Revolutionizing Biofuel Production: The Breakthrough of CELF Technology

One of the challenges facing the economically viable and carbon neutral production of advanced biofuels is the initial phase, where plant material is decomposed. Lignin, one of the main components of plant cell walls, provides plants with structural integrity and resiliency from microbial attacks, but also proves difficult to break down.

“Lignin utilization is the gateway to making what you want out of biomass in the most economical and environmentally friendly way possible,” said UC Riverside Associate Research Professor Charles Cai. “Designing a process that can better utilize both the lignin and sugars found in biomass is one of the most exciting technical challenges in this field.”

To address this problem, Cai invented an innovative biomass pretreatment technology called CELF – co-solvent enhanced lignocellulosic fractionation.

“CELF uses tetrahydrofuran or THF to supplement water and dilute acid during biomass pretreatment. It improves overall efficiency and adds lignin extraction capabilities,” Cai said. “Best of all, THF itself can be made from biomass sugars.”

Cai’s research team at UCR worked with the Center for Bioenergy Innovation managed by Oak Ridge National Laboratories, and the National Renewable Energy Laboratory to look at two factors in biofuel production: what kind of biomass is most ideal and what to do with the lignin once it’s been extracted. First-generation biofuel operations use food crops, so are not ideal. Second-generation operations use non-edible plant biomass as feedstocks, which are abundant low-cost byproducts of forestry and agricultural operations. As a CELF biorefinery can more fully utilize plant matter than earlier second-generation methods, they decided to test the use of poplar. They were able to demonstrate that sustainable aviation fuel could be made at a break-even price as low as $3.15 per gallon; the current average cost for a gallon of jet fuel in the U.S. is $5.96.

Due to CELF’s success, the Department of Energy’s Bioenergy Technology Office has awarded the team a $2 million grant to build a small-scale CELF pilot plant at UCR. Cai expects that demonstrating the pilot plant will lead to larger-scale investment in the technology.

“I began this work more than a decade ago because I wanted to make an impact. I wanted to find a viable alternative to fossil fuels and my colleagues and I have done that,” Cai said. “Using CELF, we have shown it is possible to create cost-effective fuels from biomass and lignin and help curb our contribution of carbon emissions into the atmosphere.”