"People are looking at using cellulose to make ethanol," says Dr. Bruce E. Logan, the Kappe Professor of Environmental Engineering. "You can make ethanol from exploded corn stover, but once you have the sugars, you can make electricity directly."
Logan's process uses a microbial fuel cell to convert organic material into electricity. Previous work has shown that these fuel cells can generate electricity from glucose and from municipal wastewater and that these cells can also directly generate hydrogen gas.
Corn stalks and leaves, amassing 250 million tons a year, make up a third of the total solid waste produced in the United States. Currently, 90 percent of corn stover is left unused in the field. Corn stover is about 70 percent cellulose or hemicellulose, complex carbohydrates that are locked in chains. A steam explosion process releases the organic sugars and other compounds in the corn waste and these compounds can be fed to microbial fuel cells.
The microbial fuel cells contain two electrodes and anaerobic bacteria ?bacteria that do not need oxygen ?that consume the sugars and other organic material and release electrons. These electrons travel to the anode and flow in a wire to the cathode, producing electrical current. The water in the fuel cell donates positive hydrogen atoms that combine with the electrons and oxygen to form water.
The microbial fuel cells were inoculated with domestic wastewater and a nutrient medium containing glucose, the researchers report in the journal Energy and Fuels. Once established, the bacteria colonies were fed the sugary organic liquid obtained from steam exploding of corn stover.
The researchers, who include