An Integrated Approach for Optimization of Microbial Fuel Cells

PI: Daniel Bond (U. Minnesota)

Co-PIs: Raymond M. Hozalski and Tim LaPara (U. Minnesota)

Funding agency: Institute for Renewable Energy and the Environment

The recent discovery of the ability of bacteria to transfer electrons outside of their cytoplasm and onto solid surfaces such as electrodes has made it possible to use bacteria to produce electricity directly from waste organic material. In these “microbial fuel cells” (MFCs) bacteria act as self-assembling, self-regenerating biocatalysts able to oxidize diverse fuels and transfer electrons to an electrode. Unfortunately, our understanding of the fundamental aspects of MFCs, such as the mechanism(s) of electron transfer out of the cell to solid surfaces and of the interactions between electricity-producing cells and other bacteria in a mixed community, are very limited. Thus, our ability to improve the power output and efficiency of MFCs is severely inhibited, with current efforts largely relying on the trial-and-error approach. Through mathematical modeling and well-controlled experiments, our team is attempting to elucidate the fundamental molecular, microbiological, and mass transfer parameters that control electricity production in MFCs. Our specific aim is to define the microbiological and engineering parameters that limit electricity production by these bacteria, and address these issues to increase power output and efficiency.

Through mathematical modeling and well-controlled experiments, our team is attempting to elucidate the fundamental molecular, microbiological, and mass transfer parameters that control electricity production in MFCs. Our specific aim is to define the microbiological and engineering parameters that limit electricity production by these bacteria, and address these issues to increase power output and efficiency. Significant findings of our ongoing research to date include the following: (1) development of a comprehensive mathematic model of MFCs based on the fundamental processes of mass transfer, biodegradation, and electron transfer; (2) determination of the role of applied external resistance in MFC performance; and (3) extensive characterization of the electron transfer behavior of different strains of bacteria ( e.g. , Geobacter metallireducens , Shewanella putrafacens ) using fundamental electrochemical techniques such as cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy . One manuscript on the modeling work has been submitted to a peer-reviewed journal (Shimotori et al., Environmental Science & Technology , in review) and several more papers on our research are in preparation.