The role of direct air capture in achieving climate-neutral aviation

Low-carbon fuels (LCFs) such as green hydrogen, synthetic hydrocarbons, and biofuels are critical for decarbonizing sectors that are difficult to electrify. In this study, we present a globally harmonized techno-economic assessment of 21 LCF production pathways, including power-to-X, biomass- and sun-to-liquids, and multiple hydrogen routes, evaluated across all countries under three future scenarios for 2024, 2030, and 2050. The model integrates spatially explicit resource data, learning-driven capital cost trajectories, and dynamic, country- and technology-specific costs of capital, supported by robust scenarios and uncertainty analysis. By 2050, median levelized costs are projected to range from 0.07 to 0.10 EUR2024 per kWh for green hydrogen, 0.15 to 0.18 EUR2024 per kWh for power-to-liquid kerosene, and 0.14 to 0.20 EUR2024 per kWh for most bio-based aviation fuels, reflecting both substantial progress and persistent regional disparities. Our results show that while innovation, technology learning, and deep power sector decarbonization can unlock cost-competitive electrofuels in countries with abundant renewables, bio-based routes are frequently cost competitive for sustainable aviation fuel (SAF) production in near-term scenarios, and solar-to-liquid fuels remain constrained by feedstock availability and capital barriers. Nuclear- and methane-based hydrogen emerge as primary options in many regions, as well as the dominance of turquoise hydrogen in Russia, the Middle East, and Central Asia where carbon management is viable, which highlights the context-specific nature of future LCF systems. We also found that the least-cost logistics for global hydrogen trade will shift from ammonia shipping to pipeline transport and methanol delivery, with North Africa and Iberia emerging as leading suppliers to Europe. These findings underscore the need for integrated innovation, policy coordination, and investment strategies that address both resource and financial barriers, in order to achieve scalable, resilient, and cost-effective LCF supply chains worldwide.

Transitioning the aviation sector to synthetic aviation fuels (SAF) requires innovative catalytic processes to overcome common limitations such as insufficient activity, selectivity, and catalyst deactivation. This study presents a detailed exploration of silica-supported phosphotungstic acid (PTA/SiO2) as a robust solid acid catalyst for propylene conversion into jet fuel-range hydrocarbons (C8 to C16) at mild reaction conditions (150 °C). The catalyst with optimized PTA loading (10 wt %) demonstrates significant oligomerization performance, achieving high selectivity to jet fuel-range hydrocarbons (>80%) and propylene conversion (>90%), alongside limited aromatic byproducts formation. Compared to conventional solid-acid catalysts such as a ZSM-5 zeolite, PTA/SiO2 exhibits significantly reduced catalyst deactivation and can be regenerated through mild thermal treatment (<400 °C). Detailed structural characterization revealed that PTA island size influences product selectivity. Increasing the PTA weight loading leads to larger active phase island sizes, with larger PTA islands preferentially producing longer-chain hydrocarbons (C15+). Raman spectroscopy confirms the preservation of the PTA Keggin structural integrity across all catalyst loadings, although perturbations in terminal W═O vibrations occur due to interactions with the SiO2 support. Crucially, insights obtained through combined XPS/HAXPES analyses reveal significant electronic interactions between PTA and SiO2, characterized by pronounced bending of the energy bands at the interface between semiconducting PTA and insulating SiO2. This effect generates interfacial tungsten states, which enhance localized electron mobility and facilitate proton transfer, significantly amplifying catalytic activity. Even catalysts with minimal Brønsted acidity (1 wt % PTA loading) exhibit notable turn over, emphasizing interfacial electronic modulation, rather than bulk acidity alone, as an important performance descriptor in olefin oligomerization.

An important step for moving forward in developing a sustainable fuel production: The SWEET Consortium reFuel.ch and the Port of Sohar and Freezone in Oman are joining forces for launching a research and production facility. Their commitment to collaborate in upscaling sustainable fuel production is marked by a letter of intent, signed at the Green Hydrogen Summit in Oman in December 2025.