To combat the challenges of breaking down lignocellulosic biomass in biofuel production, researchers at the University of California, Riverside have invented a novel pretreatment technology. The technique has the potential to cut the cost of biofuels production by about 30 percent or more by dramatically reducing the amount of enzymes needed to breakdown the raw materials that form biofuels.
The research group, led by Professor Charles Wyman, the Ford Motor Company Chair in Environmental Engineering at UC Riverside, has shown that this new operation, which is called Co-solvent Enhanced Lignocellulosic Fractionation (CELF), could eliminate about 90 percent of the enzymes needed for biological conversion of lignocellulosic biomass to fuels compared to prior practice. This development could mean reducing enzyme costs from about $1 per gallon of ethanol to about 10 cents or less.
How it works
The group’s published work shows 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.
In addition to such drastic cutting of the amount and cost of enzymes needed to realize nearly theoretical sugar yields, CELF is capable of dissolving and extracting up to 90 percent of the lignin in corn stover and even more for woody biomass. After pretreatment and enzymes release of the sugars from hemicellulose and cellulose, previous process strategies have focused on burning the residual lignin, which is a low value proposition. However, lignin has promise as a resource from which to make additional high value chemicals and fuels once it is extracted and depolymerized with CELF.