In a world where the environmental impact of air travel continues to rise, a team of scientists at Washington State University (WSU) has made a significant breakthrough in jet fuel renowned as sustainable aviation fuel (SAF) production.
By developing a process to convert agricultural waste into jet fuel, their research brings the aviation industry one step closer to achieving carbon neutrality goals.
The study published in the journal *Fuel Processing Technology outlines a groundbreaking method to produce jet fuel using lignin, a structural molecule found in plant cell walls.
Lignin, which makes plants tough and woody, is typically found in corn stover—the stalks, cobs, and leaves left behind after a corn harvest—and other agricultural by-products. This innovative process could revolutionize the future of sustainable aviation by offering a greener, commercially viable alternative to fossil fuels.
A Continuous Process to Commercial Viability
One of the critical challenges for renewable fuels has been transitioning from theoretical research to scalable, real-world application. The WSU research team, led by Professor Bin Yang from the Department of Biological Systems Engineering, has taken a vital step in that direction by successfully testing a continuous production process for lignin-based jet fuel.
“Our achievement takes this technology one step closer to real-world use by providing data that lets us better gauge its feasibility for commercial aviation,” Yang explained.
The process developed by the team, called “simultaneous depolymerization and hydrodeoxygenation,” breaks down lignin polymers and removes oxygen in a single, continuous step. The outcome is a lignin-derived fuel that can be directly used in aviation, making it a promising candidate for sustainable jet fuel production. The team introduced dissolved lignin polymer into a continuous hydrotreating reactor at their Richland facility, marking the first time such a process has been successfully tested.
This continuous process represents a major leap toward the commercial-scale production of bio-based jet fuel, providing the aviation industry with a new tool to reduce its carbon footprint.
Tackling Aviation’s Carbon Footprint
The aviation industry’s demand for fuel is immense. In 2019, global consumption of aviation fuel reached a record high of nearly 100 billion gallons, with projections showing an increase in demand over the coming decades.
To meet global carbon neutrality goals, it is critical to develop and deploy SAFs that are both environmentally sustainable and compatible with existing aviation infrastructure.
The key to this research lies in the chemistry of lignin. While other forms of biofuel have focused on using bio-oil, the WSU team opted for a less processed and less expensive form of lignin, known as “technical lignin.” This material is derived from corn stover and represents a sustainable alternative to the extracted lignin bio-oils used in similar research.
A unique feature of lignin-based jet fuel is its ability to produce hydrocarbons that replace fossil fuel-derived aromatics. Aromatics, while essential in aviation fuel due to their density and seal-swelling characteristics, are associated with the formation of contrails and have significant climate impacts.
By replacing these compounds with lignin-derived cycloalkanes, the new fuel could reduce emissions while maintaining the fuel density needed for efficient jet engine performance.
Future of 100% Drop-In Sustainable Aviation Fuels
The ultimate goal of the aviation industry is to produce 100% renewable jet fuel that can be used without modifying existing aircraft engines or infrastructure. Lignin-based fuels could play a crucial role in this effort by increasing the density of fuel blends and serving as a “drop-in” fuel, meaning they could seamlessly replace traditional fossil-derived fuels.
Josh Heyne, a member of the WSU research team and co-director of the WSU-PNNL Bioproducts Institute, noted the significance of lignin-based fuel in complementing existing renewable fuel technologies.
“Lignin-based jet fuel complements existing technologies by, for example, increasing the density of fuel blends,” Heyne explained. This property could allow for smoother integration with conventional fuel systems, further driving the shift toward more sustainable aviation solutions.
A New Era for Aviation
The team’s work has been supported by key partners, including the U.S. Department of Energy’s Bioenergy Technologies Office, Pacific Northwest National Laboratory, the National Renewable Energy Laboratory, and Advanced Refining Technologies LLC.
With backing from such prestigious institutions, the WSU team is now focused on refining their process for greater efficiency and reduced costs, hoping to bring their technology closer to commercialization.
