The Center for Biofilm Engineering

CBE team designs and tests
microbial fuel cells

Engineering, Fall 2005

by Elizabeth Brock

__________________________________________ Imagine if you could drop a sensor in a stream, collect data from it and transfer the data via satellite connection to your laboratory for 10 years without returning to the site. Zbigniew Lewandowski, a civil engineer specializing in environmental engineering, and Haluk Beyenal, a chemical engineer, oversee a multidisciplinary team working to make this possible. Research funded by the Office of Naval Research at MSU’s Center for Biofilm Engineering is intended to confirm that such a scenario is possible using readily-available components.   Microbial fuel cells, devices that use catalytic reactions of microorganisms to convert chemical energy to electrical energy, play a key role in designing a “drop and forget” sensor. Because they have an unlimited supply of energy from reduced substances dissolved in water, and use

Raaja Raajan Angathevar Veluchamy (center), MS candidate in environmental engineering, measures the electrical power generated by a microbial fuel cell that the team operates in the lab while Haluk Beyenal (left) and Zbigniew Lewandowski (right) look on. (photo by Mike Nolop)

bacteria that exist in the water, they do not need to be replaced or recharged as traditional batteries do. They also can be used where data collectors that rely on solar energy are not practical.

Scientists have long known that biochemical reactions convert energy, but it is at the cutting edge to find practical ways to harness that energy. One obstacle to using that energy is that microbial fuel cells produce an infinite supply of sustained energy but very little power. To illustrate this dilemma, Lewandowski uses the known analogy of moving rocks. A person can use sustained energy to move a large pile of rocks one by one, but lacks the power to move the pile all at once. To activate the sensors, more power is needed than what can be created continuously.

To overcome these obstacles, Lewandowski and Beyenal have collaborated with computer scientists and electrical engineers. Electrical engineers found ways to convert sustained energy to short bursts of power needed to transmit the data, and U.S. Geological Survey experts helped the team use satellite technology to transmit data when it was found that antennas were too cumbersome.

Graduate students Allison Rhoads, Avinash Shantaram, Raaja Raajan Angathevar Veluchamy, Enrico Marsili and Joseph Menicucci have worked on the project, but ongoing support through the Undergraduate Scholars Program has also allowed undergraduates Conrad Donovan, Alan Weeden and Jake Wiggs to contribute. Students have become familiar with the tribulations of field research during the project. In one instance, the device was stolen from Roskie Creek when it was left overnight. In another instance, students gathering satellite data in Hyalite at midnight were questioned by police because of their “suspicious” behavior.

Environmental engineers are likely to find microbial fuel cells particularly useful. Alerting Homeland Security officials of a chemical attack on drinking water sources or measuring heavy metals in streams are among applications that researchers envision. In addition, the fuel cells themselves are environmentally friendly because they use naturally occurring bacteria and, in certain applications, eliminate the hazards of toxic chemicals that traditional batteries contain. Lewandowski predicts that advances in nanotechnology will make it possible to develop smaller devices that use less energy, further enhancing the practicality of using microbial fuel cells.