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Silicon Nanoparticles Could Lead To On-Demand Hydrogen Generation 163

Posted by samzenpus
from the just-add-water dept.
cylonlover writes "Researchers at the University of Buffalo have created spherical silicon nanoparticles they claim could lead to hydrogen generation on demand becoming a 'just add water' affair. When the particles are combined with water, they rapidly form hydrogen and silicic acid, a nontoxic byproduct, in a reaction that requires no light, heat or electricity. In experiments, the hydrogen produced was shown to be relatively pure by successfully being used to power a small fan via a small fuel cell."
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Silicon Nanoparticles Could Lead To On-Demand Hydrogen Generation

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  • by R_Ramjet (994878) on Friday January 25, 2013 @09:17AM (#42689731)
    Significant. From the article: "Though it takes significant energy and resources to produce the super-small silicon balls, the particles could help power portable devices in situations where water is available and portability is more important than low cost."
  • by Stirling Newberry (848268) on Friday January 25, 2013 @09:39AM (#42689879) Homepage Journal
    Actually the LCA of petroleum is excellent, that's one of the reasons it took over the world.

    It just has unfortunate side effects: it is killing us, and killing our ecosystem, which we are rather dependent on, there being no other garden worlds.

  • by DeathToBill (601486) on Friday January 25, 2013 @09:52AM (#42689983) Journal

    Um, no. It typically takes around 4MJ/L (just over 1kWhr/L) to refine petrol, while the energy content is 35MJ/L. Drilling and transport add a little to that, but it's negligible compared to refining it. If it wasn't so, using it would have a net negative impact on our energy supply and no-one would use it.

  • by ciggieposeur (715798) on Friday January 25, 2013 @10:07AM (#42690101)

    Indeed. I work for one of the major "silicon crushers". Converting sand to metallurgical grade silicon (97%+) takes an arc furnace, lots of electrical power required. Then comes grinding and classifying it and most processes deliberately spray the dust with water to put an oxide layer on the particles to prevent a dust explosion.

  • by Anonymous Coward on Friday January 25, 2013 @11:05AM (#42690689)

    No need to, the oxygen wasn't in the atmosphere, it was bound to the hydrogen in the water molecules. Water is burned hydrogen, so this oxygen was already "lost".

  • Re:Honest, Officer (Score:4, Informative)

    by richtopia (924742) on Friday January 25, 2013 @11:36AM (#42691073)
    Keep in mind that hydrogen burns clear, so it will be pretty hard for the officer to discover the fire
  • by rgbatduke (1231380) <rgb AT phy DOT duke DOT edu> on Friday January 25, 2013 @11:52AM (#42691255) Homepage

    Where does silicon come from? Silicon dioxide, a.k.a. "sand". How tightly is it bound? Very, very, very tightly. Indeed, a whopping 910.86 kJ/mole. So it requires at LEAST this much energy to turn sand into silicon and oxygen, except that one cannot electrolyze or reduce it until it is molten, so add to this enough energy to melt sand, after raising its temperature to some 1500 C. Then, one has to engineer "nanoparticles" out of the purified silicon metal. At a guess -- only a guess, of course -- this involves heating the silicon to the vaporization point and either vapor depositing it on a suitable substrate and scraping off the nanoparticles or spraying silicon vapor into a suitable medium that causes it to condense out small particles and then filtering or otherwise separating out the 'nano' particles from those that are merely small. Sounds like more energy to me.

    At the end of the day, you can get at most the 250 or so kJ/mole back from the hydrogen gas produced after the silicon nanoparticles steal the hydrogen back from water. I think it would be an absolute miracle if it this is as much as 10% of the energy invested in making the nanoparticles, and the energy costs are probably at most half of the total manufacturing costs. Down to 5%. Multiply by roughly 50% again (efficiency of fuel cell).

    This "Fermi estimate" of the probable economic efficiency is on the order of 2.5%, then, compared to the cost of just buying electricity or any other form of concentrated energy. Even if I'm too aggressive in my pessimism, 10% is a pretty safe upper bound. I'm not seeing this as a game changer. Gasoline or other hydrocarbons are still the gold standard for readily available energy density at ballpark 35 MJ/liter, and don't require investing 20 times the energy eventually recovered in their preparation.


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