A new aviation fuel developed from agricultural waste could solve two pressing engineering challenges: sustainable air travel and hydrogen storage.
Washington State University (WSU) chemical engineers have created a method for transforming lignin, the rigid organic polymer that gives plants their rigidity, into a dual-purpose fuel that powers aircraft and stores hydrogen in a stable liquid form.
The WSU team, led by Professor Bin Yang, developed a continuous chemical process that breaks down lignin from corn stalks and other agricultural residues. Their method, known as simultaneous depolymerization and hydrodeoxygenation, converts these plant polymers into hydrocarbon molecules suitable for jet engines while maintaining the capability to bind hydrogen.
Bin Yang, professor in WSU’s Department of Biological Systems Engineering, stands with Andrew Lipton, scientist at Pacific Northwest National Laboratory, next to a nuclear magnetic resonance instrument used in experiments on new sustainable fuels. Image Credit: Andrea Starr and Eddie Pablo | Pacific Northwest National Laboratory
“We can now process lignin continuously, making it viable for commercial-scale production,” says Yang. The system employs specialized ruthenium catalysts that facilitate the breakdown of lignin’s complex molecular structure. This continuous process marks a significant advance over previous batch-processing methods, which were inefficient for large-scale fuel production.
The most interesting aspect of the fuel emerged during testing, though. The team discovered that their lignin-based fuel could chemically bind hydrogen in a stable liquid form, eliminating the need for pressurized storage tanks.
This characteristic addresses one of the main obstacles in hydrogen fuel adoption: the challenge of safely storing and transporting highly volatile hydrogen gas.
The binding mechanism works through chemical reactions that produce aromatic carbons, creating a stable medium for hydrogen storage. This dual functionality means the fuel can serve as a direct replacement for conventional jet fuel and as a hydrogen carrier, potentially transforming how we approach clean energy storage and transport.
Testing has demonstrated that the fuel maintains the critical properties required for aviation use. It provides appropriate energy density and preserves the sealing characteristics needed for aircraft engine operation. The fuel can be used as a direct replacement for existing aircraft engines, requiring no modifications to the current infrastructure.
The carbon yield currently stands at 17.9%, producing the specific types of cycloalkanes necessary for aviation fuel performance. These molecules ensure the fuel meets the stringent requirements for aircraft operation while offering improved environmental performance compared to conventional jet fuels.
The WSU team is now collaborating with scientists at the University of New Haven to develop artificial intelligence-driven catalysts. These advanced catalysts aim to enhance reaction efficiency and reduce processing costs, making the technology more commercially viable.
The research addresses growing industry demands for sustainable aviation fuel alternatives. With global aviation fuel consumption reaching nearly 100 billion gallons in 2019 and projected to increase by 32% by 2030, the need for sustainable alternatives has never been more pressing.
Despite the promising results, several engineering challenges must be addressed before widespread adoption becomes feasible.
The team continues to work on improving conversion rates and optimizing catalyst performance. Scaling production to commercial levels represents a significant engineering challenge that requires careful consideration of process efficiency and economic viability.
The research, funded by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy, represents a significant step toward sustainable aviation. While technical hurdles remain, this fuel system’s dual functionality offers a promising path forward for both aviation and hydrogen energy storage.
This technology could help create a more sustainable aviation industry while advancing hydrogen fuel infrastructure. The next development phase will focus on scaling the technology and optimizing the hydrogen storage and release mechanisms, bringing us closer to a future of cleaner air travel.
TLDR: WSU scientists have engineered a sustainable aviation fuel from agricultural waste that doubles as a hydrogen storage medium. Their continuous production transforms lignin into a fuel compatible with existing aircraft engines while safely storing hydrogen in liquid form, potentially advancing sustainable aviation and clean energy storage.
