Slashdot Mirror
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.
I have been using microbes to produce methane for a while now, why can't I run my computer from that?
Need extra power for that long haul flight, just eat a curry before hand!
liqbase
I need this, the amount of unwashed dishes and dirty laundry lying around could turn my entire apartment into a megastore of cheap energy!
less than the amount required to power a standard cell phone
What is that in Libraries of Congress per Electronic Arts business day?
The amount of electricity needed for the process is less than the amount required to power a standard cell phone.
To power what? A 100-gallon microbial fuel cell or a very teensy one?
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
- One hundred thousand megatons of hydrogen are produced by less energy than is required to power a cell phone for one nanosecond.
- One molecule of hydrogen is produced by less energy than is required to power a cell phone from the moment it is activated with a completely charged battery until the moment it shuts off because its battery becomes completely discharged.
This is what I love about Slashdot articles.And what does that say? Nothing. I'm pretty sure I can create a couple of hydrogen molecules with that amount of electricity too and I won't even need any bacteria in the process.
Here's a more useful bit from the article, though it would be even more useful if they would just say what fraction of energy this process requires:
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.
here they are
Did the Volt turned into a unit of power while I was sleeping? And I thought I did well in physics.
Tharkban (It is a signature after all)
pdf with the original paper here
The less than the amount required to power a standard cell phone statement is totally meaningless because it gives no indication of the efficiency of the process. Even at "0.25V", if the process requires tens or hundreds of electrons per molecule of hydrogen, then the process may be horribly inefficient. Even the "produces four times more hydrogen than would be typically generated by fermentation alone" is meaning less without some facts such as the molar conversion efficiency -- how many moles of hydrogen per mole of acetate does the augmented process create?
Moreover, this process is not the holy grail of pure electrolysis (e.g., splitting water into hydrogen and oxygen), it is an electrolyticly augmented chemical conversion of carbohydrates into carbon dioxide (green house gas), water, and hydrogen. In theory, this process could by part of a biomass-to-hydrogen fuel generation cycle, but as we have seen with ethanol production, the amount ethanol-based energy harvested is poor in comparison with the energy required to grow, reap, and process the plants (corn).
Don't get me wrong, this is a very intriguing finding, but there is far too little information in the article to determine if this process is thermodynamically better or worse than simply burning the carbohydrates in a furnace or standard combustion engine.
What frustrates and saddens me is that the analysis needed to make useful statements about this discovery are not that hard to make. Any competent chemist or chemical engineer could provide a useful back-of-the-envelop estimate of the energy inputs and outputs given an afternoon with the raw data from the experimenters. Either the scientists involved did not do this analysis (shame on them) or the journalists chose to ignore key results (shame on them) or the actual return on energy input is very poor indeed (to bad for all of us).
I hate articles that quote meaningless comparisons and leave the true question of practically total unanswered while holding out a vaporous promise that our energy problems are solved.
Two wrongs don't make a right, but three lefts do.
Your digestive system requires (and produces) various enzymes to digest different foods. Without the proper enzymatic mix, digestion is inefficient and a gaseous output results.
To get a decent methane volume, you have to vary your diet in a pathological way. Eat a sudden excess of foods you seldom eat. Try a progresson of beans - kidney beans, great whites, navy beans, blackeyed peas, and of course, the dreaded garbanzo. Mix in some onion varieties periodically. Then there are the peppers: bell peppers, jalapenos, and even habaneros are very efficient in terms of obtaining the desired output.
Stay away from rice and noodles, as these seem to lessen the effect.
I understand that certain vegetables - broccoli, cauliflower, asparagus, for example, can also have dramatic benefits if consumption is managed properly as above.
Unripe apples and certain kinds of nuts are good candidates, but I find them to quickly lose their efficacy, and so they should be either reserved for a special occasion (such as a wedding or funeral) or simply enjoyed for their non-flatulent properties.
Raise your children as if you were teaching them to raise your grandchildren, because you are.
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...
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?
Totally missing from the article, and the abstract:
Does the process produce as much fuel as is necessary to fuel the process? More? Less?
What's that you say? The article cleary states that this process is cheaper than the old process?
Great! But is it cheap *enough*?
Any sufficiently well-organized community is indistinguishable from Government.
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.
Combined with a form of fusion, the machines have found all the energy they would ever need.
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