Prospective life-cycle assessment of CORSIA sustainable aviation fuels under evolving electricity and hydrogen carbon intensities

Abstract

Most life-cycle assessments (LCAs) of alternative fuels evaluate electricity and hydrogen inputs using static or scenario-based carbon intensity assumptions. This study quantifies the impact of electricity and hydrogen on the life-cycle greenhouse gas (GHG) emissions of sustainable aviation fuels (SAFs). By coupling emission intensity projections for electricity grids and hydrogen production with Argonne National Laboratory's R&D GREET model, and following the life-cycle assessment (LCA) method of the International Civil Aviation Organization, we estimate life-cycle GHG emissions effects for two SAF pathways with comparatively high technology readiness levels: hydroprocessed esters and fatty acids (HEFA) from waste fats (tallow) and alcohol-to-jet (ATJ) from corn grain ethanol. Under the assumed trajectories for electricity grid decarbonization and hydrogen production carbon intensities, life-cycle GHG emissions of tallow HEFA and corn grain ATJ are estimated to be 7.7-12.5 gCO2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ extrm{gCO}_2$$\end{document}e/MJfuel lower in 2035 and 9.6-13.7 gCO2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ extrm{gCO}_2$$\end{document}e/MJfuel lower in 2050 relative to 2022 values. Additional facility-level mitigation measures, including carbon capture and waste heat utilization, could further reduce emissions per unit SAF. The work provides a prospective assessment by replacing static pathway intensities with a prospective LCA that couples SAF pathways to time-evolving electricity/hydrogen CIs and facility-level mitigation, quantifying dynamic GHG reductions to 2050. These findings underscore the importance of incorporating prospective energy system changes into SAF LCAs to more accurately capture future mitigation potential and inform effective aviation climate strategies.