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This discussion relates to Technology Review's article Solar-Power Breakthrough.

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  brock_cusick
  

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  07/31/2008 03:23 PM

  Solar is just an application

  If I understand this correctly, this is a method for using electrical power to produce hydrogen fuel. Why the focus on solar? Isn't this just as beneficial for wind? Wouldn't using nuclear baseload power to produce H2 fuel to meet peakload demand or motive power also make sense?
  
  I'm sure this technology is revolutionary, but (unless I am mistaken) the implications are far broader than this story makes out. It's almost misleading. Am I wrong?

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  • 
    Kevin Bullis
    

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    07/31/2008 05:18 PM

    Re: Solar is just an application

    In some ways you're right. The system can use electricity from any source. But there are a couple of reasons to focus on solar. First, the ultimate goal of the research is artificial photosynthesis, because solar power is the biggest source of energy we've got.
    
    The second is a more practical issue. Note that, near the end, the article talks about the need to improve the rate of oxygen production. Right now, the rate is very close to what would be needed in artificial photosynthesis, but not fast enough to be practical in conjunction with wind power or other sources of electricity, according to NREL's John Turner.
    
    Let me know if you want more details on that. 

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    • 
      MyTrac
      

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      08/01/2008 02:20 PM

      Re: Solar is just an application

      Kevin, I would appreciate more imformation on that.
      
      TIA

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        Kevin Bullis
        

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        08/01/2008 05:28 PM

        Re: Solar is just an application

        Here's what John Turner of NREL says. In the case of artificial photosynthesis, the catalyst would be incorporated directly into a solar panel system that includes materials that absorb sunlight and generate electrons, membranes, and the catalyst that converts protons into hydrogen gas.
        
        In such a system, the catalyst wouldn't be supplied with much of a current, which translates into pretty slow rates of water splitting. It'd be on the order of 30 to 40 mA/cm^2. Nocera says his catalyst works at about 5 mA/cm^2, so it's pretty close.
        
        But if you don't have an artificial photosynthesis system, you are going to need two separate devices: the electricity generator plus a separate electrolyser that includes Nocera's catalyst. That's going to cost more. You can minimize these capital costs if you have catalyst that works at a higher current density and produces hydrogen at a faster rater (the faster, the smaller the system you need). There are also space considerations. In this case, you'd probably want a catalyst that works at high current densities. Today's, albeit expensive, electrolysers, for example, can work at 800 mA/cm^2 or more. It seems likely that you wouldn't need to go quite that far, since Nocera's system would be cheaper. But you'd want significantly higher densities than 30 to 40 mA/cm^2, Turner says.
        
        Nocera actually has a different take. He thinks electrolysers based on his catalysts could be cost effective using photovoltaics as the power source, provided the current densities are improved a bit. This is especially true if you are using only part of the current from the PVs to power the electrolysis, using the rest to power your home during the day. 

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  • 
    MitchJi
    

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    08/02/2008 08:59 PM

    Re: Solar-Power Breakthrough

    Hi,
    
    I don't see any advantage compared with Solar Thermal combined with heat storage.
    
    Creating and storing heat is bound to be more efficient and less expensive.  Also storing hydrogen takes a lot of space. 
    
    Maybe for homes or other small installations or if Hydrogen Automobiles ever become practical (maybe in 30 or 40 years?).

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    • 
      LDighera
      

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      08/06/2008 09:12 AM

      Re: Solar-Power Breakthrough

      "... if Hydrogen Automobiles ever become practical (maybe in 30 or 40 years?)."
      
      It would appear that Honda is putting hydrogen fueled automobiles in the hands of consumers in California TODAY:
      
      TORRANCE, USA, July 25, 2008, 2008 - American Honda Motor Co., Inc.,
      announced that Ron Yerxa and Annette Ballester took delivery of their
      hydrogen fuel cell-powered FCX Clarity on Friday, July 25, 2008 at
      Honda of Santa Monica, one of three dealerships in Southern California
      that are part of the first fuel cell vehicle dealership network.
      
      Full Story:
      http://world.honda.com/news/2008/4080725FCX-Clarity/
      
      Photo Index (3 photos):
      http://world.honda.com/news/2008/4080725FCX-Clarity/photo/

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    aldecal
    

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    08/03/2008 01:17 PM

    Re: Solar is just an application

    Is it possible to isolate the light frequencies that can be reproduced. To accomplish the same end results?

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  GaryB
  

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  07/31/2008 04:26 PM

  Hydrogen ions

  Hopefully this is a real advance, we'll be needing it ... and the real way to "win" the war on terror is to get off of oil.
  
  But, apparently he splits oxygen and also produces hydrogen ions.  It's unclear what this means.  Does the process produce:
  Two H^+
  H_3O^+
  other?
  Depending on the exact output, this process is more or less useful.

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  • 
    Kevin Bullis
    

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    07/31/2008 05:23 PM

    Re: Hydrogen ions

    It's making protons.

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  jpm000001
  

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  07/31/2008 07:40 PM

  Oh no!

  Once this technology becomes widespread, we're going to run out of drinking water!

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  • 
    javs
    

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    08/01/2008 08:27 AM

    Re: Oh no!

    Even without this breakthough, we are running out of drinking water. Kevin, can this work on sea water?

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    • 
      Kevin Bullis
      

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      08/01/2008 09:06 AM

      Re: Oh no!

      Dr. Nocera says that the system is flexible--it can be adapted to work with water that has different impurities. It looks likely, he says, that it could be made to work with sea water.

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        javs
        

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        08/01/2008 06:24 PM

        Re: Oh no!

        Thanks! Working on non drinkable water is very important as the water ecosystem services get close to depletion. That way the biofuels vs. food story is not repeated.

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          Tomek
          

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          08/02/2008 09:56 AM

          Re: Oh no!

          If I'm right, we do not have to worry about our water supplies since the system described here does not use any water! Yes, water molecules are being split into protons and oxygen molecules in the process, but as soon as you extract the energy stored in the form of oxygen and hydrogen, you will get all the water back as well.

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      rttedrow
      

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      08/01/2008 09:39 AM

      Re: Oh no!

      If it did not work on seawater it could power the desalinization process.

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      • 
        javs
        

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        08/01/2008 06:29 PM

        Re: Oh no!

        Desalination is improving, but it seems to me that is still a very energy intensive proposition.

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    • 
      wmccampbell
      

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      08/01/2008 09:40 AM

      Re: Oh no!

      Isn't any water lost in the electrolysis process regained when the hydrogen is run through a fuel cell?  This could theoretically increase the supply of drinking water by using non-potable water as the input and the ultimate output being pure water.

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    frestred
    

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    08/03/2008 06:26 PM

    Re: Oh no!

    im so worry about the source of energy that becomes the water, if the water today is a precius resource and is so scarce, if it is used as a source of power what would happen with us, all of us know the hungry of energy of this planet, rigth now there problems with the biodiesel, etc,that put the foods in the clouds, what would happen with the water when this discovery becomes commercial?

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