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Scientists Use Microbes to Produce Hydrogen
An anonymous reader writes " Environmental engineers at Penn State University and a research scientist at Ion Power Inc. have created an electrically-assisted microbial fuel cell that can be used to produce hydrogen from organic material. The amount of electricity needed for the process is less than the amount required to power a standard cell phone. This advancement can be used to produce hydrogen as a byproduct of water treatment. " Coverage at ScienceDaily as well.
You'll be splitting distilled water just like the rest of us, matey, and leave the tap water going down the drain. :-)
I've fallen off your lawn, and I can't get up.
Complain about Slashdot all you want, but the articles and the original press release are all missing the details you want. This is a case where the only details that have been reported have been gleaned from a press release, only published two days ago. It will take a while before a journalist asks the kind of questions you want asked.
Slashdot is not a news site. There aren't a group of reporters doing fact checking. It is new aggregation and community site.
here they are
pdf with the original paper here
The actual paper referenced is Electrochemically Assisted Microbial Production of Hydrogen from Acetate by Drs Hong Liu, Stephen Grott, and Bruece E. Logan from Penn State, in the publication "Environmental Science and Technology."
Enjoy...
According to the abstract:
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The requested URL
Well, conventionally, a fuel cell is merely the device that can utilize hydrogen to produce electricity. Fuel cells do not store hydrogen at all, they rely on a another device to store or produce the hydrogen. Typically, that will be a compressed gas or liquid H2 tank in the case of storage or a natural gas or methanol reformer in the case of production. I agree that the article is a bit misleading. But the way I interpreted it, they are using the hydrogen produced by the bacteria "real-time" as opposed to storing it and then using it in a fuel cell. In other words, the produced hydrogen is being directly fed into a fuel cell to produce electricity. Now if one was to scale up this technology for a wastewater plant, the hydrogen could be used immediately in a fuel cell to produce grid power, but could also be stored as power demand decreases throughout the day. This stored hydrogren could then be used to produce more grid power upon demand or delivered to vehicles powered by fuel cells.
Hydrogen is produced when the bacteria exchanges a proton for an electron at the anode. The proton becomes the hydrogen.
thus it is one for one. For every hydrogen produced you have one electron dropping through a 0.25v external potential.
If other processes are also transferring protons then that's still hydrogen. So one electron passed means some proton contianing species ended up on the electrode. as long as you can make sure that those are mainly hydrogen and not some weird thing (say a metal or sodium or soduim), then you dont care.
So basically its a 0.25 volt cost atom produced.
Now to the numbers: One mole of electrons is the same as 96,500 Coulombs. So producing 96,500 would require about 25 kilo joules of energy. A mole of hydrogen, if I recall correctly, contains 280KJ of energy of which 230KJ is extracable as work (rest has to to to heat to pay the boltzman tax).
Of course the bacteria can also produce hydrogen on it's own. THe problem is the build up of reaction products that shut down the process. the current is used to help the bacteria get rid of these so the reaction can go to completetion producing hydrogen. Thus if I read this right in steady state we are indeed exchaning electrons for each hydrogen. The problem would then be if the bacteria is instead exchanging electrons for methane or something we dont want.
I cant quite figure out the abstract of the science paper but it sounds like they get about 80% of what they want.
Some drink at the fountain of knowledge. Others just gargle.
well why... this carbon is coming from active biomass and thus not increasing the co2 content of the athmosphere.
And compared to just burning wood, ect it is cleaner because of the lack of NOx, CO,...
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
Volts x Amps = Watts.
Electricity is measured in watts. That is why your electric bill is measured in watts. (and not volts.)
The article did not tell us enough to determine whether there had indeed been a boost in the ideal efficiency of hydrogen production.
If it had said 1 watt and 1 lb of lawn clippings had been used by the microbes to store 1 kilowatt hour's worth of hydrogen then that would be pretty interesting. For those who care.
"0.25 volts" could be measuring 0.25 volts at 30 amps or at 1000 amps. The article didn't mention amps. And even if it had, it didn't tell us how much hydrogen was generated. Nor did it tell us what percent efficiency the reaction had been. Nor did it give us a comparison between microbial hydrogen production's efficiency and that of standard electrical electrolysis.
Anyhow, perhaps there was a genuine breakthrough, but the article doesnt describe enough to get me excited.
"Forgive us our trespasses, as we forgive those who trespass against us." -Jesus Christ The Lord's Prayer