Climate Impact Reduction Potentials of Synthetic Kerosene and Green Hydrogen Powered Mid-Range Aircraft Concepts  
[PERSON]  
1 Deutsches Zentrum fur Luft- und Raumfahrt, Institut fur Systemarchitekturen in der Luftfahrt, 21129 Hamburg, Germany; [EMAIL_ADDRESS]  
2 Deutsches Zentrum fur Luft- und Raumfahrt, Institut fur Physik der Atmosphare, 82234 Oberpfaffenhofen, Germany; [EMAIL_ADDRESS]  
3 Deutsches Zentrum fur Luft- und Raumfahrt, Institut fur Antireibstechnik, 51147 Cologne, Germany; [EMAIL_ADDRESS]  
4 Deutsches Zentrum fur Luft- und Raumfahrt, Lufttransportsysteme, 21079 Hamburg, Germany; [EMAIL_ADDRESS]  
5 Deutsches Zentrum fur Luft- und Raumfahrt, Institut fur Verbrennungstechnik, 70569 Stuttgart, Germany; [EMAIL_ADDRESS]  
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multidisciplinary aircraft architecture and integration with the necessary level of detail, experts from all relevant fields participate in the study. That workflow includes detailed combustion chamber computations, complex engine performance modelling, a comprehensive overall aircraft design synthesis, and a surrogate climate chemistry response model applied on a defined global fleet scenario and route network, see Figure 1. The following CO\({}_{2}\) and non-CO\({}_{2}\) effects are taken into considerations as major climate impact contributors from aviation:  
* Direct CO\({}_{2}\) effects;
* Total NO\({}_{\text{x}}\) impact;
* Water vapour;
* Contrail induced cloudiness (CiC).  
CO\({}_{2}\) contributions can potentially be reduced by changing the energy carrier to renewable produced variants such as green hydrogen and synthetic fuel. Furthermore, a low-NO\({}_{\text{x}}\) and low-soot combustion chamber is utilized to strongly reduce the NO\({}_{\text{x}}\) effects. In addition to the change of the energy carrier and updated low-NO\({}_{\text{x}}\) technology options, the aircraft design was optimized for maximum contrail effect reductions by varying maximum operational altitudes and cruise Mach numbers. As flying lower and slower also comes with increased costs, the direct operating costs are calculated to balance the economic effects of the aforementioned concepts. Besides this specific climate impact reducing measures, the aircraft utilizes evolutionary efficiency improving technologies such as high bypass ratio geared turbofan engines and carbon fibre reinforced polymers (CFRP) as wing and empennage structural material.  
The investigated concepts are listed below:  
* D261: Reference based on B767-300.
* D261+: Baseline for entry into service (EIS) 2040 with evolutionary advancements and fossil kerosene.
* D261+DropIn: Similar to D261+, but designed and operated with 50% drop-in blend.
* D261+SAF: Similar to D261+, but designed and operated with 100% synthetic kerosene. An altitude constraint, cruise Mach number trade, is conducted.
* D261+H2: Same technological assumptions as D261+ but designed and operated with 100% green liquid hydrogen. An altitude constraint--cruise Mach number trade is conducted.  
All future concepts are designed with a conventional and advanced low-NO\({}_{\text{x}}\)/low-soot combustion technology. Furthermore, only the in-flight climate impact is considered, as the operation of commercial aircraft accounts for by far the biggest part of its life cycle. As it is assumed that the drop-in blend and the synthetic kerosene are produced with renewable carbon sources such as direct air capturing (DAC), the in-flight CO\({}_{2}\) emissions of these fuel portions do not cause any climate impact.