UCR Associate Research Professor Charles Cai developed the CELF biomass pretreatment technology . ( Stan Lim / UCR )

By Jules Bernstein

When it comes to making fuel from plants , the first step has always been the hardest — breaking down the plant matter . A new study finds that introducing a simple , renewable chemical to the pretreatment step can finally make next-generation biofuel production both cost-effective and carbon neutral .

For biofuels to compete with petroleum , biorefinery operations must be designed to better utilize lignin . Lignin is one of the main components of plant cell walls . It provides plants with greater structural integrity and resiliency from microbial attacks . However , these natural properties of lignin also make it difficult to extract and utilize from the plant matter , also known as biomass .

“ 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 overcome the lignin hurdle , Cai invented CELF , which stands for co-solvent enhanced lignocellulosic fractionation . It is an innovative biomass pretreatment technology . “ 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 .”

A landmark Energy & Environmental Science paper details the degree to which a CELF biorefinery offers economic and environmental benefits over both petroleum-based fuels and earlier biofuel production methods .

The paper is a collaboration between Cai ’ s research team at UCR , the Center for Bioenergy Innovation managed by Oak Ridge National Laboratories , and the National Renewable Energy Laboratory , with funding provided by the U . S . Department of

Energy ’ s Office of Science . In it , the researchers consider two main variables : 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 like corn , soy , and sugarcane as raw materials , or feedstocks . Because these feedstocks can divert land and water away from food production , using them for biofuels is not ideal .

Second-generation operations use non-edible plant biomass as feedstocks . An example of biomass feedstocks includes wood residues from milling operations , sugarcane bagasse , or corn stover , all of which are abundant low-cost byproducts of forestry and agricultural operations .

According to the Department of Energy , up to a billion tons per year of biomass could be made available for the manufacture of biofuels and bioproducts in the US alone , capable of displacing 30 % of our petroleum consumption while also creating new domestic jobs .

Because a CELF biorefinery can more fully utilize plant matter than earlier second-generation methods , the researchers found that a heavier , denser feedstock like hardwood poplar is preferable over less carbon-dense corn stover for yielding greater economic and environmental benefits .

Using poplar in a CELF biorefinery , the researchers demonstrate that sustainable aviation fuel could be made at a break-even price as low as $ 3.15 per gallon of gasoline equivalent . The current average cost for a gallon of jet fuel in the U . S . is $ 5.96 .

The U . S . government issues credits for biofuel production in the form of renewable identification number credits , a subsidy meant to bolster domestic biofuel production . The tier of these credits issued for second-generation biofuels , the D3 tier , is typically traded at $ 1 per gallon or higher . At this price per credit , the paper demonstrates that one can expect a rate of return of over 20 % from the operation .

10 MARCH 2024 | FUEL OIL NEWS | www . fueloilnews . com