Agriculture has been a mainstay of the North Carolina economy for generations, but NC State researchers like Drs. Ratna Sharma and Mari Chinn are working to help farmers feed more than humans and animals. The two assistant professors in the Department of Biological and Agricultural Engineering are experimenting with crops and agricultural waste materials to develop new fuel sources that could feed the state’s economic growth by powering generators and vehicles.

Sharma uses microorganisms to begin breaking down cotton stalks before introducing enzymes to convert the cellulose in the woody plants into sugar, which is then fermented into ethanol. Because microbes are sometimes inefficient, she also works with chemicals, heat, and supercritical fluids—high-pressure gases that act as solvents—to find the best method to kick-start the process. “We are changing from a hydrocarbon to a carbohydrate economy,” she says, noting she also experiments with wheat straw, barley, sorghum, and switchgrass as feedstocks to create ethanol.

Chinn works with more traditional crops, like North Carolina sweet potatoes, to produce biofuels. She also is investigating a combination of fermentation with a gasification furnace as an alternative production method. Partial combustion of plant-derived feedstocks generates gases that Clostridium bacteria can convert into ethanol and acetate, Chinn says. The acetate currently limits ethanol yields, so she is refining the process to boost ethanol output. Sharma says tapping such resources, much of which would be cast aside as waste, could create enough alternative fuels to meet about half of U.S. needs. “You’re really getting something out of nothing.”

Read more about NC State research into biofuels and other energy technologies in the Summer 2006 issue of RESULTS.