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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."
This thing does not ADD any energy to the atmosphere. It EXTRACTS energy from it.
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If you think big enough, you'll never have to do it.
This DOES (essentially) reduce thermal energy in the atmosphere.
:)
Typically, the solar energy just heats up the ground, and also bounces around in the atmosphere and heats it up. This thing works by trapping the energy in a small area (greenhouse) and then using some of that heat to generate electricity. By the time the air is pumped out into the open atmosphere, it has less heat energy than if the thing wasn't there to begin with.
This really boils down to being just like a photovoltaic panel. Rather than the Sun wasting its energy heating up the atmosphere, we use the energy to make electricity... which we then waste by turning electricity back into heat which heats up the atmosphere.
-Bill
Back in the 70s there was a proposal to build a very tall cylinder (1 mile or so), inject water mist at the top, and let the resulting downdraft drive a turbine a ground level. Interesting idea, fairly well developed and into the engineering stage. Of course, nobody funded actually building one. The engineer who designed it couldn't overcome the skeptics, and nobody thought it would be competitive with cheap natural gas/oil-fired generators.....
What precisely do you think they're trying to do? Where do you think this thermal difference comes from exactly? Every single process that generates usable electrical power generates thermal energy. Simple thermodynamics dictates that a process must be less than 100% efficient and must create more disorder than order. So instead of converting coal and air into CO2, electrical power and heat; we're converting solar thermal energy into electrical power and waste heat. The thermal energy is already there and is going to waste otherwise.
Sigs are too short to say anything truly profound so read the above post instead.
It doesn't generate a shitload of radioactive waste, perhaps?
Someone failed physics, but applied for a patent anyway.
If you go to the front page of that site it goes on about the "stored energy resources" of the "latent heat of water vapor in the bottom kilometer of the atmosphere", is just so much nonsense. The wikipedia article just regurgitates the patent application.
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Most of the nuclear waste in the US is recyclable. The amount of waste produced for a given amount of power is small compared to coal, pil and other fossil fuels. Thorium reactors produce even less waste than Uranium/Plutonium reactors do and is more common as well. There is also the problem of low carnot efficiency of solar updraft towers relative to other solar thermal designs because of the relatively small thermal gradient. The larger the thermal gradient, the higher the efficiency.
Sigs are too short to say anything truly profound so read the above post instead.
I call bullshit. If environmental activists...
There isn't any "if" involved here. Feinstein is sprinkling "national monuments" all over the Mojave to prevent solar projects.
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No development of any kind, anywhere, under any circumstances, ever.
EnviroMission has been failing in Australia for at least half a decade. They aren't going to get anywhere in the US.
Lurking at the bottom of the gravity well, getting old
If built, the towers would be the second (and third) tallest structure on earth, behind the Burj Khalifa that opened this week.
Many, if not most wastewater (sewage) treatment plants in the US produce a net energy surplus, which is then returned to the grid.
There's a huge amount of nuclear fuel available. Nuclear fuel supply is not a problem.
You are completely wrong. At some point there will be a scale where the chimney will pull ahead.
Double the area of photovoltaics and you only get twice the energy. As turbines get larger the losses are proportionally smaller, and when you have more moving air you can have more blades optimised for different speeds. It's a comparison of a rising curve for the chimney vs a line for the photovoltaics. After the point where they cross the chimney gives you more energy for the area.
The problem with building a 10% scale device is that you can't find as many excuses for not actually, you know, building one. This project is intended to extract money from investors and governments, not extract energy. When the first one you want to build is ridiculously big, you really don't intend to build any.
For instance, in this solar thermal plant they built the first few to prove the concept. Makes perfect sense if you're actually intending to generate power.
You vastly underestimate them. In addition to their US and Australian projects they are also not building one in Namibia .
The Namibian project is more ambitious as it will be used also to grow food in the hot and windy conditions under their greenhouse.
too lazy to look up real sources or format, but here are some ideas:
1.6-2 mil per MW construction for coal : ~350 mil for the same power level. ( http://www.jcmiras.net/surge/p83.htm )
$11 per MW-hr for buying the coal : 200 MW is peak power under full sun. Maybe 5 hours per day average of the course of a year gives 5*200*360 = 360,000 MW-hrs per year => 4 mil. per year operating costs saved. Should break even ~100 years, but if I'm too pessimistic by a factor of 3 than it should be about the same, that and you can currently charge more for 'clean' power, maintenance will also be a big factor.
( http://www.nucleartourist.com/basics/costs.htm )
There was a pretty big pilot, entirely successful one, built in Spain at the end of the 80s.
Impractical. Lightning is dramatic(in large part because it wastes most of its energy in hard-to-collect light and sound); but doesn't actually contain that much energy, compared to the needs of even a modestly sized city.
The combination of "hardly enough energy to bother with, once you've averaged it out over the year" and "peak energy high and fast enough to blow a hole through anything not specifically engineered to take it" just isn't very exciting...
Westinghouse makes submarine reactors, by the way.
Note that the solution to nuclear power phobia isn't thousands of nuclear power plants instead of hundreds of them.
Unfortunately, AGW will have to get a great deal worse before we can think about actually adopting a zero emission baseload.
"I do not agree with what you say, but I will defend to the death your right to say it"
Good point. Though any Plexiglas would have to be UV-hardened, else it would get brittle, yellow, and eventually crack in the harsh desert sun.
