The European Union guides its member states to a gradual uptake of sustainable aviation fuel (SAF) from 2% vol. in 2025 to 63% vol. by 2050 with the ReFuelEU proposal as part of the Fit-for-55 package. A promising production pathway for SAF presents itself in the Power Biomass to Liquid (PBtL) process, which converts non-crop-based biomass residue and renewable power via the Fischer–Tropsch route. In this study, a techno-economic and greenhouse gas (GHG) emission analysis of a small-scale (50 MWth) PBtL process concept, developed in the EU project FLEXCHX, is presented. The analysis is conducted with a thermodynamic process model implemented in Aspen Plus®, which relies on experimental project data. For the PBtL base case production costs of 1.09 €2020/l are estimated, whereby electricity and investment into the alkaline electrolyzer constitute the largest cost drivers. At low electricity prices (< 39.2 €/MWh), the PBtL process is more cost effective than the reference process Biomass to Liquid (BtL). To identify improvements to the base case design, different design options are considered under varying economic boundary conditions: Solid oxide electrolysis is more economic than alkaline electrolysis at higher electricity prices due to its higher system efficiency. Maximizing the product yield by increased CO2 recycling is only economically reasonable below an electricity price threshold, which is found at 20 €/MWh for the base case. Further, PBtL is heavily dependent upon the availability of low GHG electricity in order to produce SAF with a low carbon footprint. Assuming full utilization of the EU’s non-crop-based biomass residues, the EU jet fuel demand for 2030 could be met with the PBtL process.

Different processes have been proposed to meet the global need for renewable fuel. The Biomass to Liquid process (BtL) converts biomass via the Fischer-Tropsch route to hydrocarbon chains that can be refined to transport fuel. With the addition of electrolytic hydrogen to the Power and Biomass to Liquid process (PBtL), the carbon efficiency can be increased relative to the BtL process. It was shown in previous studies that the PBtL concept has an economic edge over BtL when cheap electricity is available to maximize the fuel yield. In this study, a techno-economic analysis is conducted for a hybrid process concept which can switch operation modes from electrolysis enhanced to only biomass conversion. In case studies the effect of the Fischer-Tropsch conversion, H2/CO ratio of the Fischer-Tropsch feed and the biomass feed rate in the electrolysis enhanced mode are analyzed. Every process configuration is modeled based on experimentally validated unit models from literature in the commercial software Aspen Plus and analyzed using DLR’s software tool TEPET. For a 200 MWth biomass input plant, production costs of 1.08 €2019/L for the hybrid concept with a carbon efficiency of 53.3% compared to 0.66 €2019/L for BtL with 35.4% and 1 €2019/L for PBtL with 61.1% were found based on the Finnish day-ahead market for the base case. The net production cost for the hybrid concept can be decreased by 0.07 €2019/L when a Fischer-Tropsch H2/CO ratio of 1.6 instead of 2.05 is used.

Sustainable aviation fuels provide the opportunity to reduce the climate impact of air transport while avoiding a complete overhaul of the existing fleet. For Europe, the domestic production of sustainable...

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