Filed under: Emerging Technologies, Hydrogen
Vinegar + water + bacteria + electrons = hydrogen?
Currently the most cost effective means of producing hydrogen is through steam reformation of natural gas. While this process is efficient, it does produce CO2. Electrolysis of water produces only oxygen and hydrogen but takes more electricity than the energy you can get from the hydrogen produced and is at best 50-70 percent efficient. Bruce Logan and Shaoan Cheng of Penn State University may have devised a mechanism that can produce more hydrogen energy than the energy that must be added to the process. They have developed a bacterial electrolysis cell that can consume a variety of organic compounds and produce hydrogen with only a small amount of electricity added to the process. The total efficiency of hydrogen production ranges from 63 percent for cellulose to 82 percent for acetic acid (vinegar) when both the electricity and the energy in the feedstock are factored in. The process produces 144 percent more hydrogen energy than the amount of electricity added. If the process can be scaled up it could be a major breakthrough in carbon-free hydrogen production.
[Source: PhysOrg, thanks to Jason for the tip]
Reader Comments (Page 1 of 1)
Harvest 11:40AM (11/13/2007)
Bacterial Electrolysis has been around for a while. There's some more research currently being done to use it to produce hydrogen from the massive amount of glycerol waste being produced from bio-diesel production.
http://aiche.confex.com/aiche/2007/preliminaryprogram/abstract_100979.htm
Generating Hydrogen relatively carbon free from bio-diesel production waste? I'm lovin' it.
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Jason 1:41PM (11/13/2007)
"....have devised a mechanism that can produce more hydrogen energy than the energy that must be added to the process."
What does the first law of thermodynamics say about this?
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Lou Grinzo 2:50PM (11/13/2007)
Jason: The first law of thermodynamics says the same thing about this that it does about the way we get more energy out of the oil we pull out of the ground than we expend to get it: It only looks like a violation if you do your accounting wrong.
Given the source of this work (i.e. a major US university), I have no doubt the claims about energy flows are accurate. The concern is the CO2 production. Logan has a presentation online (Google it) that shows that you get two molecules of CO2 for every 4 molecules of H2, which works out to about 11:1 (CO2:H2) by weight. That's a problem.
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Harvest 3:19PM (11/13/2007)
Jason #2
What they're referring to is the energy used to produce clean hydrogen gas versus the amount of energy stored chemically within the hydrogen produced.
The fact that they have found a way to use biologically assisted electrolysis to generate hydrogen that requires less energy than the hydrogen has in it is a really big deal.
This has been the fundamental problem with traditional electrolysis... the fact that it takes more energy to produce the hydrogen gas than can be generated by the hydrogen gas which is being produced.
This would be like a coal fired power plant that doesn't even produce enough energy to provide the required electricity to run the plant itself.
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Harvest 3:47PM (11/13/2007)
Lou #4
What's the link to that presentation, I wasn't able to find it.
Thanks!
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kagiso 4:12PM (11/13/2007)
The CO2 comes from vegetable matter, not fossil, so it is recently fixed CO2. The only source of fossil CO2 would be from the input electricity. If they used some of the hydrogen output in a fuel cell, to provide the current, then the net addition of CO2 to the atmosphere is zero.
And according to their figures you would still have net hydrogen coming out, with just waste vegetation as a feed stock. If this can be scaled up it would be very big indeed, much bigger than cellulosic ethanol.
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ug 4:24PM (11/13/2007)
"You get two molecules of CO2 for every 4 molecules of H2, which works out to about 11:1 (CO2:H2) by weight. That's a problem."
If the extra hydrogen output is due to the input of vinegar, and vinegar is a biological creation, wouldn't that be carbon neutral just like biodiesel?
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Joseph 8:13PM (11/13/2007)
The amount of energy that WE need to add is less than the amount of energy that comes out.
The amount of total energy that goes in (like from the bacteria or whatever) is always more than the energy that comes out. But we don't care about that energy the bacteria put out b/c we don't have to put in.
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Fabio 3:57AM (11/14/2007)
However, the bacterias need to take that energy from somewhere, and ultimately that source is the Sun.
