Energy–environmental nexus in green hydrogen-assisted conversion of second-crop canola to sustainable aviation fuel: Toward low-carbon bioenergy systems

Aviation fuel remains the main cost and environmental burden in air transport. This study presents a well-to-wake life cycle assessment (LCA) of canola-based Sustainable Aviation Fuel (SAF) under tropical conditions, based on primary data from Brazilian producers. The analysis encompasses agricultural, pre-processing, and conversion stages via the hydroprocessed esters and fatty acids (HEFA) pathway, revealing the potential of second-crop canola for low-carbon aviation. The study integrates process modeling, renewable hydrogen, and land-use efficiency to capture drivers across stages. The ReCiPe method was applied to 1 MJ of biokerosene as the functional unit. Agriculture dominates GHG emissions (34.2 g CO 2 eq. MJ −1 ), driven primarily by fertilizer production and soil N 2 O emissions, while the HEFA phase contributes 12.8 g CO 2 eq. MJ −1 . Substituting fossil hydrogen with photovoltaic- and wind-based hydrogen for in HEFA upgrading reduces emissions by 92 to 96.6%, resulting in up to 19.6% lower total life-cycle emissions. Compared to Jet-A1, SAF decreases fossil depletion by 59% and achieves climate benefits; however, it entails higher burdens in selected non-climate impact categories. Freshwater and marine eutrophication reach approximately 0.01 g P eq. MJ −1 and 0.7 g N eq. MJ −1 , respectively, while human toxicity is above 1 g 1,4-DB eq. MJ −1 , with the agricultural stage accounting for over 90% of these impacts, particularly fertilizer production and use. Land occupation (0.074 m 2 yr MJ −1 ) is optimized through canola soybean rotation, mitigating deforestation risks. The findings demonstrate canola's strategic role in Brazil's decarbonization policies, highlighting the need for improved fertilizer management and renewable hydrogen integration to advance SAF.