Microbial Fuel Cell – Energy From Wastewater?

By James Donahue

December 2004

Among the severe problems created by world overpopulation are excessive body waste and a shortage of clean and environmentally friendly energy for heating our homes and powering our machines.

Now an environmental engineer at Penn State University has dreamed up a possible way of using wastewater to generate a clean energy.

Bruce Logan says the device, dubbed a “microbial fuel cell,” is still experimental and is perhaps no more than a concept that seems to work.

The device involves two electrodes separated by a proton exchange membrane similar to that used in a conventional hydrogen fuel cell. “It opens the door to using existing hydrogen-gas-based stack technologies with bacteria in water,” Logan said.

He said wastewater flows on one side of the cell and air flows on the other, continuously generating electricity while also removing organic matter from the water.

The concept appears to be a workable solution to some energy problems, although Logan says he doesn’t see it solving all of the world’s needs.

Since the project began about two years ago, the technology has grown from a device that produces from 0.1 to 350 watts of energy per square meter of wastewater. “We’d like to get in the range of 500 to 1,000,” Logan said.

He said he doesn’t see his microbial fuel cell used for running cars or heating homes, but he believes it will be a useful power source on farm operations or at municipal waste treatment facilities where there is an abundance of organic material.

For example, Logan believes a wastewater treatment plant might power itself as it treats water. He also thinks it might produce a net amount of energy.

David Bagley, a scientist at University of Toronto, says the energy potential in wastewater is estimated at about 10 times the cost of treating it. “If we could achieve just one-twentieth of that power, we could break even,” he said.

Onward and upward.