SGER: Bio-Electrochemical Energy Conversion Processes

CBET-0834033

Regan

Exoelectrogenic microbes, which can respire and conserve energy using extracellular electron acceptors, are important biocatalysts in natural environments whose metabolism can be also employed in a number of beneficial applications, including the direct conversion of chemical energy into electrical energy in microbial fuel cells (MFCs). Until recently, power generated by MFCs was limited by high internal resistance caused by physical and chemical constraints. Improvements in system architecture have recently begun to expose microbial kinetic constraints on performance. Recent work by our group provides conclusive evidence of a limiting role of the anode biofilm. A thorough understanding of the charge transport in these structures is the key to achieving future performance breakthroughs. Fundamental understanding is needed on the kinetics of electrochemical and biochemical reactions for different mechanisms of electron transport by the bacteria, factors influencing biofilm growth, and the impact of biofilm properties on bio-electrochemical transport processes.

The goal of this project is to converge microbial, electrochemical, and transport characterizations to reveal and mechanistically describe the relationship between biofilm ecology and MFC performance. To achieve this, we propose to test the following three hypotheses: (1) the catalyst density in an anode biofilm affects system performance in a time-varying manner that can be described in a more fundamental way, (2) the catalyst density in an anode biofilm is a predictable function of the applied external resistance, and (3) the microbial mechanism of extracellular electron transfer to the anode affects the maximum power capabilities of a microbial culture.

Intellectual Merit: Successful completion of the proposed research will enable dramatic advancements in MFC technology, as the biocatalytic activity has emerged as the limiting feature of MFCs but has received little attention. This project will offer important contributions to multiple fields, including energy production from renewable sources, environmental and agricultural engineering through bioremediation of organic wastes, oceanography by serving as energy sources for undersea sensors, and biogeochemistry in the area of mineral reduction and the associated implications in the carbon cycle and nutrient availability. Broader Impacts: Advancements in MFC technology can revolutionize renewable energy production and waste treatment. Understanding MFC microbial ecology and engineering this ecology to increase power generation are necessary for the realization of this potential. The research plan will foster the interdisciplinary training of engineers in microbiological, molecular, and electrochemical techniques, allowing a broader preparation for careers in the inherently and increasingly interdisciplinary field of energy production.