Around 65% of the mitigation needed for the targeted net-zero carbon aviation emissions in 2050 is expected to come from Sustainable Aviation Fuels (SAFs). In this study, an alternative gasification-driven Biomass-to-Liquid (BtL) concept for the production of SAFs is introduced and evaluated. In particular, a fuel synthesis scheme based on the double-stage fermentation of the produced syngas (syngas → acetic acid → TAGs) is assessed instead of the conventional Fischer-Tropsch (FT) or Alcohol-to-Jet (AtJ) synthesis. The objective of the present work is the techno-economic evaluation of a large-scale (200 MWth) replication of the mentioned BtL concept, whose performance has been simulated in Aspen Plus^TM (V.11) with reasonable upscaling considerations and models validated at a pilot scale. The estimated baseline Total Capital Investment (TCI) of €577 million lies in the typical range of €500–700 million that many recent techno-economic studies adopt for gasification-driven BtL plants of similar capacity, while the estimated annual operating costs of €50 million correspond to a 15–40% OpEx reduction compared to such plants. A discounted cash flow analysis was carried out, and a baseline Minimum Jet Selling Price (MJSP) equal to 1.83 €/L was calculated, while a range of 1.38–2.27 €/L emerged from the sensitivity analysis. This study sets the biological conversion of gasification-derived syngas into triglycerides (TAGs) as a promising alternative route for the production of SAFs. In general, gasification-driven BtL pathways, led by the relatively mature FT and AtJ technologies, are capable of thriving in the coming years based on their capability of advanced feedstock flexibility.

Gas fermentation is gaining attention as a crucial technology for converting gaseous feedstocks into value-added chemicals. Despite numerous efforts over the past decade to investigate these innovative processes at a lab scale, to date, the evaluation of the technologies in relevant industrial environments is scarce. This study examines the fermentative production of acetate from biomass-derived syngas using Moorella thermoacetica. A mobile gas fermentation pilot plant was coupled to a bubbling fluidized-bed gasifier with syngas purification to convert crushed bark-derived syngas. The syngas purification steps included hot filtration, catalytic reforming, and final syngas cleaning. Different latter configurations were evaluated to enable a simplified syngas cleaning configuration for microbial syngas conversion compared to conventional catalytic synthesis. Fermentation tests using ultra-cleaned syngas showed comparable microbial growth (1.3 g/L) and acetate production (22.3 g/L) to the benchmark fermentation of synthetic gases (1.2 g/L of biomass and 25.2 g/L of acetate). Additional fermentation trials on partially purified syngas streams identified H₂S and HCN as the primary inhibitory compounds. They also indicated that caustic scrubbing is an adequate and simplified final gas cleaning step to facilitate extended microbial fermentation. Overall, this study shows the potential of gas fermentation to valorize crude gaseous feedstocks, such as industrial off-gases, into platform chemicals.