Emissions Comparison of 100% SAF With Bio-Aromatics and Conventional (Fossil) Jet Fuel

Abstract It is recognized that Sustainable Aviation Fuels (SAF) will play a significant role in the decarbonization of air mobility and various pathways and feedstocks are considered for their production. This may lead to differences in chemical and physical properties when compared to conventional, fossil, aviation fuel (CAF). SAF available today are blended with CAF and after blending they are compliant with the Jet Fuel norm (ASTM1655). But the goal of achieving 100% SAF could be problematic, as the absence of aromatics, one of the characteristics of SAF produced today, could lead to leaks in the seal. Adding renewable aromatics (Synthesized Aromatic Kerosene, or SAK) to the SAF is therefore seen as an opportunity to reach 100% SAF without impacting the aircraft and airport’s fuel infrastructures, potentially enabling a faster decarbonization of the sector. In this study, we have compared the emissions of a 100% SAF which contains 9% of SAK issued from the biomass (SAF-SPK/A) with a CAF. Performance and behavior: The tests did not identify any performance differences between the two fuels, including turbine reactivity and equipment degradation. This was later confirmed by Bell Helicopter during an experimental test flight campaign. Emissions: the lower CO2 impact is mainly due to the life cycle analysis of the SAF, but the test also showed reduced CO2 emissions during the combustion. While NO and NOx were found equivalent, significant reduction in CO and soot (Smoke Number, SN) were measured: −20 to −50% depending on the mass fuel flow. These improvements could be explained by the lower content of aromatics as well as the nature of these aromatics and this will be further investigated in future studies.