Emissions and Energy Requirements of Current and Future Aircraft Operations

Abstract

Aviation faces significant challenges in achieving environmental objectives due to continued traffic growth and the complexity of reducing both CO2 and non-CO2 climate impacts. Existing aircraft performance and emissions assessments often rely on empirical modelling approaches and idealised design missions, limiting their applicability to future aircraft technologies and real-world airline operations. This thesis develops an integrated modelling framework that combines physics-based aircraft, propulsion, and combustion models with real-world airline operational data to enable robust, large-scale evaluation of aircraft energy use, emissions, and climate impacts. The framework coupled physics-based aerodynamic and propulsion system models with surrogate modelling techniques to achieve computational efficiency suitable for simulating complete airline operating schedules. Real-world operational fidelity was introduced through reconstruction of flight missions from airline data, capturing variability in mission range and operating conditions. The framework was applied to evaluate aviation decarbonisation pathways, with a particular focus on liquid hydrogen and synthetic sustainable aviation fuels, using a fleet-wide operational case study for a short-haul European airline. Comparative analyses of hydrogen-powered configurations highlighted the importance of accurate aircraft performance modelling when analysing prospective designs, while variation in results from off-design missions reinforced the need to account for real-world operational behaviour. As part of this modelling framework, physics-based methods for non-CO2 emissions were developed using chemical reactor network models to predict NOx, CO2, and H2O emissions as a function of engine operating condition. These models were integrated within the flight simulation framework and compared against conventional empirical approaches, demonstrating material differences in predicted emissions and associated climate impacts. The framework was further applied to assess the climate benefits of fleet renewal under realistic operational conditions, accounting for both near-term and long-term climate effects. The results show that fleet renewal can deliver substantial climate impact reductions, particularly for near-term warming, driven primarily by reductions in NOx emissions. In addition, pathways for extending the framework towards physics-based contrail formation modelling were demonstrated. The results demonstrate that operationally realistic, physics-based aircraft modelling can significantly alter the assessment of decarbonisation pathways and climate mitigation strategies compared to design-mission-based and empirical approaches. The modelling framework developed in this thesis provides a scalable and physically representative tool for evaluating future aircraft technologies, fuels, emissions, and fleet transition strategies under real-world operating conditions.