The team from the Bourns College of Engineering Department of Chemical and Environmental Engineering and Center for Environmental Research and Technology (CE-CERT) shown that Co-solvent Enhanced Lignocellulosic Fractionation (CELF) could eliminate about 90% of the enzymes needed for conversion of lignocellulosic biomass to fuels.
Article continues below
This development could mean reducing enzyme 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..
Research by the Wyman team focuses on turning agricultural and forestry residues 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. 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 fermented 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 recalcitrance enough to realize the high yields vital to economic success.
The lignin left in biomass after most pretreatments presents a particular problem by impeding enzyme access to hemicellulose and cellulose, thereby hurting product yields and requiring more enzyme at a substantial cost.
CELF, the pretreatment developed at UC Riverside, solves those problems. In the ChemSusChem paper, the UC Riverside researchers outline laboratory results in which they compared the total achievable combined sugar yields between CELF pretreatment and dilute acid pretreatment, a current leading strategy, coupled with subsequent enzymatic hydrolysis in three timeframes with three levels of enzymes.
Using the dilute acid method, the sugar yield was only about 70 percent of the maximum possible after 14 days when two milligrams of enzymes were used. That percentage increased to about 85 percent in 14 days when 15 milligrams of enzymes were added.
By contrast, CELF pretreatment increased sugar yields to about 95 percent of the maximum possible regardless of whether two milligrams, five milligrams, or 15 milligrams of enzymes were added. Furthermore, the time required to reach these high yields dropped to five days when five milligrams of enzyme were used and two days when 15 milligrams of enzyme were used. ■
Under an intense surge of arctic air, Friday morning will begin with the coldest temperatures so far this season across much of the central and eastern U.S. with blustery conditions and a piercing wind chill.