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[Display omitted] • Fischer-Tropsch pathway surpasses methanol pathway in total product efficiency. • Methanol pathway yields highest kerosene-related carbon and energy efficiency. • Methanol pathway shows thermodynamic advantages due to direct CO 2 conversion. • Chain growth probabilities above 90% favor Fischer-Tropsch pathway efficiencies. • MTO olefin selectivity mainly determines efficiencies of the methanol pathway. To achieve long-term greenhouse gas (GHG) neutrality within the aviation sector, substituting fossil aviation fuels with Sustainable Aviation Fuels (SAF) derived from renewable energy sources is essential. Among the synthetic SAF options produced through Power-to-Liquid (PtL) processes, the Fischer-Tropsch (FT) and methanol pathway are of significant interest. However, to assess and compare these pathways, detailed technical process analyses are required to provide a sound basis for economic and environmental assessments. Thus, this research paper investigates and compares both SAF production pathways starting from power-derived syngas within an in-depth technical analysis, providing novel insights into overall process characteristics and efficiencies. Carbon and energy flows are derived from steady-state flowsheet simulations. A variation of technical parameters (FT pathway: FT chain growth probability and hydrocracking behavior, Methanol pathway: Dehydration olefin-selectivity and oligomerization product distribution) is carried out to assess impacts on carbon and energy efficiency, indicating uncertainties and parameter ranges for optimized kerosene production. The results show a very high carbon efficiency of the FT pathway (98 to 99%) regarding the total liquid products, while the carbon efficiency regarding kerosene lies between 60 and 77%. For the methanol pathway, a higher kerosene carbon efficiency can be achieved (60 to 90%); however, the total product efficiency (74 to 92%) is notably lower. The energy efficiencies of both pathways behave similarly to carbon efficiency, with the methanol pathway benefiting from thermodynamic advantages, leading to higher energy efficiency at equal carbon efficiency. Within the FT pathway, kerosene efficiency increases at high chain growth probabilities, while a high olefin-selectivity is crucial for efficient kerosene production within the methanol pathway. The analysis results provide comprehensive insights into the technical behavior of the overall processes which contributes to an improved understanding of the production pathways. [ABSTRACT FROM AUTHOR]

[Display omitted] • Assessed concepts combine biogas- and electricity-based methanol production • Adding electricity-based hydrogen increases methanol production by 28 to 67% • Tri-reforming enables high biogas conversion for a total carbon utilization of 97% • Bi-reforming exceeds energy efficiency of tri-reforming by 5%pt. in overall concept • Methanol production costs are estimated at 1,300 € 2022 /t The limited potential of sustainably available biomass requires efficient conversion to defossilize future demands of carbon-based chemicals and energy carriers. Therefore, integrating electricity-derived hydrogen into biomass-based production concepts appears promising, maximizing carbon utilization while minimizing biomass requirement. However, specific process concepts and analyses are still lacking to quantify the potential technical and economic benefits of such hybrid production processes. Thus, this research paper investigates this novel approach for decentralized methanol production from biogas within a techno-economic analysis, considering two production configurations. One configuration (BiRef) utilizes electrically heated bi-reforming for syngas generation, while the other configuration (TriRef) uses autothermal tri-reforming. Based on stationary process simulations, in-depth knowledge about process behavior is gained, efficiencies and costs are determined, and influencing factors are assessed. Within the reference case, the BiRef configuration achieves a carbon efficiency of 93 %, while the TriRef configuration reaches 97 % due to its enhanced methane conversion. Energy efficiency is 5 %pt. higher within the BiRef configuration (74 %), primarily due to the lower hydrogen demand. Carbon and energy efficiency are crucially affected by reforming temperature and inert gas fraction in the syngas. The economic analysis shows methanol production costs of ca. 1,300 € 2022 /t for both configurations. Variations in economic parameters emphasize advantages for the TriRef configuration when low hydrogen costs (<6 € 2022 /kg) are achievable. The comparison with purely biogas-based methanol production shows that hydrogen addition increases production capacity by up to 67 %. Cost advantages result against purely electricity-based production, while cost parity is achieved with purely biogas-based production. This paper demonstrates the potential of hybrid methanol production for efficient biogas utilization and highlights decisive parameters influencing technical and economic efficiency. [ABSTRACT FROM AUTHOR]

• Biogenic feedstock is not sufficient to replace overall energy demand of aviation. • Non-biogenic feedstock is constrained by low capacities for renewably sourced energy. • Costs of the renewable aviation fuels are determined by feedstock and energy costs. • Synthetic kerosenes are options on a shorter, hydrogen rather on a longer timespan. The air transport sector's contribution to anthropogenic climate forcing is estimated at around 4 %. In this respect, alternative fuels are considered as a key measure to reduce greenhouse gas emissions within the air transport system and thus to reduce the contribution of commercial aviation to anthropogenic climate change. Nevertheless, so far the usage-shares of alternative fuels are below 1 %. Thus, the goal of this paper is to analyse a broad selection of aviation fuel options for their greenhouse gas reduction potential based on a set of nine assessment criteria. The fuel options studied are blended synthetic kerosene and neat synthetic kerosene fuels, three alcohols (methanol, ethanol and butanol) and three gases (methane, ammonia and hydrogen). For these fuels a multi-criteria assessment based on a five-step ordinal scale is performed. The assessment results show that the availability of some biogenic feedstock is not sufficient to replace the present overall energy demand of aviation; while the availability of non-biogenic fuels might increase in the near- to mid-term. In general, alternative kerosene-like fuel options are mainly constrained by lacking production capacities, while alcohols and gases considered are constrained by aircraft modifications or development of new aircraft types. All discussed fuel options have the potential to mitigate greenhouse gas emissions of commercial aviation substantially also from a life cycle perspective. Within the next decade, especially alternative kerosene-like options with (intermediate) products experiencing demand from other sectors, such as FT-SPK or AtJ-SPK, show a high development potential. The same holds for hydrogen provided that a hydrogen fueled aircraft will be brought successfully to the market. [ABSTRACT FROM AUTHOR]