SILICON DESERT: Experiment turns waste into power

Tribune, The (Mesa, AZ) (KRT) Via Thomson Dialog NewsEdge) Mar. 27--Microorganisms 100 times smaller than the width of a human hair could help power America's energy future, a professor at Arizona State University says.

Bruce Rittmann, director of the Center for Environmental Biotechnology at the ASU Biodesign Institute, is experimenting with microbial fuel cells -- devices that use bacteria to produce electricity.

Weird though it may sound, some bacteria that feed on organic waste such as sewage, feedlot manure, algae or crop waste, release electrons in the process, creating an electric current, he said.

At the ASU lab, Rittmann and his research team have created bacteria biofilms that coat the electrodes in a fuel cell, setting up an electrical circuit between the anode and cathode.

"Someday, we could use this electricity to run a car," he said. "It also could be used eventually in a power plant."

Theoretically, biopower has a lot of advantages. It uses a renewable fuel supply. Also, unlike traditional combustion, the electricity production takes place at room temperature and no energy is lost as heat. And there are no combustionrelated pollutants to contribute to global warming. In fact, the only byproduct is ultra-pure water, Rittmann said.



Microbial fuel cells also have advantages over conventional fuel cells that run on hydrogen, Rittmann said.

For the most part, hydrogen is obtained from nonrenewable fossil fuels like coal and natural gas, which leaves them tied to the escalating cost of fossil fuels. Hydrogen can be extracted from water, but that consumes more energy than it produces, he said.

According to the U.S. Department of Energy, converting the energy value in domestic sewage to electricity could save the U.S. the equivalent of 2 million barrels of oil each year, while capturing the energy value of feedlot manure could save 6 million barrels a year.

But there still is a lot of work to do before microbial fuel cells will be churning out electricity for the local power grid.

So far, the process has only been accomplished on a small laboratory scale. And the rate that the bacteria produce electrons is about 1,000 times slower than in a conventional fuel cell.

"We're going to have to do a lot better if we're going to be competitive," Rittmann said. "A lot of the focus of our research is to understand why the rate is so slow, find the bottlenecks and make it go faster."

Also the cost of operating microbial fuel cells on a large scale is not yet known.

Rittmann's research is being funded partly by the National Aeronautics and Space Administration, which sees potential uses for microbial fuel cells on long-distance manned flights -- to Mars perhaps -- where they could recycle human, food and washing waste into electricity to run life-support systems.

An Arizona company, NZ Legacy, also is contributing money to the project. The company is interested in developing a large-scale prototype microbial fuel cell, Rittmann said.

OpenCEL, a Chicago-area company that has developed technology to pre-process biomass material, is also supporting the research.

"If we could put in a good effort on this, within five years we could have a modest prototype," Rittmann said.

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