Researchers at Washington State University (WSU) have successfully tested a groundbreaking method to produce sustainable jet fuel from lignin-based agricultural waste. This innovative research showcases a continuous process that transforms lignin polymers—key components of plant cells—into a jet fuel variant designed to enhance the performance of sustainably produced aviation fuels.
Lead scientist Bin Yang, a professor in WSU’s Department of Biological Systems Engineering, remarked, “Our achievement brings this technology closer to practical application by providing data that better assesses its feasibility for commercial aviation.”
Lignin, a class of structural molecules that gives plants their rigidity, is sourced from agricultural byproducts such as corn stover, which includes stalks, cobs, and leaves left over after harvest. The team developed a technique called “simultaneous depolymerization and hydrodeoxygenation.” This process not only breaks down the lignin polymer but also removes oxygen, resulting in lignin-based jet fuel. The researchers conducted their experiments at WSU’s Richland facility, where they introduced dissolved lignin polymer into a continuous hydrotreating reactor to produce the fuel.
With global aviation fuel consumption reaching nearly 100 billion gallons in 2019 and expected to rise in the coming years, sustainable aviation fuels derived from plant biomass offer a solution to reduce the aviation industry’s carbon footprint and help meet international carbon neutrality targets. Lignin-based jet fuel has the potential to enhance the cleanliness and usability of sustainable fuels in jet engines. Due to their density and efficiency, hydrocarbons derived from lignin could effectively replace fossil fuel-derived aromatic compounds, which are linked to contrails and climate change. Aromatics remain in use because they improve fuel density and swell O-rings in metal-to-metal joints.
This research marks the team’s first successful trial of a continuous process, which is more viable for commercial production. Notably, the project utilized a less processed, more affordable form of lignin derived from corn stover, referred to as “technical lignin,” rather than the extracted lignin bio-oil typically used in similar studies.
The team’s findings indicate that lignin represents a promising source of cycloalkanes and other valuable fuel compounds that could replace aromatics. “The aviation industry aims to achieve 100% renewable aviation fuel,” said Josh Heyne, a member of the research team and co-director of the WSU-PNNL Bioproducts Institute. “Lignin-based jet fuel complements existing technologies by enhancing the density of fuel blends.”
By offering reduced emissions, lignin-based fuel could eventually achieve full “drop-in” compatibility, meaning it can be utilized in all current engines, infrastructure, and aircraft, just like conventional fossil-derived aviation fuel.
“We’re focused on developing a commercially viable technology that serves as a complementary blend component to reach the 100% drop-in goal,” Heyne added.
This research received support from the U.S. Department of Energy’s Bioenergy Technologies Office, the Pacific Northwest National Laboratory, the National Renewable Energy Laboratory, and Advanced Refining Technologies LLC. The team is now working to optimize their process for improved efficiency and cost-effectiveness.
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