The main problem with ethanol is that the potential chemical energy it
contains is rarely equal or higher than the energy required to produce
it. Furthermore, the conversion efficiency of an ethanol fuel cell would
be a lot lower than the energy obtained by its combustion. This is
because the fuel cell would "use" only the 6 H atoms in the molecule,
ignoring the two C atoms, whereas combustion would "use" them, as well.
However, the use of pure ethanol is fraught with other problems, not the
least of which is its violent hygroscopicity until it reached its
azeotrope at about 96% EtOH. The presence of such water would not be
good for fuel cells. IMHO, MeOH would be a better liquid fuel for FCs
(higher H:C ratio, less hygroscopic, more toxic, though)
Also, the indiscriminate use of nanoparticles scares the pants off me.
We have no clue what the effect of them is likely to be.
Brian
Safety wrote:
> Ahh... more on Ethanol. Perhaps it's time to go invest in Bluefire Fuels after all.
> Although, I'm more surprised to see a post on environet than to see news of a revolutionary synthetic catalyst.
>
> Thanks for the news, sir!
>
> -----Original Message-----
> From: EnviroNet [mailto:[log in to unmask]] On Behalf Of Joe Fjelstad
> Sent: Tuesday, January 27, 2009 1:28 PM
> To: [log in to unmask]
> Subject: [EN] Breaking carbon�s tough bonds for fu el (Brookhaven Labs development)
>
>
> Breaking carbon�s tough bonds for fuel
>
>
> Jan. 27, 2009
>
> A team of scientists at the U.S. Department of Energy's (DOE) Brookhaven
> National Laboratory, in collaboration with researchers from the Univ. of
> Delaware and Yeshiva Univ., has developed a new catalyst that could make
> ethanol-powered fuel cells feasible. The highly efficient catalyst performs two crucial,
> and previously unreachable steps needed to oxidize ethanol and produce clean
> energy in fuel cell reactions. Their results are published online in the
> Jan. 25 edition of Nature Materials.
>
> Like batteries that never die, hydrogen fuel cells convert hydrogen and
> oxygen into water and, as part of the process, produce electricity. However,
> efficient production, storage, and transport of hydrogen for fuel cell use is not
> easily achieved. As an alternative, researchers are studying the
> incorporation of hydrogen-rich compounds, for example, the use of liquid ethanol in a
> system called a direct ethanol fuel cell.
>
> "Ethanol is one of the most ideal reactants for fuel cells," said Brookhaven
> chemist Radoslav Adzic. "It's easy to produce, renewable, nontoxic,
> relatively easy to transport, and it has a high energy density. In addition, with
> some alterations, we could reuse the infrastructure that's currently in place to
> store and distribute gasoline."
>
> A major hurdle to the commercial use of direct ethanol fuel cells is the
> molecule's slow, inefficient oxidation, which breaks the compound into hydrogen
> ions and electrons that are needed to generate electricity. Specifically,
> scientists have been unable to find a catalyst capable of breaking the bonds
> between ethanol's carbon atoms.
>
> But at Brookhaven, scientists have found a winner. Made of platinum and
> rhodium atoms on carbon-supported tin dioxide nanoparticles, the research team's
> electrocatalyst is capable of breaking carbon bonds at room temperature and
> efficiently oxidizing ethanol into carbon dioxide as the main reaction
> product. Other catalysts, by comparison, produce acetalhyde and acetic acid as the
> main products, which make them unsuitable for power generation.
>
> "The ability to split the carbon-carbon bond and generate CO2 at room
> temperature is a completely new feature of catalysis," Adzic said. "There are no
> other catalysts that can achieve this at practical potentials."
>
> Structural and electronic properties of the electrocatalyst were determined
> using powerful x-ray absorption techniques at Brookhaven's National
> Synchrotron Light Source, combined with data from transmission electron microscopy
> analyses at Brookhaven's Center for Functional Nanomaterials. Based on these
> studies and calculations, the researchers predict that the high activity of
> their ternary catalyst results from the synergy between all three constituents�
> platinum, rhodium, and tin dioxide�knowledge that could be applied to other
> alternative energy applications.
>
> "These findings can open new possibilities of research not only for
> electrocatlysts and fuel cells but also for many other catalytic processes," Adzic
> said.
>
> Next, the researchers will test the new catalyst in a real fuel cell in
> order to observe its unique characteristics first hand.
>
> This work is supported by the Office of Basic Energy Sciences within DOE's
> Office of Science.
>
> The abstract to this study is available here,
> _http://www.nano-biology.net/showabstract.php?metaid=165122_
> (http://www.nano-biology.net/showabstract.php?metaid=165122)
>
> Brookhaven's Center for Functional Nanomaterials, _http://www.bnl.gov/cfn/_
> (http://www.bnl.gov/cfn/)
>
> SOURCE: Brookhaven National Lab
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