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This discussion relates to Technology Review's article Solar Thermal Heats Up.

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  ppinheiro76
  

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  07/07/2009 05:55 AM

  Tracking control

  I don't understand the question of the need of having a "special software that costs $100 million to develop runs on a bank of Dell servers. The software coordinates with cheap video cameras that continually monitor the angle of the panels as the sun rises and sets."
  The tracking of celestial bodies (and in this case, the alignment of a mirror to always point the sun's reflection towards a fixed point) is a very easy problem, as the orbit and rotation of the Earth are stable. There are really cheap telescopes that do star-tracking with minimum software/hardware. Deploying a solution based on such hardware (even if modified to cope with larger more powerful servos) would be much more economical.

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  • 
    z0rr0
    

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    07/07/2009 08:29 AM

    Re: Tracking control

    My sentiments exactly - granted, it involves aiming 24,000 panels, but still, the geometry is pretty predictable, I would think.
    Call me jaundiced, but I wonder what Congressional plus up is funding this magnificient piece of software, or are gullible investors more impressed by the smoke than by the mirrors?

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      briang1621
      

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      07/07/2009 05:12 PM

      Re: Tracking control

      "smoke and mirrors!"  Hillarious
      100 Million for software is rediculous the story must be wrong! That 100 million must be for the design and testing of everything.

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      • 
        erbium
        

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        07/09/2009 05:52 PM

        Cheaper tracking control

        if it really cost $100 million, I'm surprised they didn't hire a bunch of illegal aliens, as companies are apt to do in the SW, to simply walk around the field as needed and adjust the mirrors.

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  • 
    carlhage
    

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    07/07/2009 12:13 PM

    Re: Tracking control

    The "$100M" software is to track the mirror focus, not the unreflected sun. If you have imprecise mirrors and/or tracker-mounts, then an open-loop control system where the computer moves the mirror motor to some specific angle won't be precise enough to maintain a calibrated partial-degree angle. (The weight of the mirror might flex the mount, for example.) The solution is trivial-- put a video camera (or a set of 3 or 4) at the tower, and the cameras "see" the field of mirrors. When a mirror is in focus, it will be bright, otherwise not. With one camera, the mirror could move slightly, or with multiple ones, the brighter ones to one side or another indicate a shift is required. Of course, you need something to keep the cameras from melting, e.g. a partial reflector into a pinhole, or an actively cooled pinhole cover (no lens required!).
    
    Once aligned, relative movement of the tracker would be fairly predictable, so a single camera calibration of a mirror might only need a few seconds of back-and-forth movement every few minutes to optimize. Also, the calibration might be pretty similar day-to-day, so the computed tracker motor position should be pretty close.
    
    I don't know if this is really what they do-- it's just what I thought of many years ago when I read the mirror mounts cost $10K each (or whatever it was).
    
    I don't understand why it takes $100M for the software-- they paid too much (or stretched the truth). Seems like $100K is more reasonable. The Keck telescope cost $100M including all the mirrors, actuators, _and_ software. It also uses active focusing to align the mirrors as the telescope moves.

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      briang1621
      

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      07/07/2009 05:34 PM

      Re: Tracking control

      See already one person on this forum solved a problem that cost $100Million for around $100K. This is a testament to the wisdom of the larger community. See how open innovation work, you have a problem and come up with a dumb $100Million solution, then you put the idea out there, and some random guy gives you the solution you were looking for! Maybe I should email "esolar" this Smart solution but they probably will not like it because it is not branded with Dell! Go dell sales guys!
        Dr. Brian Glassman
      Ph.D in Innovation Management
      from Purdue University

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• 
  nekote
  

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  07/07/2009 07:37 AM

  $/kW; ¢/kWh; on a 24/365 basis

  For apples to apples comparison.
  
  $/kW; ¢/kWh; on a 24/365 basis

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  johnsonha143
  

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  07/07/2009 08:40 AM

  Problems with solar

  This is all great, but did they solve any of the traditional problems with solar? Like the night? Or dust settling on the mirrors? Cloudy days?
  
  What we need is a electrical energy storage unit of some type (EESTOR?) to store the energy during times when the sunlight fails.
  
  A hundred mil does sound like a lot for software that tracks the sun, but perhaps it does a bit more like align the mirrors optimally or something.
  
  HJ :O)

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  • 
    dmtk
    

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    07/07/2009 09:44 AM

    Re: Problems with solar

    You can use the wind power while the sun is not shining or one of the grid energy storage methods, wich are becoming more and more popular, or use small biomass plants burning wood cut by sustainable forestry.
    
    Besides the problem "the sun suddenly was obscured by clouds, a.k.a the wind stopped blowing" is no different than the problem "every household turned its oven after coming back from work". What I mean that the fluctuations in the demand of the electricity are no different than the fluctuations in the production of electricity. And we have managed to cope with that at least 40 years ago.

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  • 
    aml
    

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    07/07/2009 10:21 AM

    Re: Problems with solar

    The next generation concentrated solar plants will store energy by heating oil which is held in an insulated tank.  This compensates for short term cloud shadows. 
    
    Also, storage allows for shifting of power to the late afternoon peak need.

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