Assessing the climate mitigation potential of targeted SAF use in 2030 at Copenhagen Airport

Abstract. Sustainable aviation fuels (SAFs) reduce CO₂ life-cycle emissions and the climate effect of contrail-induced cirrus cloudiness (CiC). In contrast to the CO₂ emissions of air traffic, the CiC climate effect varies strongly from flight to flight. Hence, SAF allocation to specific flights can maximise climate mitigation efforts for limited amounts of SAF, especially as long as SAF supply is meagre. In this study, we assess the climate-optimal SAF distribution for the flights departing from Copenhagen Airport (CPH) and determine the potential climate benefit achievable through this measure. The study particularly targets year 2030, when the 6 % SAF mandate by ReFuelEU Aviation is expected to allow large climate benefits through targeted SAF use and time still remains for infrastructural adaptions. For this, we use the AirClim model with a refined SAF parameterisation that considers non-volatile particulate matter (nvPM) reduction dependency on SAF blending ratio. We are allocating SAF to those flights that have the largest CiC climate effect to fuel use ratio in a climatological sense. In our scenario simulations, the additional climate benefit through targeted SAF use is quantified and the tradeoff between larger SAF blending ratios for less flights as a consequence of the limited SAF amount is analysed. Targeted use of the 6 % SAF can enhance the role of CiC regarding climate benefit of SAF from 20 % (uniform use) to almost 50 % (targeted use) when the optimal SAF blending ratio is chosen. In our results for CPH in 2030, this leads to a total additional reduction of 60 kt CO2e. However, the results show large uncertainties and strongly vary with choice of climate metric as well as with focus on long-term or short-term climate goals and depend on the specific flight plan. In addition, we quantify how much of the additional climate benefit would be sacrificed if a semi-optimal flight selection was chosen that potentially could reduce logistical cost by decreasing the number of SAF allocated flight routes. The results of this study set ground for cost-benefit analyses that take into account all airport operations associated with targeted SAF use at Copenhagen Airport.