Biofuel Breakthrough

Oak Ridge, Tenn. — Researchers at the Department of Energy’s BioEnergy Science Center have developed a new bioprocessing method combined with a biologically engineered microbe to create isobutanol directly from cellulose.

The work of the research team, headed by James Liao of the University of California at Los Angeles, represents an across-the-board savings in processing costs and time, plus isobutanol is a higher grade of alcohol than ethanol.

“Unlike ethanol, isobutanol can be blended at any ratio with gasoline and should eliminate the need for dedicated infrastructure in tanks or vehicles,” said Liao, chancellor’s professor and vice chair of Chemical and Biomolecular Engineering at the UCLA Henry Samueli School of Engineering and Applied Science. “Plus, it may be possible to use isobutanol directly in current engines without modification.”

Compared to ethanol, higher alcohols such as isobutanol are better candidates for gasoline replacement because they have an energy density, octane value and Reid vapor pressure – a measurement of volatility – that is much closer to gasoline, Liao said.

To make the conversion possible, Liao and postdoctoral researcher Wendy Higashide of UCLA and Yongchao Li and Yunfeng Yang of Oak Ridge National Laboratory, developed a strain of Clostridium cellulolyticum, a native cellulose-degrading microbe, that could synthesize isobutanol directly from cellulosic biomass like corn stover and switchgrass.

The paper, titled “Metabolic Engineering of Clostridium Cellulolyticum for Isobutanol Production from Cellulose,” is available online.
http://bioenergycenter.org