Life-Cycle Assessment of Power-to-Liquid Kerosene Produced from Renewable Electricity and CO2 from Direct Air Capture in Germany

Abstract

Decarbonization of the aviation sector is crucial to reaching the global climate targets. We quantified the environmental impacts of Power-to-Liquid kerosene produced via Fischer-Tropsch Synthesis from electricity and carbon dioxide from air as one broadly discussed alternative liquid jet fuel. We applied a life-cycle assessment considering a well-to-wake boundary for five impact categories including climate change and two inventory indicators. Three different electricity production mixes and four different kerosene production pathways in Germany were analyzed, including two Direct Air Capture technologies, and compared to fossil jet fuel. The environmental impacts of Power-to-Liquid kerosene varied significantly across the production pathways. E.g., when electricity from wind power was used, the reduction in CO2-eq. compared to fossil jet fuel varied between 27.6–46.2% (with non-CO2 effects) and between 52.6–88.9% (without non-CO2 effects). The reduction potential regarding CO2-eq. of the layout using low-temperature electrolysis and high-temperature Direct Air Capture was lower compared to the high-temperature electrolysis and low-temperature Direct Air Capture. Overall, the layout causing the lowest environmental impacts uses high-temperature electrolysis, low-temperature Direct Air Capture and electricity from wind power. This paper showed that PtL-kerosene produced with renewable energy could play an important role in decarbonizing the aviation sector.

Combining Fleetwide AviTeam Aviation Emission Modeling with LCA Perspectives for an Alternative Fuel Impact Assessment

“…Our results are closer to 40−70% reduced life cycle impacts for LH2 fuels from renewable electricity identified by Miller et al 30 and Dray et al 33 FP impacts in our study confirm previous results for FJF, 79 electrolysis, 88,89 and PtL production from renewable electricity sources. 18,23,48,90 As of today, results for LH2 and SPK are hypothetical as neither LH2 fuels nor SPK fuels have reached market readiness, given a low technological readiness, particularly for LH2 systems, and a significant cost premium of both alternative fuels compared to FJF. 11,32,33,91 This is a relevant source of uncertainty.…”

“…47 Systemwide studies integrating an LCA perspective of alternative aviation fuels are rare. Most LCA studies rely, if at all, on external sources for fleet properties like fuel burn and emissions (e.g., refs 19,23,31,48,49 ). Therefore, they tend to compare fuels on their energy values, thereby implicitly assuming that one MJ of FJF is equivalent to one MJ of LH2 fuel.…”

“…Miller et al 30 adjusted LH2 fuel demands with a fleetwide factor, however, without considering systemic variability such as extra fuel volume needs varying with flight distance. Previous well-to-wake (comprising FP and combustion) LCA studies report mitigation potentials in the GWP100 metric of 46−72% for PtL 19,23,48 and 40−99% for LH2 aviation fuels 30,31,49,50 when produced with renewable electricity. However, some of these studies do not quantify all the SLCFs 19,31,49 of aviation, and others 23,48 are not consistent with the International Panel on Climate Change (IPCC) Sixth Assessment Report climate functions for metrics calculation, 51 thus potentially underestimating the impacts of alternative fuels.…”

Sustainable Aviation Fuels for Clean Skies: Exploring the Potential and Perspectives of Strained Hydrocarbons

“…13,18 The power-to-liquid (PtL) pathway offers a promising alternative that addresses concerns related to land and food resources use in the production of SAF. Micheli et al 76 conducted a lifecycle assessment (LCA) of the PtL pathway and reported a significant reduction of −88.9% global warming potential (GWP) and −52.6% for GWP + radiative forcing index (RFI) compared to fossil fuel Jet A-1. This highlights the potential of PtL to substantially contribute to offsetting lifecycle GHG emissions.…”

“…This highlights the potential of PtL to substantially contribute to offsetting lifecycle GHG emissions. However, despite its considerable potential, the PtL pathway faces challenges such as high production costs and notable emissions, including 11.1% for GWP alone and 47.4% for GWP + RFI . These challenges necessitate mitigation strategies to achieve net-zero GHG emissions within the aviation sector.…”