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Power Hardware

Massive Solar Updraft Towers Planned For Arizona 572

Posted by samzenpus
from the juice-and-a-tan dept.
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."
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Massive Solar Updraft Towers Planned For Arizona

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  • by n0tWorthy (796556) on Wednesday January 06, 2010 @07:54PM (#30676928)

    They should build it in Washington DC

    • A giant sun tower or two in Arizona is an interesting idea. But it makes more sense to build a huge lightning capacitor.

      There's this place in Arizona where lightning strikes are common and happen nearly every night. Something in the atmosphere, the heat, and humidity.

      So why not dig a huge hole in the ground, fill it with aluminum foil and electrolytic, then quickly and carefully build a huge lightning rod. The lightning will constantly arc to the giant million farad capacito

      • by fuzzyfuzzyfungus (1223518) on Wednesday January 06, 2010 @10:41PM (#30678272) Journal
        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...
    • by Tehrasha (624164)
      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?

      • Re:Green Energy? (Score:4, Insightful)

        by The End Of Days (1243248) on Wednesday January 06, 2010 @09:48PM (#30677926)

        Maybe there's something I'm missing, but I'm pretty sure all the energy that the sun will dump into these greenhouses was going to end up there anyway...

        • Re: (Score:3, Insightful)

          Probably, but given our habit of causing tomorrows problems with today's solutions it would not be too surprising.
      • Re: (Score:3, Insightful)

        by osu-neko (2604)

        Might I suggest that instead of dumping the warm air into the upper atmosphere, we pump it to Minnesota? Please?

        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 (although when you consider the waste heat when the energy is used, it probably all balances out in the end -- well, it would have to, wouldn't it, unless you're suggesting

        • Re: (Score:3, Interesting)

          by KlaymenDK (713149)

          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.

      • It's a greenhouse. It has no heaters other than concentrating the sun's warmth. Have you and the moderators lost all sense of reality, forgotten what words mean, gone cuckoo?

        Every time I think I've met and accounted for those idiots who confound my idiot-proof programs, I find that nature is preparing the batch right under my nose.

      • Re:Green Energy? (Score:4, Insightful)

        by cyn1c77 (928549) on Thursday January 07, 2010 @03:03AM (#30679754)

        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?

        Don't confuse controlled convection with global warming. The ground everywhere always absorbs sunlight, which heats it and the air near the ground. That air then ruses upwards. All they are doing is putting a roof over the hot ground to channel the air into a turbine. It's analogous to building a dam in a river to harness potential energy that is normally wasted. The earth doesn't absorb any more energy than it normally would... unless they are lowering the albedo of the ground under the greenhouse. Of course, it would be more efficient for them to paint the ground black.

        If they did color the ground, you would have increased global energy absorption. (Much like you get frmo using solar panels...) But you would also be generating CO2 free energy, so you could burn less coal. In the end, lowering CO2 values would win out, since with less greenhouse gases in the air, the more heat would be radiated back out to space. And that is ignoring the carbon savings from not having to mine as many coal or hydrocarbons.

        They should put these over parking lots in hot areas of the world. Or maybe we could just put a big one over Texas. They all use air conditioning there anyway, so they would never know the difference.

      • Re:Green Energy? (Score:5, Informative)

        by fbjon (692006) on Thursday January 07, 2010 @03:31AM (#30679890) Homepage Journal

        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.

        • Re: (Score:3, Interesting)

          by mcvos (645701)

          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: (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

    • 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 st

  • by Rei (128717) on Wednesday January 06, 2010 @07:59PM (#30676968) Homepage

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

    • by TubeSteak (669689) on Wednesday January 06, 2010 @10:04PM (#30678046) Journal

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

      It is estimated that it would be possible to establish a self-sustaining vortex to demonstrate the feasibility of the process with a station 30 m in diameter under ideal conditions. Learning to control large vortices under less than ideal conditions would be a major engineering challenge. Developing the process will require determination, engineering resources; and cooperation between engineers and atmospheric scientists. There will be difficulties to overcome, but they should be no greater than in other large technical enterprises.

