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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.
From the article -
Using a little amount of electricity - about 0.25 volts - scientists at Pennsylvania State University found that a microbial fuel cell can overcome its "fermentation barrier", Xinhua reports.
The voltage is just one-tenth needed for electrolysis - the process that uses electricity to break water down into hydrogen and oxygen.
...and...
The voltage to be given, scientists explain, is a small fraction of the voltage needed to run a typical six-volt cell phone.
RTFA next time. The headline on the front page isn't everything. The article doesn't answer specifics on the amount of hydrogen produced, but it does imply alot of things about the overall efficiency of the process.
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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.
"Does it scare anyone else how lazy our news media has gotten?"
Go back to sleep and don't worry about it. Your politicians have it covered.
Deleted
Power is not voltage alone. And like you mentioned, it doesn't at all state the amount of hydrogen created or whether the efficiency is high enough that more energy isn't consumed in the production than is able to be used from the resultant hydrogen. Regardless, I suppose it's good news; increased efficiency is increased efficiency.
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here they are
pdf with the original paper here
A Fuel cell, if I am not mistaken, is a device for storing hydrogen and extracting electricity from hydrogen once stored.
However the linked article talks about "fuel cells", but then talks about this "fuel cell" as producing hydrogen-- as if for some kind of process that would be used to produce hydrogen for use in fuel cells.
What am I missing here?
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The process also produces good old CO2. You know, that nasty greenhouse gas. Not the environmentally friendly solution that it is spun as.
Interesting research, but until the CO2 problem is solved it still needs work.
You'll need tanks, proton exchange membranes, electricity and some sort of feedstock. Plus compressors or cryo coolers, pumps etc.
Maybe someone will package it all up into a handy wee box. Or maybe with the increasingly rapid advancements in battery technologies it'll be easier to just plug a battery vehicle into the mains, or the solar panel you have on the roof of your house.
Deleted
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:
Not Found
The requested URL
RTFA (#2) -
.25V starts the process going, and that further research will show how many can be produced/costs/etc.
However, giving the bacteria a small assist with a tiny amount of electricity -- about 0.25 volts or a small fraction of the voltage needed to run a typical 6 volt cell phone -- they can leap over the fermentation barrier and convert a "dead end" fermentation product, acetic acid, into carbon dioxide and hydrogen.
Logan notes, "Basically, we use the same microbial fuel cell we developed to clean wastewater and produce electricity. However, to produce hydrogen, we keep oxygen out of the MFC and add a small amount of power into the system."
In the new MFC, when the bacteria eat biomass, they transfer electrons to an anode. The bacteria also release protons, hydrogen atoms stripped of their electrons, which go into solution. The electrons on the anode migrate via a wire to the cathode, the other electrode in the fuel cell, where they are electrochemically assisted to combine with the protons and produce hydrogen gas.
A voltage in the range of 0.25 volts or more is applied to the circuit by connecting the positive pole of a programmable power supply to the anode and the negative pole to the cathode.
The researchers call their hydrogen-producing MFC a BioElectrochemically-Assisted Microbial Reactor or BEAMR. The BEAMR not only produces hydrogen but simultaneously cleans the wastewater used as its feedstock. It uses about one-tenth of the voltage needed for electrolysis, the process that uses electricity to break water down into hydrogen and oxygen.
Logan adds, "This new process demonstrates, for the first time, that there is real potential to capture hydrogen for fuel from renewable sources for clean transportation."
Basically, this is saying that
-Hell hath no fury like that of a woman scorned for
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.
the 0.25 v is the potential drop per hydrogen atom produced. it scales. a 100 gallon reactor would have the same potential drop as a 1 gallon reactor. the cost scales too. just multiply atoms per second * 0.25v / 1.6e18 (atoms/coulomb). you dont need to know the current just the voltage and you can compute the power per volume.
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?
Voltage is not an amount of electricity. That's like saying you need 10 psi of air. If you're blowing up a balloon that's great, if you're blowing up a tractor tire that's a problem.
Almost every wastewater plant you see has a big flame stack in the back where they burn off the excess methane not used for heating the biomass or the building. It seems to work quite well, so why don't we just convert that to electricity or put it in gas mains?
Is this process inherently more efficient in producing hydrogen instead?
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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.
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