Blending Optimization for Synthetic Aviation Turbine Fuel: Pathways to 100% drop-in SATF

Kurzfassung

Currently, Sustainable Aviation Fuel (SAF) can only be used as jet fuel when blended with conventional fuels. There are eight different production pathways for synthetic blending components (SBC) with blending limits <50% defined in ASTM D7566 (Annexes A1-A8). Looking ahead, higher SAF blending limits will be needed, such as to meet the ReFuelEU’s target of using 70% SAF by 2050. In this context, an ASTM task force is proactively working on developing a specification for a 100%, fully formulated, 'drop‑in' SAF. This 100% ‘drop-in’ SAF can be obtained either by taking one of the SBCs from the D7566 pathways that has all the required chemical components and properties, or by blending two or more of them. To explore the huge design space available for 100% drop-in SAF while considering the complex relationship between composition and fuel properties, a multi-objective optimization framework has been developed using a Non-dominated Sorting Genetic Algorithm II (NSGA-II) and property prediction models. It has been used to generate blends of representatives of the D7566 pathways with optimized blending ratios, aiming for minimum sooting tendency and maximum density, while ensuring compliance with the expected 100% drop-in specification. The results in this case show an interplay between the preference for low viscosity fuels and those with higher cylcoalkanes and lower aromatics, which have the advantage of higher density and lower sooting tendency. The study also demonstrates the benefit of the optimization framework for producing blends targeting specific properties and specifications.