      Translation: I can haz millions for R&D?

      OTOH, Solar Chimneys can be built today.
      So I'm guessing that's why Arizon isn't using an undeveloped technology that may not even be workable.

  • Efficiency (Score:5, Interesting)

    by pete-classic (75983) <hutnick@gmail.com> on Wednesday January 06, 2010 @08:04PM (#30677018) Homepage Journal

    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

    • by Rei (128717) on Wednesday January 06, 2010 @08:20PM (#30677160) Homepage

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

      Yes. Yes.

    • Re:Efficiency (Score:5, Interesting)

      by dbIII (701233) on Wednesday January 06, 2010 @08:45PM (#30677386)

      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.

  • by Anonymous Coward on Wednesday January 06, 2010 @08:13PM (#30677086)

    A nuclear plant would use maybe 50 acres and produce a gigawatt. I think the capital expense is comparable. What is the benefit here?

    Regards,
    Jason

    • by bmk67 (971394) on Wednesday January 06, 2010 @08:21PM (#30677176)
      It doesn't generate a shitload of radioactive waste, perhaps?
      • by wizardforce (1005805) on Wednesday January 06, 2010 @08:31PM (#30677248) Journal

        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.

    • by Chris Burke (6130) on Wednesday January 06, 2010 @08:51PM (#30677430) Homepage

      Land use is not exactly a big issue in Arizona...

  • by catalina (213767) <jmattclark@noSpam.gmail.com> on Wednesday January 06, 2010 @08:14PM (#30677096) Homepage Journal
    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.....
  • dumb question? (Score:3, Interesting)

    by girlintraining (1395911) on Wednesday January 06, 2010 @08:20PM (#30677166)

    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:dumb question? (Score:5, Informative)

      by Weedhopper (168515) on Wednesday January 06, 2010 @08:39PM (#30677318)

      Many, if not most wastewater (sewage) treatment plants in the US produce a net energy surplus, which is then returned to the grid.

      • Re:dumb question? (Score:5, Interesting)

        by cptdondo (59460) on Wednesday January 06, 2010 @09:24PM (#30677710) Journal

        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: (Score:3, Insightful)

      by MichaelSmith (789609)

      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.

      The system relies on having a high air temperature at ground level so that the hot air rises up the column and remains hotter than the surrounding air as it rises. My suspicion is that the air just above the ground will be hotter than rock 500 metres down, but probably not much further. You need a good temperature gradient to extract heat so you would have to go very deep to get a good gradient WRT the surface air. This might work at night or in a colder climate, but when you think about it it just becomes

  • by assemblerex (1275164) * on Wednesday January 06, 2010 @08:32PM (#30677258)
    profit! Half mile high tower? Pffft
  • by LostCluster (625375) * on Wednesday January 06, 2010 @08:37PM (#30677300)
    George W. Bush is already scheming how to dodge the updraft.
  • Spain Too (Score:3, Interesting)

    by LoudMusic (199347) on Wednesday January 06, 2010 @09:08PM (#30677586)

    Spain is doing something similar. But different.

    http://www.power-technology.com/projects/Seville-Solar-Tower/ [power-technology.com]

  • by jcr (53032) <jcr&mac,com> on Wednesday January 06, 2010 @09:09PM (#30677604) Journal

    Anyone have the figures for the cost of conventional generating facilities that, you know... Work when the sun's not shining, too?

    -jcr

  • by sp3d2orbit (81173) on Wednesday January 06, 2010 @09:57PM (#30678004)

    The project will decimate 2000 acres of desert habitat for 200 megawatts output. Palo Verde nuclear power plant, also in Arizona, spans 4000 acres of desert and produces 3.2 gigawatts.

    Nuclear power is 8x more efficient in land use alone.

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