Towards Net-Zero Sustainable Aviation Fuel with Wet Waste-Derived Volatile Fatty Acids

Nabila Huq, Glenn Hafenstine, Xiangchen Huo, Hannah Nguyen, Stephen Tifft, Davis Conklin, Daniela Stuck, Jim Stunkel, Zhibin Yang, Joshua Heyne, Matthew Wiatrowski, Yimin Zhang, Ling Tao, Junqing Zhu, Charles McEnally, Earl Christensen, Cameron Hays, Kurt Van Allsburg, Kinga Unocic, Harry Meyer IIIZia Abdullah, Derek Vardon

Research output: Contribution to journalArticlepeer-review

76 Scopus Citations

Abstract

With the increasing demand for net-zero sustainable aviation fuels (SAF), new conversion technologies are needed to process waste feedstocks and meet carbon reduction and cost targets. Wet waste is a low-cost, prevalent feedstock with the energy potential to displace over 20% of US jet fuel consumption; however, its complexity and high moisture typically relegates its use to methane production from anaerobic digestion. To overcome this, methanogenesis can be arrested during fermentation to instead produce C2 to C8 volatile fatty acids (VFA) for catalytic upgrading to SAF. Here, we evaluate the catalytic conversion of food waste–derived VFAs to produce n-paraffin SAF for near-term use as a 10 vol% blend for ASTM “Fast Track” qualification and produce a highly branched, isoparaffin VFA-SAF to increase the renewable blend limit. VFA ketonization models assessed the carbon chain length distributions suitable for each VFA-SAF conversion pathway, and food waste–derived VFA ketonization was demonstrated for >100 h of time on stream at approximately theoretical yield. Fuel property blending models and experimental testing determined normal paraffin VFA-SAF meets 10 vol% fuel specifications for “Fast Track.” Synergistic blending with isoparaffin VFA-SAF increased the blend limit to 70 vol% by addressing flashpoint and viscosity constraints, with sooting 34% lower than fossil jet. Techno-economic analysis evaluated the major catalytic process cost-drivers, determining the minimum fuel selling price as a function of VFA production costs. Life cycle analysis determined that if food waste is diverted from landfills to avoid methane emissions, VFA-SAF could enable up to 165% reduction in greenhouse gas emissions relative to fossil jet.

Original languageAmerican English
Article numbere2023008118
Number of pages11
JournalProceedings of the National Academy of Sciences of the United States of America
Volume118
Issue number13
DOIs
StatePublished - 30 Mar 2021

Bibliographical note

Publisher Copyright:
© 2021 National Academy of Sciences. All rights reserved.

NREL Publication Number

  • NREL/JA-5100-78354

Keywords

  • Biojet
  • Decarbonization
  • Food waste
  • Ketonization

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