Paving the Way to Green Aviation: A Review of Sustainable Aviation Fuel Technologies, Properties, Emissions, and Future Directions

Aviation contributes approximately 4% to anthropogenic global warming, with passenger traffic anticipated to grow by 4.5% annually and CO 2 emissions projected to increase by 300–700% by 2050 without intervention. Conventional jet fuel (Jet A-1), a complex mixture of hydrocarbons, remains the primary energy source but produces unsustainable emissions due to its fossil origins. Sustainable aviation fuel (SAF) presents a promising alternative, potentially reducing emissions by up to 80% while being compatible with existing infrastructure and engines. This review examines the molecular structure of Jet A-1 as well as the six ASTM D7566-approved SAF pathways: Fischer–Tropsch synthetic paraffinic kerosene (FT-SPK), hydroprocessed esters and fatty acids (HEFA), alcohol-to-jet (ATJ), and synthesized iso-paraffins (SIP), catalytic hydrothermolysis jet (CHJ), and coprocessing, emphasizing the feedstock-to-fuel conversion process. It highlights the relationships among feedstock chemistry, catalytic processes, and the resulting hydrocarbon profiles, which affect key properties such as density, combustion heat, freezing point, and stability. Notably, HEFA is currently used commercially but is constrained by feedstock availability. Additionally, this paper examines cutting-edge propulsion options, including power-to-liquid, hydrogen, and battery technologies, and discusses the challenges and how they can be used with SAF in a sustainable way. Future focus areas include hybrid biochemical and electrochemical catalysis, AI-assisted molecular design, and the importance of policy support to meet the International Civil Aviation Organization’s (ICAO) net-zero emissions target by 2050. This review provides a comprehensive synthesis, addresses gaps in understanding the link between molecular properties and performance, and sets a roadmap for researchers, policymakers, and industry stakeholders.