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Directory:Penn State Microbial Fuel Cells Produce Hydrogen from Waste Water

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Page first featured November 13, 2007

Researchers have designed a microbial electrolysis cell in which bacteria break up acetic acid (a product of plant waste fermentation) to produce hydrogen gas with a very small electrical input from an outside source. Hydrogen can then be used for fuel cells or as a fuel additive in vehicles that now run on natural gas.Credit: Zina Deretsky, National Science Foundation.
Researchers have designed a microbial electrolysis cell in which bacteria break up acetic acid (a product of plant waste fermentation) to produce hydrogen gas with a very small electrical input from an outside source. Hydrogen can then be used for fuel cells or as a fuel additive in vehicles that now run on natural gas.
Credit: Zina Deretsky, National Science Foundation.

Aka : "BioElectrochemically Assisted Microbial Reactor" (BEAMR)


Microbial fuel cells (MFCs) represent a completely new method of renewable energy recovery: the direct conversion of organic matter (e.g. sewage waste) to electricity using bacteria. The method is highly efficient and produces a high volume of hydrogen.

A Penn State research group headed by Dr. Bruce Logan is working on developing MFCs that can generate electricity while accomplishing wastewater treatment.

Bacteria that feed on vinegar and waste water zapped with a shot of electricity could produce a clean hydrogen fuel to power vehicles that now run on petroleum. These microbial fuel cells can turn almost any biodegradable organic material into zero-emission hydrogen gas fuel.

The Penn State research group is now ready to begin the phase of demonstrating pilot-scale prototypes. It is yet too early to predice the price of this aparatus in commercial applications.

Contents

Microbial Fuel Cells

Official Websites



How it Works

"When bacteria are placed in the anode chamber of a specially-designed fuel cell that is free of oxygen, they attach to an electrode. Because they do not have oxygen, they must transfer the electrons that they obtain from consumption (oxidation) of their food somewhere else than to oxygen -- they transfer them to the electrode. In a MFC these electrons therefore go to the anode, while the counter electrode (the cathode) is exposed to oxygen. At the cathode the electrons, oxygen and protons combine to form only water. The two electrodes are at different potentials (about 0.5 V), creating a bio-battery (if the system is not refilled) or a fuel cell (if we constantly put in new food or "fuel" for the bacteria).

"By adding a small amount of voltage (0.25 V) to that produced at the anode in a MFC, and by not using oxygen at the cathode, you can produce pure hydrogen gas at the cathode! This is a modified MFC process we call the "bioelectrochemically assisted microbial reactor" or BEAMR process. This is a MFC operated in a completely anaerobic manner that uses the potential produced by bacteria, plus a small additional voltage (which could be produced by a MFC or other ways), that produces hydrogen through the recombination of protons and electrons at the cathode. Theoretically we need only 0.41 V to achieve this, so if the potential produced by bacteria could be increased (currently it is 0.3V), and the overpotential (losses) at the cathode reduced, we could one day produce hydrogen gas without additional voltage." [1]

Image:PennState MicrobialFuelCells 500.jpg
Microbial Fuel Cells at Penn State


The baceria function in a temperature window ranging from 20 to 30 degrees Celcius.

Rather than use specific bacteria and special chemicals, the Penn State method involves bacteria already present in wastewater.

In a commercial application, Dr. Logan envisions a tank with the bacteria digesting the incoming waste, producing hydrogen with just a small stimulus of electricity, then flowing out into a settling pond (trickling filter) and what emerges is water that has much less organic matter than came into the system.

History

The team began working with various mixtures for the soup. Over time they discovered that by changing the temperature, altering the ratio of water to the source materials, even adding a small amount of electricity, they were able to achieve efficiencies in excess of 90%. Using straight vinegar, for example, a 91% efficiency was achieved. Other materials provide 68% efficiency for raw, un-pretreated cellulose, 82% for lactic acid and acetic acid--both byproducts from normal fermentation. Glucose lags furthest behind, being only 64% efficient. [2]

Powerful return from input energy

The process produces 288% more energy than the electricity required to extract it. Compared to water hydrolysis, for example, which is only 50% to 70% efficient making it require more input energy than the extracted hydrogen yields, this process is far more desirable. It can be shown that even using enough of the harnessed energy to sustain the reaction, 144% more energy is produced. This makes the microbial soup solution a real application for energy generation. [3]

Farm benefits

The researchers indicate another possible use for these kinds of microbial cells is for manufacturing fertilizer. Instead of using current methods, which involve trucking in fertilizer made in factories, very large farms could begin using microbial cells. They would take wood chips processed through a common practice used today, along with nitrogen from the air, to produce ammonia or nitric acid. These can both be used as sources of fertilizer, or as feed material to make ammonium nitrate, sulfate or phosphate. [4]

Costs

Too early to say.

Patent

The research team has filed a patent for their discovery.

Profiles

Company: Ion Power Inc.

A scientist from Ion Power Inc is working with the Penn State researchers on this project. [5]

The Penn State work was funded by the National Science Foundation, as well as Air Products and Chemicals, Inc.

Inventor: Bruce E. Logan

Bruce Logan is Kappe professor of environmental engineering at Penn State, and an inventor of the MFC.

"Microbial Fuel Cells", by B.E. Logan is a new book on MFCs which will soon be published by John Wiley & Sons. (Email Dr. Logan if you are interested in purchasing a copy.)

See: http://www.engr.psu.edu/ce/ENVE/logan.htm

Coverage

Papers

  • New technique creates cheap, abundant hydrogen: report; The Proceedings of the National Academy of Sciences, AFP 12 Nov 07

In the News


  • New Fuel Cell Cleans Up Pollution And Produces Electricity Scientists in Pennsylvania are reporting development of a fuel cell that uses pollution from coal and metal mines to generate electricity, solving a serious environmental problem while providing a new source of energy. (Science Daily; Dec. 4, 2007)
  • Making Fuel from Leftovers - According to Penn State University researchers, feeding table scraps to bacteria may be a clean and efficient way to produce hydrogen that can be used as fuel. (MIT Technology Review]; Nov. 26, 2007)
  • Bacteria extract hydrogen at over 90% efficiency - By creating a type of controlled microbial soup out of materials straight from a salad bar, a bacteria-induced chemical reaction takes place, ultimately resulting in large quantities of hydrogen gas. (TG Daily; Nov. 14, 2007)

Other Coverage

Comments

See Discussion page

Contact

Bruce E. Logan
Kappe Professor of Environmental Engineering
231Q Sackett Bldg, Dept. of Civil and Environmental Engineering
The Pennsylvania State University, University Park, PA 16802
Phone: 814-863-7908, Fax: 814-863-7304

email: blogan@psu.edu

See also

HYDROGEN, GENERAL

HYDROGEN PRODUCTION AND STORAGE

HYDROGEN APPLICATIONS

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