Bravo, sir. Bravo! Quality trolls are so rare these days! I nearly sprayed beer out of my nose reading this.
While that is all good and true, there will still be government BS on private land as well. I might be off my rocker, but I think they are going to have to get a permit to build something that tall.
Heroscape, it's like legos combined with anachronistic wargames.
Coal plant emit more radioactive material (radon) than nuclear plants
It doesn't matter whether something emits radioactive elements but rather how much is emitted. Living organisms and granite are both naturally radioactive just not enough to cause a problem.
A quick google finds a study indicating that each year 100,000 times more radon is emitted directly by the soil than from coal[1]. Show me a better study that says otherwise and I'll believe you, but until then the radiation argument against coal is bunk.
The same goes for sulfur. The question isn't whether it is emitted, but how much relative to other sources and is it enough to actually matter.
[1] Table 4 in http://www.physics.isu.edu/radinf/radon.htm
They were going to!
Then due to 'OMG! THE ECONOMIC CRISIS!' funding from the financing company dried up, and the local (AU) gov't wasn't interested in stepping in to rescue the project.
You can probably figure out what happened next...
Ole' Ms. Frankenstein there is trying to get certain specific areas of desert protected. Areas which were donated to the government by a private party, and which are known for their ecological importance.
There's nothing sinister about it. It's happening now, because there hasn't been any threat to the areas until solar starting becoming a big thing. And make no mistake, there is TONS of land elsewhere that will do the job just as well... It's just big corporations who didn't give a shit that were willing to destroy a de facto wilderness preserve because it happened to be just slightly more profitable for them.
There's no indication nor even suggestion that Franky will attempt to stamp that label on ANY OTHER AREAS, so there remains enough unprotected desert in So. Cal to supply the power needs of the entire country.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
Radon really is the least troublesome of all of coal's byproducts. You know all this worry about mercury in the ocean, and in our fish (especially that ultra-toxic compound we call methylmercury)? Yeah. Today it mostly comes from coal. Look forward to loads more if it, as China is building coal plants like crazy, and most go completely un-filtered (though I understand the newer plants will tend to implement modern emission control systems, the environment is historically not a major focus of China.
You also have Uranium and Thorium. On average, even though the Uranium and Thorium content of coal is in the 1-10 PPM range, it's amusing to think: were the fissionable material harvested from the coal in some way, it would be capable of of producing nearly as much power as the combustion of its host material itself.
But you're completely right... I bet the use of coal in the 20th century alone contributed more radiation to the environment than the totality of all peaceful nuclear accidents--including Chernobyl. It's just that Chernobyl's emissions tended towards the more energetic.
Dimethylmercury is far more dangerous and it stays around a lot longer than plutonium. How about dioxins?
Like I said, nuclear waste is far from our worst pollutant.
Not in July and August. http://geoplan.asu.edu/aztc/monsoon.html
I still cannot find the droids I am looking for...
Read up on half-lives. The longer the half-life, the less radioactive the substance is. The stuff that will be around for 'millions of years' will only be around that long because it gives off radiation (energy) very slowly.
The stuff that is highly radioactive, on the other hand, 'burns out' much faster. It's more dangerous to us right now, but will will be inert in 'thousands of years'.
How about So. Cal just supply the needs of their own state, THEN we will talk about them supplying the entire country.
Why the pointless redirect? This works just as well and doesn't look like goatse bait.
A giant greenhouse, designed to heat massive ammounts of air, and dump it into the cold upper atmosphere... So we have given up and are going to proactively warm the earth's atmosphere directly now?
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.
True confidence comes not from realising you are as good as your peers, but that your peers are as bad as you are.
It is worth noting that coal occurs as massive rock layers that are pretty much nothing but coal. Uranium ore is disseminated in the host material, so you either need to move a very large amount of non-ore material to get the uranium, or you need to wander around at night with a UV light and Geiger counter trying to find funny looking rocks and petrified wood (where uranium, interestingly enough, tends to accumulate), or otherwise expend considerable effort to locate the stuff, let alone extract it.
Consider mining an underground coal seem. You have to dig a shaft, then shovel out the coal, and you're done. If you're mining a uranium deposit in an underground sandstone bed with just 0.2% uranium ore, then you have to remove 500 units of country rock for each unit of uranium oxide. Then you need to process the rock to remove the uranium oxide, and next process the uranium oxide in to material that can be used as fuel.
Granted, mountaintop removal coal mining is also messy, but your analysis of density of the ore is naive in the absence of a survey of actual data on mining techniques and recovered quantities coal/ore.
Additionally, as uranium deposits are mined out it will probably take more effort than in the past to find new sources, and the cost of uranium will increase. The problem grows worse as demand for uranium goes up. Uranium is not a renewable resource and cost effective reserves are finite. Uranium is expensive to prospect, mine, refine, and dispose of after being used.
You're twisting the facts and you know it.
First of all, some reactors can run on unenriched uranium.
Second, even the reactors that require enriched uranium only need to enrich it up to 3% or so, not all the way up to 100%. You only need to enrich the uranium that high to make a bomb.
My figures were for real uranium you'd actually use. 100% enriched uranium has an energy density closer to 88 million megajoules per kilogram.
One kilogram uranium-235 can theoretically produce about 80 trillion joules of energy (8 × 1013 joules), assuming complete fission
Ah, need to multiply by abundancy, about 0.7%, so that leaves 8*10^13*0.7/100=560 gigajoules.
Still way more than Coal, though.