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Butler and Lovley Evaluate Strategies for Microbes Transforming Electrical Energy into Renewable Fuels and Other Commodities

Caitlyn Butler

Caitlyn Butler

The metabolic capabilities of microbes might very well offer a sustainable solution for transforming renewable electrical energy into green fuels and other biocommodities, according to an article co-authored by Assistant Professor Caitlyn Butler of the Civil and Environmental Engineering Department and Professor Derek Lovley of the Microbiology Department. Their featured article in the November 28 issue of Frontiers in Microbiology considered three promising strategies for biological production of carbon-based commodities with renewable electricity. Frontiers in Microbiology is the largest journal and second most cited journal in the field of microbiology, with an impact factor of 4.165. Read the article »

As the article noted, “Microbial metabolisms are a potentially sustainable mechanism for transforming renewable electrical energy into biocommodities that are easily stored and transported.”

The two authors stated that there is a mushrooming need for strategies to store or utilize the excess energy available whenever the production of renewable electricity exceeds demand.

According to their article, “A potentially sustainable biological solution would be to feed the electrical energy to a microbe that could either: (1) store the energy in a product that could later be efficiently converted back to electricity when demand was higher; or (2) produce a fuel that could replace fossil fuels; or (3) produce a commodity that otherwise would be made from non-renewable feedstocks such as petroleum.”

Butler and Lovley explained that acetogens and methanogens can reduce carbon dioxide to organic products, including methane, acetic acid, and ethanol. The library of biocommodities is expanded when engineered metabolisms of acetogens are included. Typically, electrochemical systems are employed to integrate renewable energy sources with biological systems for production of carbon-based commodities.

“Within these systems,” the article noted, “there are three prevailing mechanisms for delivering electrons to microorganisms for the conversion of carbon dioxide to reduce organic compounds: (1) electrons can be delivered to microorganisms via H2 produced separately in a electrolyzer; (2) H2 produced at a cathode can convey electrons to microorganisms supported on the cathode surface; and (3) a cathode can directly feed electrons to microorganisms.”

The authors concluded that each of these strategies has advantages and disadvantages that must be considered in designing full-scale processes.

“This review considers the evolving understanding of each of these approaches and the state of design for advancing these strategies toward viability,” said Butler and Lovley. The article then evaluated the three strategies in depth.

The original collaboration noted in the review was supported by a grant from the Advanced Research Projects Agency–Energy (ARPA-E) in the U. S. Department of Energy. Lovley’s microbial electrosynthesis research is currently supported by an Office of Naval Research grant.

Before coming to UMass, Butler was previously an assistant professor in the Department of Engineering at Arizona State University after receiving her Ph.D. from the University of Notre Dame in 2010. She currently works in the area of biofilm-based processes with an emphasis on resource recovery from waste streams. She and her collaborators have secured funding for these efforts from the Gates Foundation, the National Science Foundation CAREER Program, ARPA-E, and the Air Force Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) Programs. (December 2016)