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

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.