Air traffic has a considerable contribution to climate change via CO2 and non-CO2 climate drivers, such as nitrogen oxides and aviation induced cloudiness. The global climate impact from air traffic varies not only with the amount and type of emitted species, but also with altitude, latitude of emission and the ambient atmospheric conditions. The assessment of options to reduce the climate impact from aviation by new aircraft designs, technologies and operations requires expert knowledge from different disciplines and adequate models that sufficiently incorporate the driving impact factors. Air traffic has a considerable contribution to climate change via CO2 and non-CO2 climate drivers, such as nitrogen oxides and aviation induced cloudiness. The global climate impact from air traffic varies not only with the amount and type of emitted species, but also with altitude, latitude of emission and the ambient atmospheric conditions. The assessment of options to reduce the climate impact from aviation by new aircraft designs, technologies and operations requires expert knowledge from different disciplines and adequate models that sufficiently incorporate the driving impact factors. Such a comprehensive simulation and analysis approach was developed within the DLR project Climate compatible Air Transport System (CATS) from 2008 to 2012. The goal of CATS is to provide a sound assessment of operational and technological options to reduce the climate impact of air traffic. Such a comprehensive simulation and analysis approach was developed within the DLR project Climate compatible Air Transport System (CATS) from 2008 to 2012. The goal of CATS is to provide a sound assessment of operational and technological options to reduce the climate impact of air traffic.
Therefore, a multidisciplinary simulation workflow was developed with the contribution of several DLR institutions and under the lead of DLR Institute of Atmospheric Physics and DLR Air Transportation Systems. The CATS simulation workflow integrates physics based models for aircraft design, engine performance, aircraft subsystems, trajectory calculation, cosmic radiation exposure, direct operating costs and climate impact. All models are linked via the standardized data format CPACS in the simulation framework RCE-Chameleon, both developed by DLR and available open source. The integrated climate response model is specifically designed for aviation climate impact studies and considers the impacts of CO2, H2O, CH4, O3 and primary ozone mode (PMO) (latter three resulting from NOx emissions), line-shaped contrails and contrails cirrus clouds as function of altitude and latitude of emission. These impacts are based on a linearization of atmospheric processes computed with a full climate-chemistry model and include the temporal evolution of emissions, atmospheric concentration changes and resulting radiative forcing and near surface temperature changes. The developed simulation chain is applied to analyse the climate impact mitigation potential and related costs resulting from the combined optimization of flight profile and aircraft characteristics. The assessment includes the world fleets of a current representative long-range aircraft and a novel climate-optimized aircraft configuration that are operated on a global route network.
The average near surface temperature change and cash operating costs are computed for numerous combinations of cruise altitude and speed on each route in the network. Based on this, the route-specific Pareto optimal cruise conditions that maximize the ratio of climate impact reduction vs. cost penalty are derived. The resulting mitigation potentials are expressed relative to a realistic traffic scenario and flight profiles derived from Eurocontrol CFMU data.The study shows a considerable potential for current aircraft to reduce the climate impact of aviation at small to moderate cost penalties, e.g. a 42% reduction of near surface temperature change for a 10% cost penalty. However, it also shows that current aircraft suffer performance losses and related fuel burn penalties when being operated in off-design conditions at lower cruise altitudes. Optimizing current aircraft for cruise conditions with reduced climate impact allows a further improvement of the mitigation potential in combination with a reduction of the resulting cost penalty. Through the combination of flight profile and aircraft optimization it is for example possible to reduce the climate impact by 32% without increase of cash operating costs.
Involved partner institutions