Researchers at the University of California, Riverside have invented a novel pretreatment technology that could cut the cost of biofuels production by about 30 percent or more by dramatically reducing the amount of enzymes² needed to breakdown³ the raw materials that form biofuels. As partners in the BioEnergy Science Center (BESC), the team from the Bourns College of Engineering Department of Chemical and Environmental Engineering and Center for Environmental Research and Technology (CE-CERT) have shown that this new operation called Co-solvent Enhanced Lignocellulosic Fractionation (CELF) could eliminate about 90 percent of the enzymes needed for biological conversion⁴ of lignocellulosic biomass to fuels compared to prior practice. This development could mean reducing enzyme¹ costs from about $1 per gallon of ethanol to about 10 cents or less.

 

The BioEnergy Science Center is a U.S. Department of Energy Bioenergy Research Center focused on enhancing science and technology to reduce the cost of biomass conversion through support by the Office of Biological and Environmental Research in the Department of Energy Office of Science..

 

"As recent months have shown, petroleum⁵ prices are inherently unstable⁶ and will likely return to high prices soon as expensive sources are taken off line," said Professor Charles Wyman, the Ford⁷ Motor Company Chair in Environmental Engineering at UC Riverside. "We have created a transformative technology that has the potential to make biofuels an economic sustainable alternative to petroleum-based fuels."

 

The findings by Wyman's research group were outlined in a just published paper, "Co-solvent Pretreatment Reduces Costly⁸ Enzyme Requirements for High Sugar and Ethanol Yields from Lignocellulosic Biomass," in the journal ChemSusChem. Co-authors with Wyman are: Thanh Yen⁹ Nguyen, Charles M. Cai, and Rajeev Kumar, all of whom are students or research engineers in Wyman's lab.

 

Research by the Wyman team focuses on turning agricultural and forestry¹⁰ residues¹¹ and other non-edible plant matter, known as lignocellulosic biomass, into liquid transportation fuels. Lignocellulosic biomass is attractive because it is sustainable and abundant and inexpensive compared to oil. For example, lignocellulosic biomass costing about $60?a dry ton is equivalent in unit energy costs to oil at about $20?barrel. (Oil is currently selling for about $55 a barrel but has hovered¹² around the $100 per barrel mark in recent years.) The challenge is to lower the cost of processing low cost biomass sources into fuels.

 

Lignocellulosic biomass is composed of hemicellulose, cellulose, and lignin, and biological processes favored for making liquid biofuels convert the hemicellulose and cellulose into sugars that can in turn be fermented¹³ into biofuels. However, the complex structure of lignocellulosic biomass makes it difficult for enzymes to release these sugars, and a pretreatment step using heat and chemicals is needed to reduce this recalcitrance¹⁴ enough to realize the high yields vital to economic success. The lignin left in biomass after most pretreatments presents a particular problem by impeding¹⁵ enzyme access to hemicellulose and cellulose, thereby¹⁶ hurting product yields and requiring more enzyme at a substantial cost.

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