OAK RIDGE, Tenn., March 7, 2011 In the quest for inexpensive biofuels, cellulose proved no match for a bioprocessing strategy and genetically engineered microbe developed by researchers at the Department of Energy's BioEnergy Science Center.
Using consolidated bioprocessing, a team led by James Liao of the University of California at Los Angeles for the first time produced isobutanol directly from cellulose. The team's work, published online in Applied and Environmental Microbiology, represents 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.
While cellulosic biomass like corn stover and switchgrass is abundant and cheap, it is much more difficult to utilize than corn and sugar cane. This is due in large part because of recalcitrance, or a plant's natural defenses to being chemically dismantled.
Adding to the complexity is the fact biofuel production that involves several steps pretreatment, enzyme treatment and fermentation is more costly than a method that combines biomass utilization and the fermentation of sugars to biofuel into a single process.
To make the conversion possible, Liao and postdoctoral researcher Wendy Higashide of UCLA and Yongchao Li and Yunfeng Yang of Oak Ridge National Labo
|Contact: Ron Walli|
DOE/Oak Ridge National Laboratory