Impact on contrails coverage when flying with hybrid electric aircraft

iation is responsible for approximately 5% of global warming and is expected to increase substantially in the future. In the face of the continuing expansion of air traffic, mitigation of the aviation’s climate impact becomes challenging, but imperative. Among various mitigation options, hybrid electric aircraft (HEA) has drawn intensive attention due to its large potential in reducing the greenhouse gas emissions. The non-CO2 effects (especially the contrails) of the HEA on the climate change, however, remains ambiguous. As the first step to understand the climate impact of HEA, this research aims to investigate the impact on the formation of persistent contrails when flying with HEA. The simulation is performed using the Earth System model (EMAC) coupled with a CONTRAIL submodel, where the Schmidt Appleman Criterion (SAC) is adapted to estimate changes in the potential contrail coverage (PCC) globally. The analysis shows that the HEA forms contrails at relatively lower temperature than conventional aircraft. At the same altitude, the reduction in contrails formation is mainly observed in the tropical regions where the temperature is warmer. With a smaller fraction of electric power in use, the contrail coverage remains nearly unchanged. As the degree of hybridization increases further to 90%, an exponential reduction in the contrail formation is expected with a maximum value of about 40%.Aircraft Noise and Climate Effect

Mitigating the Climate Impact from Aviation: Achievements and Results of the DLR WeCare Project

The WeCare project (Utilizing Weather information for Climate efficient and eco efficient future aviation), an internal project of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR), aimed at finding solutions for reducing the climate impact of aviation based on an improved understanding of the atmospheric impact from aviation by making use of measurements and modeling approaches. WeCare made some important contributions to advance the scientific understanding in the area of atmospheric and air transportation research. We characterize contrail properties, show that the aircraft type significantly influences these properties, and how contrail-cirrus interacts with natural cirrus. Aviation NOx emissions lead to ozone formation and we show that the strength of the ozone enhancement varies, depending on where within a weather pattern NOx is emitted. These results, in combination with results on the effects of aerosol emissions on low cloud properties, give a revised view on the total radiative forcing of aviation. The assessment of a fleet of strut-braced wing aircraft with an open rotor is investigated and reveals the potential to significantly reduce the climate impact. Intermediate stop operations have the potential to significantly reduce fuel consumption. However, we find that, if only optimized for fuel use, they will have an increased climate impact, since non-CO2 effects compensate the reduced warming from CO2 savings. Avoiding climate sensitive regions has a large potential in reducing climate impact at relatively low costs. Taking advantage of a full 3D optimization has a much better eco-efficiency than lateral re-routings, only. The implementation of such operational measures requires many more considerations. Non-CO2 aviation effects are not considered in international agreements. We showed that climate-optimal routing could be achieved, if market-based measures were in place, which include these non-CO2 effects. An alternative measure to foster climate-optimal routing is the closing of air spaces, which are very climate-sensitive. Although less effective than an unconstrained optimization with respect to climate, it still has a significant potential to reduce the climate impact of aviation. By combining atmospheric and air transportation research, we assess climate mitigation measures, aiming at providing information to aviation stakeholders and policy-makers to make aviation more climate compatible.Aircraft Noise and Climate Effect