Sunday, September 4, 2011

This Could Be Big

It might be possible to split water into oxygen and hydrogen using solar energy for the process and a relatively inexpensive semiconductor material. The hypothesis was published in Physical Review B on August 1 of this year. My source is Science News (link). The researchers unveiling this most seductive hint were Professors Mahdu Menon and R. Michael Sheetz, University of Kentucky’s Center for Computational Sciences and Professor Mahendra Sunkara and Graduate Student Chandrashekhar Pendyala, University of Louisville Conn Center for Reneable Energy Research.

The field to which they made their contribution is photoelectrochemical water splitting. The innovation here is the substitution of an inexpensive semiconductor material for much more complex materials used as the base of current experiments. To quote my source, the team at University of Kentucky “demonstrated that an alloy formed by a 2 percent substitution of antimony (Sb) in gallium nitride (GaN) has the right electrical properties to enable solar light energy to split water molecules into hydrogen and oxygen.”

This could be big. But the Big Caution here is that this was a theoretical discovery, not a physical, experimental demonstration. Thus the researchers were modeling chemical outcomes on a computer.

Splitting water into its components using established methods is very energy-consumptive; it uses a lot of electricity. Indeed the energy balance is not favorable; therefore current industrial ways of obtaining hydrogen start with hydrogen-rich methane (4 hydrogen atoms to one carbon). But if we could tweak cheap semiconductors to do the job—with sunlight supplying the external energy yet—that would be a MAJOR breakthrough.

There’s many a slip twixt modeling and demonstration—but I certainly hope these guys are on to something real! To use water (in effect) as the source of fuel—with the exhaust from the engines being water, again, why that would save our high-energy culture—and Fossil Sunset would not be quite so threatening as it is now.

2 comments:

  1. Well now, that's news!
    Something encouraging to watch. Thanks for the heads up.

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  2. I hope this pans out, Monique. I've long thought that something like this *could* be the solution — provided the process doesn't introduce toxics, has good yield per unit of time, and has a favorable energy balance.

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