US Dept. of Agriculture researchers are looking for electrochemically active bacteria that consume biomass sugars. Could this become a cost-effective way for producing hydrogen for fuel?

Here's the whole article from the USDA site
http://www.ars.usda.gov/is/pr/2007/071025.htm

Microbes Plus Sugars Equals Hydrogen Fuel?
By Jan Suszkiw
October 25, 2007
Wanted: Bacterium that can eat sugar or sludge; must be team player or electrochemically active; ability to survive without oxygen, a plus. Thus might read the bacterial "job description" posted by Agricultural Research Service (ARS) and Washington University (WU) scientists, who are collaborating on ways to make microbial fuel cells more efficient and practical.

According to Mike Cotta, who leads the ARS Fermentation Biotechnology Research Unit, Peoria, Ill., the project with WU arose from a mutual interest in developing sustainable methods of producing energy that could diminish U.S. reliance on crude oil.

Cotta's team specializes in using bacteria, yeasts or other microorganisms inside bioreactors to do work, such as ferment grain sugars into fuel ethanol. At WU in St. Louis, Mo., assistant professor Lars Angenent is investigating fuel cell systems that use mixtures of bacteria to treat organic wastewater and catalyze the release of electrons and protons, which then can be used to produce electricity or hydrogen fuel.

In September 2006, the researchers pooled their labs' resources and expertise to undertake a three-year cooperative project. One resource they'll share is the ARS Peoria-based Microbial Culture Collection, which houses about 87,000 accessions of freeze-dried microbes from around the world.

Using the collection's database information, the team is searching for microbes that "eat" biomass sugars (e.g., glucose and xylose from corn stover) and are electrochemically active. That means they can transfer electrons from fuel cell sugars without help from costly chemicals called mediators. The electrons, after traveling a circuit, combine with protons in a cathode chamber, forming hydrogen, which can be burned or converted into electricity.

Bacteroides and Shewanella are among bacteria species used to start the process.

Hydrogen's appeal stems from its natural abundance and capacity to store and release energy in a nonpolluting manner. The challenge is commercially producing it from sources other than fossil fuels, which are in limited supply and nonrenewable. About 95 percent of U.S. hydrogen comes from petroleum or natural gas via a process called steam reforming.

The link isn't working for me.

I'm not sure how they are going to use the bacteria's respiration as the anode... how are they going to connect and stay stable? Or did I read that wrong? I'm wondering how they are going to form the h2 when the protons are normally used to make ethanol (if it is glucose at the start).

edit: I was wrong, after looking at a dif. source they make h2 +2 as one of the other products in glycolysis.

Fixed the link, though it really doesn't provide much besides what was quoted. I'm also not knowledgable enough about the subject to speculate on unmentioned details. Although isn't it the purpose of the cathode chamber to produce the H2 using some type of catalyst?

I don't know if there would be a catalyst. I think adding electrons to protons produce H2 on it's own?

What I don't understand is how they are going to integrate a electrolysis device with the bacteria's complex, microscopic process of fermenting the sugars for energy. Assuming that is what they meant...

We need some bio experts in here! S.A.M., Spurious-Monkey, GeoffP, anyone? : o

I could not find details either; perhaps they want to patent it first?

Here is a picture of another experimental cell though

http://www.sciam.com/media/inline/000E4C95-A2CB-126E-A2CB83414B7F0000_1.gif

Bruce E. Logan and his colleagues at Penn State University modified a version of a microbial fuel cell (MFC) that they had conceived of to clean wastewater. "However," Logan explains, "to produce hydrogen, we keep oxygen out of the MFC and add a small amount of power into the system." By applying a boost of just 0.25 volt, the researchers succeeded in generating four times as much hydrogen as conventional fermentation does. What is more, the cell can be used with any biodegradable dissolved organic matter.


"While there is likely insufficient waste biomass to sustain a global hydrogen economy, this form of renewable energy production may help offset the substantial costs of wastewater treatment as well as provide a contribution to nations able to harness hydrogen as an energy source," Logan says. The results will be published in a forthcoming issue of the Journal of Environmental Science and Technology.
http://www.sciam.com/article.cfm?articleID=000E4C95-A2CB-126E-A2CB83414B7F0000

Using bacteria to create hydrogen or directly to use them in microbial fuel cells to generate electricity has basically one major problem:
The process is overall not very energy efficient.

It is driven by fermentation processes, however there are often several reactions at once. It depends on the bacteria present, as well as the carbon sources used what may happen. As these reactors are impossible to keep sterile it is quite hard to get the right bacterial population doing the right things, and even then it often costs too much energy to set up.
Typical reactions are for example butyrate or acetic acid fermentation:

hexose -> Acetic acid + 4H2
hexose -> butyric acid + 2H2

But in each case one would need to get hexoses as electron donor and similar limitations as to bio-ethanol apply here.

Another problem is that other bacteria present might degrade hexoses to alternative products (e.g. acetone/butanol/ethanol)
Or the H2 might get consumed, e.g. H2+CO2 -> acetic acid.

There is quite some research going to optimize the setup of a possible sustainable fermentation system.

The only functioning biogas system I am aware of are those involved in the production of methane instead of CO2, quite often found in agricultural complexes.

Regarding fuel cells, here the mechanism is different to hydrogen production.
Essentially the bacteria grow on the anodes. Essentially during respiration electrodes are transferred to a terminal electron acceptor. Under oxic conditions this is usually oxygen, but anaerobic bacteria can use a variety of other substrates including e.g. Fe(III), NO3 and so on. In the case of fuel cells the anode is used as electron acceptor.