's not cost effective yet to bring on another generator.
I've been toying with a waste methane coop and buy the extra methane from the WWTP. It would cost about $1/W to buy in, and then you'd be responsible for your share of O&M, and anything extra would be sold back to the grid.
I need about 200 investors at $3K ea. Think of all the green credits you get.
The old nuclear lobby killed itself commercially (Score:3, Interesting)
Don't blame the hippies, they really didn't have the political power you credit them with. The nuclear industry of the 1970s simply showed they were a waste of space and they are still stuck in the 1970s.
Re:The old nuclear lobby killed itself commerciall (Score:3, Interesting)
You still have the "big plant" but made up of a lot of little reactors collectively heating up the steam for very large turbines. A big Chenobyl style steam explosion spreading fuel everywhere or even just water in the radioactive loop can't happen in that situation. A current example is the pebble bed powered plant that should be finished by now in China. However the main problem with Westinghouse etc is that they are more than twenty years behind even South Africa and some good ideas have come up over the last few decades.
Re:Nuclear Would Use Less Land with Higher Output (Score:5, Interesting)
Well, let's see. Coal has an energy density of about 24 megajoules per kilogram, and uranium has a density of 560 megajoules per kilogram. Uranium comes from its ore uraninite, which is UO2 (78% uranium by weight). So let's adjust uranium's energy density to 441 megajoules per kilogram to make up for it.
The density of coal is about 1.05 g/cm^3, while the density of uraninite is 8.725 g/cm^3, that is, uraninite is 8.3 times denser than coal on a weight basis. It also has 18.375 times as much energy.
So, taking into account both the higher density and higher energy density of nuclear fuel, we need 1/(8.3 * 18.375), or 1/152 the infrastructure we need to mine the equivalent amount of coal.
Let me repeat that: for the same amount of energy, we need 153 times as much infrastructure to get it from coal instead of uranium.
Re:Green Energy? (Score:5, Interesting)
Re:Linear thinking (Score:3, Interesting)
Combine both ideas by lining the chimney with photovoltaics
???
Profit!
Los Angeles City Limits (Score:3, Interesting)
A sign bearing the subject line, "Los Angeles City Limits" was stolen from the border of LA and hung by the side of the road in my home town in Bishop, CA some 260 miles away. It stood there several years. It was a political statement of the political reach of the LA Department of Water and Power, which at that time extended to leeching every drop of water our of our formerly verdant vally - an engineering feat that required making water run uphill for several miles. Apparently since then the limit has stretched to Arizona.
To the point of your post: if the LA city limits don't yet extend all the way to DC, I misdoubt they will soon.
Re:Green Energy? (Score:3, Interesting)
Real greenhouses work very differently than atmospheric "greenhouse" gases. An actual greenhouse warms because the glazing stops the convecting hot air, not by absorbing or blocking IR energy. This is easy to prove, all you have to do is build two model greenhouses, make one out of window glass that absorbs IR and make one out of a crystallized salt sheet that transmits IR, after exposure to sunlight both will reach the same temperature.
I read a book about this once (Score:4, Interesting)
It was Glory Road [wikipedia.org]. It was very educational. In it the Galactic Empress' commonest answer to every problem was: do nothing. Almost all problems solve themselves in time, given a wide enough view.
Well worth reading for this and a number of other reasons. It's the best representation of the "stream of consciousness" narrative I've seen, and it's a sexy good story. Actually I have a copy - and no, you can't borrow it. I wouldn't mind seeing what James Cameron could do with it.
You've got to give the Dean credit: whether it was stealing plot elements like the indifference of immortals to the travails of mortals or calculating orbits, the man was not afraid to do his homework.
/ Still hopes Hollywood stays away from Stranger in a Strange Land until I'm dead. I would have to go see it, and what they do to it would be sad.
Re:Green Energy? (Score:5, Interesting)
Construction of a simple tube that tall should be considerably simpler.
It was interesting how, in the artist's conceptual drawings, the whole thing looked slick and clean and modern while in the photograph of the real, working power station, it was rough and industrial-looking. And notice the guy wires supporting the chimney that weren't included in the drawing.
Don't get me wrong, I think this is a pretty cool thing. I just find the somewhat deceitful methods often used by corporations to sell things to the public by not telling the whole truth rather...fascinating. The Sutro Tower [wikipedia.org] (a 700+ foot high TV antenna tower) in San Francisco is a case in point. The original plans called for a rather futuristic single needle. The actual tower as built was a brutally expedient latticework that San Franciscans hate to this day.
Re:I can't help but wonder... (Score:3, Interesting)
"Heating the air within the wall using a temporary heat source such as steam starts the vortex. The heat required to sustain the vortex once established can be the natural heat content of warm humid air or can be provided in cooling towers located outside of the cylindrical wall and upstream of the deflectors."
And where does the energy come from for the steam, or for the cooling tower? Yes you can get mechanical energy from convection, that only happens when there's a temperature differential. Where is the energy to create this temperature differential coming from?
That's the point of the greenhouse in the solar tower -- it traps the solar energy to heat the air and create the differential to create convection currents significant enough to generate useful power. That's where the energy comes from. Where does the energy come from to boil the water or cycle it in the cooling towers? That's the input to the system.
If the design assumes a source of steam, why not use the steam to push a turbine directly? That's how most fuels are turned into electricity.
Oh and the other thing I noticed was missing: the place where this kinetic energy was converted to electrical. That's again why the solar tower's operation is obvious -- the turbine goes in the tower where the highest winds are. I wasn't sure but maybe the design showed the generators in the inlet ducts of the vortex generator? Seems suboptimal. Or maybe it just seems that way because that means the entire vortex represents nothing but waste energy. But all the energy in the water gushing through a hydro plant is also waste so...
Re:Green Energy? (Score:3, Interesting)
Dumping hot air into the upper atmosphere cools the Earth. As air is circulated higher up it more readily radiates energy out into space, bypassing some fraction of the greenhouse gases of the atmosphere.
I'm no atmospheric physycist, but this sounds incredibly compelling, actually. So should we build bigger solar chimneys and send more hot air into the upper atmosphere, generating free electricity while cooling the earth at the same time?
Re:Green Energy? (Score:3, Interesting)
But seriously, this is essentially harvesting energy that's going to waste. Since we're using it to turn turbines and extract energy out of it, technically, it ought to result in a net cooling of the air rather than a heating
Yes, until you consider that they are probably going to do something to that greenhouse to maximise its heat production (such as painting the entire ground area black or somesuch), so it's not going to be the same as an equal area of varied nature.
Re:Green Energy? (Score:3, Interesting)
I'm no atmospheric physycist, but this sounds incredibly compelling, actually. So should we build bigger solar chimneys and send more hot air into the upper atmosphere, generating free electricity while cooling the earth at the same time?
Ever think you could save the world AND get your doomsday mad scientist weapon at the same time? Well here's how.
1. Collect energy from the Earth, either in the form of wind turbines or capturing heat from a system such as this.
2. Use that energy to power a giant laser which you fire off into outer space.
3. The energy of the light which escapes the atmosphere is the amount of energy you have removed from the atmosphere.
Just be careful where you aim it.
Re:I read a book about this once (Score:3, Interesting)