The Impact of Alternative Fuels on U.S. Domestic Aviation Emissions

The transition to alternative energy carriers offers a promising pathway to reduce the environmental footprint of aviation. This study investigates the impact of replacing conventional jet fuel with Liquid Hydrogen (LH2), Liquefied Petroleum Gas (LPG), and Liquefied Natural Gas (LNG) across five representative classes of transport aircraft operating within the U.S. domestic network. To isolate the effects of fuel utilization, the analysis assumes fixed aircraft weight and performance, and focuses on direct operational emissions. Mission simulations are performed utilizing RCAIDE, a multifidelity preliminary aircraft design framework, while emissions are estimated through a Chemical Reactor Network (CRN) model representing a Rich-Burn, Quick-Mix, Lean-Burn (RQL) combustor. The study captures operational trends for each aircraft-fuel combination and quantifies the influence of alternative fuel properties on combustor-level and mission-level emissions. Results reveal trends associated with each energy carrier and emphasize the role of their specific properties in shaping direct emissions at the fleet level. These findings aim to offer insights into the challenges and opportunities associated with integrating alternative fuels into the existing U.S. domestic aviation network.