Researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL), in partnership with the Massachusetts Institute of Technology and Washington State University, say they have developed a process that will unlock a heretofore unused but abundant feedstock for the production of sustainable aviation fuel (SAF).
While various plant matter has been used to produce biofuels, lignin—a tough fiber that makes up the cell walls—has been largely ignored as a possible feedstock due to the difficulties involved in breaking it down chemically. Oils derived from lignin have high oxygen content, making them unsuitable for use as a jet fuel feedstock where the oxygen content must be less than half a percent. The newly-published research, Continuous Hydrodeoxygenation of Lignin to Jet-Range Aromatic Hydrocarbons, describes the process used to remove oxygen from lignin, resulting in a product that can be used as jet fuel blendstock.
As well, SAF is limited to blending with conventional jet fuel due to the need for aromatics. Since lignin presents the largest source of renewable aromatics, the new process could pave the way for 100 percent SAF adoption.
The paper’s authors noted that in 2019, airlines consumed 106 billion gallons of jet fuel, an amount that is expected to double by 2050. To meet the carbon neutrality goals set for that timeframe, it will require a massive SAF production increase.