Then why not use the Sun directly to produce electricity through the many means that exist to do so?
Moreover, what's efficiency are we talking about here? In an article on the same subject over at slashdot.com they say that the cited efficiency refers to the percentage of hydrogen in the processed compounds being released as free hydrogen, not the energy efficiency of the whole process.
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EEGeek 9:54AM (11/14/2007)
The Cheng & Logan paper in the Proceedings of the National Academy of Sciences is at http://www.pnas.org/cgi/reprint/0706379104v1.pdf
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Chris M 2:05AM (11/17/2007)
Correction: Bruce Logan and Shaoan Cheng of Penn State University may have devised a mechanism that can produce more hydrogen energy than the ELECTRICAL energy that must be added to the process.
There is additional chemical energy coming from the food needed by the bacteria. When that is figured in, the overall efficiency is around 80%, very good, but clearly it still follows the laws of thermodynamics. It actually works, unlike those imaginary "over-unity" devices.
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DasBoot 12:31AM (11/21/2007)
I fail to understand why it is important to get more energy out of the hydrogen than what is expended to create it.
While any form of fuel burned or reacted to create hydrogen makes the process of dubious environmental benefit, if pollution free solar energy is used for electrolysis, does it matter if it is only 50, or even 15% efficient?
Given the breakthroughs of companies like NanoSolar, that will reduce the cost of production and purchase price of solar panels drastically, does it not make the most sense to hydrolyze water and produce all the hydrogen we need without using any chemicals whatsoever? The simplest process may likely be the most practical one...
Imagine a house with an affordable solar roof, quietly producing hydrogen while the sun shines, storing it for later use in home and car fuel cells... Duh.
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Chris M 1:18AM (11/21/2007)
We can't get more energy out of hydrogen than what was expended to create it. However, efficiency is still important, especially when the source of that energy comes from expensive solar panels, and we are trying to reduce the use of fossil fuels to make electricity.
Even with this breakthrough, it is still twice as efficient to use batteries for electrical power storage, rather than H2. Also, H2 electrolyzers, H2 storage, and H2 fuel cells all cost more than the equivalent storage in LiIon batteries, and much more than equivalent lead acid batteries. Let's face it: Not many people can afford a half million dollar "H2 energy" system for their home.
BTW, all of the processes to produce H2 use "chemicals", you cannot produce Hydrogen without chemicals. Duh.
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Uncle B 7:22AM (4/14/2009)
As the desperation for cheaper fuel grows with OPEC and Saudi greed and Asian demands and their willingness to pay more for a larger share, Americans will find each power producing solution has an ideal niche - no one "silver bullet" solution for all situations - bio-diesel for distance transport, batteries for short hauls, Solar to feed huge new grids, Wind to supplement the same, Nuclear, one human error from Armageddon, reserved for military uses, its irreplaceable spot in the spectrum, and so on and so forth. Arguing the merits and disadvantages of each, though important, is an academic exercise, and must not be used to exclude possible energy systems. Tidal will come into play, as will georthermal and ground heat storage, and equally important, proper insulation at inception of buildings as well as solar heating and cooling considerations! Large factories will be located nearer their desert power sources, to prevent transmission losses, to a point of practicality, and all will be planned, and governed by the economics of the situation. There are no pat answers. We face a jumble of very complex issues requiring a large number of well educated minds to properly resolve. Ou schools are sadly lacking, while those of China are not! China has more post grad students with IQ's of 130+ than the U.S.A. has high school students, dropouts included! Obama has called for change, not for political gain, but for the desperate reality of survival in the 21st Century. America needs to get off of dope, booze, couches and lounge chairs and get moving or be eaten alive by the Asians! Every method here to produce power has merit, and must be exploited to the fullest, not critiqued into mediocrity. Show me "How I Can" not "Why it won't" Pseudo intellectualisms are ego-boosting, I admit, but suggestions that spur further though in this pool we call the net may inspire a solution to problems others are contemplating, and help resolve them for the common good. Let us not forget the great instrument of though communication we toy with, and grow to appreciate it for its great powers, The net!
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