Life cycle CO2e intensity of power-to-liquid sustainable aviation fuel scenarios and specific use cases

The life cycle carbon dioxide equivalent (CO 2 e) intensity of Power-to-Liquid (PtL) sustainable aviation fuel (SAF) scenarios in Spain are evaluated using a specific, granular, and transparent modelling approach. Post combustion CO 2 capture and direct air CO 2 capture are considered, in addition to grid and renewable electricity sources. The mass and energy requirements of the PtL system are determined from a mass and energy conserved reaction mechanism and a comprehensive literature review. The SAF yield is constrained by its molecular composition, formulated to meet the physical property specifications for Fischer-Tropsch synthetic paraffinic kerosene (FT-SPK) in ASTM D7566 Annex 1. The results of the life cycle assessment (LCA) show large ranges in CO 2 e intensity of PtL SAF scenarios, from 11 to 101 gCO 2 e/MJ. The electricity emission factors at which the CO 2 e intensity of PtL SAFs meet the 70% reduction required under the ReFuelEU Aviation legislation are 112 – 168 gCO 2 e/kWh for direct air capture and post combustion capture of biogenic CO 2 . As the average EU grid is approximately 300 gCO 2 e/kWh, the use of renewable electricity (onsite or power purchase agreement) is therefore essential to achieve the 70% reduction. The carbon intensity of the Madrid to Dublin commercial flight route is analysed, per revenue-passenger-kilometre (RPK), as a specific use case with actual data of Ryanair Boeing 737-800 and 737 MAX 8 aircraft. Compared to the Science Based Targets 1.5°C limit of 3.3 gCO 2 /RPK, it is shown that sustainable aviation is challenging using PtL SAF, with a best case of 9 gCO 2 /RPK.