According to recent research, experimental plant-based jet fuel could enhance engine performance and efficacy, while dispensing with aromatics — the pollution-causing compounds seen in traditional fuels.
A Pacific Northwest National Laboratory scientist at Richland, Wash., helps develop a sustainable fuel component as part of research into bio-based jet fuels. Image Credit: Washington State University.
Researchers examined a jet fuel created by Washington State University that is based on lignin, an organic polymer that tends to make plants tough and woody. The study was published in the journal Fuel.
The researchers analyzed fuel properties important to jet engine operation, such as density, seal swell, efficiency and emissions, using a variety of tests and predictions. Their findings suggest that this environmentally friendly fuel could be blended with other biofuels to completely replace petroleum-based fuels.
When we tested our lignin jet fuel, we saw some interesting results. We found that it not only had increased energy density and content but also could totally replace aromatics, which are a real problem for the aviation industry.
Bin Yang, Study Corresponding Author and Professor, Department of Biological Systems Engineering, Washington State University
Joshua Heyne (co-author, University of Dayton scientist, and current co-director of the joint WSU-PNNL Bioproducts Institute) states, “Aromatics are associated with increased soot emissions, as well as contrails, which are estimated to contribute more to the climate impact of aviation than carbon dioxide.”
Aromatics are still used in fuel today because we do not have solutions to some of the problems they solve: they provide jet fuel with a density that other sustainable technologies do not. Most unique is their ability to swell the O-rings used to seal metal-to-metal joints, and they do this well.
Joshua Heyne, Study Co-Author and Scientist, University of Dayton
Heyne adds, “We want to fly safely, sustainably, and with the lowest impact to human health. The question is, how do we do all of this as economically as possible?”
Yang created a patented method for converting agricultural waste lignin into bio-based lignin jet fuel. This type of environmentally friendly fuel could help the aviation industry reduce its reliance on exorbitantly expensive fossil fuels while also meeting stricter environmental standards.
According to the researchers, the WSU-developed, lignin-based fuel’s properties “offer great opportunities for increasing fuel performance, higher fuel efficiency, reduced emission, and lower costs.”
They added, “The fact that these molecules show sealant volume swell comparable with aromatics opens the door to develop jet fuels with virtually no aromatics, very low emissions, and very high-performance characteristics.”
The lignin-based fuel we tested complements other sustainable aviation fuels by increasing the density and, perhaps most importantly, the ring-swelling potential of blends. While meeting our material needs, these sustainable blends confer higher energy densities and specific energies without using aromatics.
Joshua Heyne, Study Co-Author and Scientist, University of Dayton
Yang remarks, “This process creates a cleaner, more energy-dense fuel. That’s exactly what sustainable aviation fuels need for the future.”
Zhibin Yang, University of Dayton; Zhangyang Xu and Maoqi Feng, WSU; John Cort, Pacific Northwest National Laboratory; and Rafal Gieleciak, Natural Resources Canada also contributed to the study.
The research was supported by Defense Advanced Research Projects Agency through the US Department of Defense, the US Department of Energy’s Office of Energy Efficiency & Renewable Energy, the National Science Foundation, the US Department of Transportation’s Sun Grant Initiative, and the National Renewable Laboratory.
The Joint Center for Aerospace Technology Innovation, and WSU’s Bioproducts, Science and Engineering Laboratory also supported Yang and his team’s research.
Journal Reference:
Yang, Z., et al. (2022) Lignin-based jet fuel and its blending effect with conventional jet fuel. Fuel. doi.org/10.1016/j.fuel.2022.124040.