After three years of research, Gemma Reguera, assistant professor of microbiology and molecular genetics and of crop and soil sciences at Michigan State University, has developed a process that can be harnessed to produce clean, cheap electricity and fuel from plant biomass.
Microbial fuel cells are attracting interest as they are inexpensive to manufacture and produce no harmful by-products.
Using a specific selection of metal-reducing microorganisms in the Geobacter species – bacteria that are natural inhabitants of environments abundant in metals – Reguera was able to design a microbial fuel cell that acts as a natural battery to convert plant biomass into electrical power and produces a high yield, low-cost cellulosic ethanol product.
“Finding the exact match was difficult because there are billions of microbes living in the soil and water,” Reguera said. “By observing the natural processes of these organisms over time, we were able to reproduce these processes and develop a technology by matching up the right microbes.
“All the work of this process is done by bacteria inside a microbial fuel cell,” Reguera said. “Some of the bacteria decompose plant material while others move electrons to survive. The electron-moving microorganisms such as those in Geobacter naturally replace metal oxides with electrodes to get energy. This process is similar to how we breathe oxygen and exhale carbon dioxide.”
She said that producing ethanol is viewed as the main purpose, but having the fuel cell create electrical power as a by-product has added benefits. In the future, farms could be powered by their own plant by-products and fuel their own tractors from the same microbial fuel cell.
Making good matches between bacteria has yielded amazing results, but genetic manipulation could take the technology to a completely new level, Reguera said.
As part of her work with the Great Lakes Bioenergy Research Center, Reguera has modified a type of Geobacter to live in the same conditions as Cyanobacteria. Cyanobacteria are bacteria that produce energy from sunlight. The combination of these two types of bacteria means the fuel cells can produce electricity directly from sunlight.
Reguera’s next step is to make the fuel cells more efficient and successful at a larger scale. A team of Australian researchers is currently experimenting with microbial fuel cells to treat waste water effluent from a brewery while producing power. Microbial fuel cells are also being tested in ethanol biorefineries to remove toxic products from biomass pretreatments while generating ca. 25 percent of the electrical power needs of the biorefinery.
“I tell my students ‘you have to be very brave to be in my lab’ because they have to know how to do the entire process from the primary research to application,” Reguera said. “But they get really motivated when they see how small technologies can make huge impacts.”
Reguera’s work is funded by the Michigan Agricultural Experiment Station, the Rackham Fund Foundation and the Great Lakes Bioenergy Research Center - a partnership between MSU and the University of Wisconsin-Madison. The center is funded by the U.S. Department of Energy to conduct basic research aimed at solving some of the most complex problems in converting natural materials to energy.
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