Massive Solar Updraft Towers Planned For Arizona

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."

Comments

I can't help but wonder...

[Rei]

these couldn't be built for a small fraction the price by using an atmospheric vortex engine instead of a tower.

Efficiency

[pete-classic]

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

Re:Efficiency

[dbIII]

Is there some efficiency to be gained by building a four square mile device over, say, 2560 one acre devices?

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.

Re:Do a small scale pilot first

[Locke2005]

Coal plants make up the vast majority of the power plants in the US and are definitely the most environmentally damaging form of energy production on the planet. Fixed that for you. Coal plant emit more radioactive material (radon) than nuclear plants, in addition to sulphur, other pollutants, and carbon dioxide. Some of this could be cleaned up through better smokestack scrubbers, but from an environmental impact standpoint coal is definitely the most expensive energy source.

Re:Nuclear Would Use Less Land with Higher Output

[QuoteMstr]

So tell me then, why did the price of Uranium go up?

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 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.

the good stuff is scarce

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?

[cptdondo]

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.

Re:Nuclear Would Use Less Land with Higher Output

[QuoteMstr]

How big are uranium mines, the roads used to transport the uranium, the refining plants, the reprocessing plants, and the mountain that is needed to store the waste for several millenia?

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?

[SEWilco]

2400 feet is not high in the atmosphere. 2400 feet is similar to the height of the newly created world's tallest building, so construction obviously will be somewhat challenging. But in the scale of the atmosphere, 24,000 or 48,000 feet would be more impressive. But even those are routine for thunderstorm convection, so are hardly unusual.

Re:Green Energy?

[gyrogeerloose]

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 (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.