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Urban air mobility (UAM) operations provide the potential for more, or more attractive, trips in a metropolitan area relative to wholly surface-based transportation. But the emissions produced by a UAM mode must be studied in relation to these benefits. In this paper, an emissions model for the UAM context using electric vertical takeoff and landing (eVTOL) aircraft is developed that incorporates CO2 gases emitted from the electricity production required to charge the vehicle batteries. The model quantifies trip emissions using UAM for part or all of the trip and compares these with automobile-based trips. The estimations consider using gasoline and electric automobiles, with the impact of autonomy and average ground speeds in traffic. Trip case studies in the Chicago and Dallas metropolitan areas showcase the regional differences when using UAM and different automobile technology scenarios. In particular, differences stemming from how electricity generation from power grids (i.e., grid emission index) contributes to CO2 emissions of eVTOL trips and electric automobile trips in the Chicago and Dallas metropolitan areas are computed. This paper introduces trip properties called the surface-to-air distance ratio and the detour ratio to understand how they influence the CO2 emissions of a trip. Results from the simulation on identified trip cases in Chicago and Dallas illustrate the significant impact of the grid emission index of a region’s power plant on the emissions of electric vehicles.

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This paper discusses a model of airlines' fleet planning decisions. In this model, aircraft retirement decisions are based on the net present value of potential new versus existing aircraft, and new aircraft acquisition decisions are based on the expected market demand to be satisfied in the future years. The model runs through three scenarios of passenger demand and aircraft technology evolution, and the results obtained show a comparison of effects of airline decision-making on their fleet composition and the environmental impact.