Sustainability assessment of alternative jet fuel for the U.S. Department of Defense

Abstract

Abstract The United States Department of Defense (DoD) is considering replacing the 2.8 billion gallons of petroleum jet fuel consumed within the continental United States (CONUS) annually with alternative jet fuels to reduce vulnerability to price and supply fluctuations and improve sustainability. We evaluate the feasibility of replacing DoD CONUS jet fuel with alternative jet fuel from domestic feedstocks and assess the cost, greenhouse gas (GHG) emissions, energy balance, land, water, and fertilizer impacts of nine alternative jet fuel pathways. The feedstocks include terrestrial crops (soy, corn, wood, and grass), marine microalgae, and by-products (forestry residue, municipal solid waste, and waste oil) converted by extraction, fermentation, or thermo-chemical conversion, paired with upgrading steps. We found that domestic biomass feedstocks can meet the DoD CONUS jet fuel demand without significantly affecting food supply. Alternative pathways cost more than petroleum jet fuel ($0.78\xa0l-1 and emitting 89\xa0g CO2 equivalent (CO2e) MJ−1), but many lowered GHG emissions. The forestry residue and waste oil pathways yielded the lowest costs ($0.92 and $0.82\xa0l-1, respectively), decreased emissions (23 and 35\xa0g CO2e MJ−1, respectively), and had negligible effects on land, water, and fertilizer resources. Tradeoffs among sustainability metrics are further explored with a sensitivity analysis and by evaluating carbon-cost scenarios.