Sustainable aviation fuel production using in-situ hydrogen supply via aqueous phase reforming: A techno-economic and life-cycle greenhouse gas emissions assessment

Sustainable aviation fuel (SAF) production is one of the strategies to guarantee an environmental-friendly development of the aviation sector. This work evaluates the technical, economic and environmental feasibility of obtaining SAFs by hydrogenation of vegetable oils thanks to in-situ hydrogen production via aqueous phase reforming (APR) of glycerol by-product. The novel implementation of APR would avoid the environmental burden of conventional fossil-derived hydrogen production, as well as intermittency and storage issues related to the use of RES-based (renewable energy sources) electrolysers. The conceptual design of a conventional and advanced (APR-aided) biorefinery was performed, considering a standard plant capacity equal to 180 ktonne/y of palm oil. For the advanced scenario, the feed underwent hydrolysis into glycerol and fatty acids; hence, the former was subjected to APR to provide hydrogen, which was further used in the hydrotreatment reactor where the fatty acids were deoxygenated. The techno-economic results showed that APR implementation led to a slight increase of the fixed capital investment by 6.6% compared to the conventional one, while direct manufacturing costs decreased by 22%. In order to get a 10% internal rate of return, the minimum fuel selling price was found equal to 1.84 $/kg, which is 17% lower than the one derived from conventional configurations (2.20 $/kg). The life-cycle GHG emission assessment showed that the carbon footprint of the advanced scenario was equal to ca. 12 g CO2/MJSAF, i.e., 54% lower than the conventional one (considering an energy-based allocation). The sensitivity analysis pointed out that the cost of the feedstock, SAF yield and the chosen plant size are keys pa-rameters for the marketability of this biorefinery, while the energy price has a negligible impact; moreover, the source of hydrogen has significant consequences on the environmental footprint of the plant. Finally, possible uncertainties for both scenarios were undertaken via Monte Carlo simulations.