With the global energy sector moving towards net zero emissions by 2050, biofuels and other renewable, clean energy sources have taken center stage. Now, researchers from the University of California, Riverside, have discovered a new method to make the most of wood and plant materials, turning them into sustainable liquid fuels and other products.
The newly developed chemical pretreatment can help cost-effective and carbon-neutral next-generation biofuel production.
The main focus of the study was on lignin (main component of plant cell walls). Ligning gives plants greater structural integrity and protection from microbes. This toughness has also made it difficult for scientists to extract and utilize plant matter or 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 in a release. “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.” He is the corresponding author of the research paper recently published in Energy & Environmental Science.
Lignin hurdle
Prof. Cai and his team developed a new method termed CELF (co-solvent enhanced lignocellulosic fractionation) for biomass pretreatment.
“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.”
The team notes that a CELF biorefinery can better utilize plant matter than the earlier methods.
Using poplar wood, which has higher carbon content, the team demonstrated the possibility of providing Sustainable Aviation Fuel to the market at prices as low as $3.15 per GGE (gallon of gasoline-equivalent). The current average cost for a gallon of jet fuel in the US is $5.96.
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“Spending a little more for a more carbon-rich feedstock like poplar still yields more economic benefits than a cheaper feedstock like corn stover because you can make more fuel and chemicals from it,” Cai said.
The paper details how lignin can be used to reduce the carbon footprint of biorefineries. “The older models would elect to burn the lignin to supplement heat and energy for these biorefineries because they could mostly only leverage the sugars in the biomass – a costly proposition that leaves a lot of value off the table,” said Cai.
Renewable chemicals production
“Adding tetrahydrofuran helps reduce the energy cost of pretreatment and helps isolate lignin, so you wouldn’t have to burn it anymore. On top of that, we can make renewable chemicals that help us achieve a near-zero global warming potential,” Cai said. “I think this moves the needle from Gen 2 biofuels to Gen 2+.”
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The Department of Energy’s Bioenergy Technology Office has now awarded the researchers a $2 million grant to build a small-scale CELF pilot plant at the university.
“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.”
