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 language | English |
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Article number | e2023008118 |
Journal | Proceedings of the National Academy of Sciences of the United States of America |
Volume | 118 |
Issue number | 13 |
DOIs | |
State | Published - Mar 30 2021 |
Funding
We would like to acknowledge Cesar Granda and the employees of Earth Energy Renewables for providing VFA samples for catalytic upgrading. We thank S.K. Reeves for assistance with transmission electron microscopy sample preparation, Wilson McNeary for sulfur poisoning research and advising, Jacob Miller for catalyst testing experimental support, and Joel Miscall, Jon Luecke, and Gina Fioroni for valuable fuel property measurement and strategic discussions. We thank also Amma O. Kankam for sooting measurements and Lisa D. Pfefferle for useful discussion surrounding soot and emissions as well as Eric Karp for his review and feedback on VFA separations. A portion of this research was conducted as part of the Opportunities in Biojet Project sponsored by the US Department of Energy Office of Energy Efficiency and Renewable Energy and Bioenergy Technologies (BETO) and Vehicle Technologies Offices at the National Renewable Energy Laboratory (NREL) through Contract No. DE-AC36-08GO28308. A portion of this work was also conducted as part of the Chemical Catalysis for Bioenergy Consortium sponsored by BETO through Contract No. DE-AC36-08GO28308 at NREL. Diesel fuel property testing for VFA hydrocarbons was supported by the Co-Optimization of Fuels & Engines (Co-Optima) project sponsored by the US Department of Energy - Office of Energy Efficiency and Renewable Energy and BETO and Vehicle Technologies Offices at NREL through Contract No. DE347AC36-99GO10337. Microscopy was performed in collaboration with the Chemical Catalysis for Bioenergy Consortium under Contract No. DE-AC05-00OR22725 with Oak Ridge National Laboratory (ORNL) and through a user project supported by ORNL’s Center for Nanophase Materials Sciences, which is sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy. Part of the microscopy research was also supported by the Office of Nuclear Energy, Fuel Cycle Research & Development Program, and the Nuclear Science User Facilities. Work at the University of Dayton was supported by BETO through subcontract PO 2196073. Work at Yale was supported by the Co-Optima project sponsored by BETO through Contract No. DE-EE0008726. The views expressed in the article do not necessarily represent the views of the US Department of Energy or the US Government. The US Government retains and the publisher, by accepting the article for publication, acknowledges that the US Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for US Government purposes. ACKNOWLEDGMENTS. We would like to acknowledge Cesar Granda and the employees of Earth Energy Renewables for providing VFA samples for catalytic upgrading. We thank S.K. Reeves for assistance with transmission electron microscopy sample preparation, Wilson McNeary for sulfur poisoning research and advising, Jacob Miller for catalyst testing experimental support, and Joel Miscall, Jon Luecke, and Gina Fioroni for valuable fuel property measurement and strategic discussions. We thank also Amma O. Kankam for sooting measurements and Lisa D. Pfefferle for useful discussion surrounding soot and emissions as well as Eric Karp for his review and feedback on VFA separations. A portion of this research was conducted as part of the Opportunities in Biojet Project sponsored by the US Department of Energy Office of Energy Efficiency and Renewable Energy and Bioenergy Technologies (BETO) and Vehicle Technologies Offices at the National Renewable Energy Laboratory (NREL) through Contract No. DE-AC36-08GO28308. A portion of this work was also conducted as part of the Chemical Catalysis for Bioenergy Consortium sponsored by BETO through Contract No. DE-AC36-08GO28308 at NREL. Diesel fuel property testing for VFA hydrocarbons was supported by the Co-Optimization of Fuels & Engines (Co-Optima) project sponsored by the US Department of Energy - Office of Energy Efficiency and Renewable Energy and BETO and Vehicle Technologies Offices at NREL through Contract No. DE347AC36-99GO10337. Microscopy was performed in collaboration with the Chemical Catalysis for Bioenergy Consortium under Contract No. DE-AC05-00OR22725 with Oak Ridge National Laboratory (ORNL) and through a user project supported by ORNL’s Center for Nanophase Materials Sciences, which is sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy. Part of the microscopy research was also supported by the Office of Nuclear Energy, Fuel Cycle Research & Development Program, and the Nuclear Science User Facilities. Work at the University of Dayton was supported by BETO through subcontract PO 2196073. Work at Yale was supported by the Co-Optima project sponsored by BETO through Contract No. DE-EE0008726. The views expressed in the article do not necessarily represent the views of the US Department of Energy or the US Government. The US Government retains and the publisher, by accepting the article for publication, acknowledges that the US Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for US Government purposes.
Keywords
- Biojet
- Decarbonization
- Food waste
- Ketonization