Table 1 Key aspects regarding the evaluation of climate impacts of aviation and their consideration in recent publications. “SAF” refers to drop-in hydrocarbon produced from hydrogen and CO2 via Fischer-Tropsch synthesis
Study | Net carbon intensity of SAF (including combustion and excluding non-CO2 climate impacts of combustion) | Approach for quantification of equivalence between CO2 and non-CO2 climate impacts due to short-lived climate forcers | SAF non-CO2 climate impacts | Consideration of radiative forcing beyond direct flight CO2 emissions and due to short-lived climate forcers | Consideration of radiative forcing of H2 emissions |
|---|---|---|---|---|---|
This study | Quantified using a Life Cycle Assessment (LCA) approach. | Linear-Warming-Equivalent (LWE) method. | Modeled according to syn-jet fuel properties (which leads to a reduction of radiative forcing). | Included; considering all short-lived greenhouse gases according to IPCC AR654 using an LCA approach. | Included; according to ref. 60 |
Brazzola et al.28 | Assumed to be zero. | GWP*. | Modeled according to syn-jet fuel properties (which leads to a reduction of radiative forcing). | Not included; lack of a complete LCA approach. | Not included. |
Klöwer et al.8 | Assumed to be zero. | Linear-Warming-Equivalent (LWE) method. | Only reduced contrail formation due to lower soot emissions considered. | Not included; lack of a complete LCA approach. | Not included. |
Grewe et al.29 | Generic assumption: Minus 65% net CO2 emission intensity compared to fossil kerosene in 2020, increasing to minus 80% in 2100. | Using the AirClim model106,107, the authors do not establish an equivalence between CO2 and SLCF. They calculate the effect on the climate of the various forcers using the simplified linear model AirClim. However, in Appendix B, they establish a simplified relationship between the forcing of CO2 and the forcing of O3—a simplified LWE method | Only reduced contrail formation due to lower soot emissions considered. | Not included; lack of a complete LCA approach. | Not included. |
Bergero et al.30 | Assumed to be zero. | GWP20/50/100, GTP20/50/100. | Assumed to be equal to those of fossil kerosene. | Not included; lack of a complete LCA approach. | Not included. |
Planès et al.31 | Generic assumption: Minus 75% net CO2 emission intensity. | GWP*. | Assumed to be equal to those of fossil kerosene. | Not included; lack of a complete LCA approach. | Not included. |
Dray et al.32 | Assumed to be zero. | GWP20/100/500. | Modeled according to syn-jet fuel properties (which leads to a reduction of radiative forcing). | Partially included: CO2, CH4, and N2O related climate impacts from fuel supply; lack of a complete LCA approach. | Not included. |
