Gaseous and Particulate Emissions from a Small Business Jet Using Conventional Jet A-1 and a 30% SAF Blend

Abstract

Small turbofan engines (<26.7 kN thrust) are unregulated for gaseous and particulate emissions, with emissions data largely absent from public databases. Yet, their environmental impact is likely increasing. This study examines emissions from a representative small turbofan engine on a Cessna Citation 560XL. It focuses on nonvolatile particulate matter (nvPM), gaseous pollutants, and volatile organic compounds (VOCs). Ground-level measurements were conducted using a standardized system with conventional Jet A-1 and a 30% blend of synthesized paraffinic kerosene from hydroprocessed esters and fatty acids (HEFA-SPK). This sustainable aviation fuel (SAF) blend reduced the nvPM mass and number emission indices (EIs) by ∼35% and ∼20% at idle, with diminishing effects at higher thrust. Estimated nvPM number EIs at cruise decreased by ∼10%, suggesting a similar reduction in contrail ice particle concentrations at the predicted nvPM number EIs. While CO, HC, and NOx emissions remained unchanged, SO2 emissions decreased proportionally to the fuel sulfur content. VOC analysis showed lower emissions of complex unsaturated hydrocarbons. These findings highlight SAF’s potential to mitigate climate and air quality impacts. They also reveal discrepancies in estimated emissions from small turbofan engines and underscore limitations in existing models that predict fuel composition effects on nvPM emissions.