Influence of Power Split Ratio on Mass, Volume, and CO2 Emissions in Aircraft Electric Hybrid Propulsion Systems: A Multi-Criteria Decision-Making Approach

The aviation industry is undergoing a transformative shift toward more sustainable propulsion technologies, driven by the urgent need to reduce greenhouse gas emissions. As conventional propulsion faces increasing limitations in meeting long-term de-carbonization targets, the electrification of aircraft has received increasing attention, particularly for regional and short-haul aircraft. Within these systems, the distribution of power between on-board energy storage and power sources, commonly referred to as the power split ratio, has a significant impact on overall performance. This paper presents a quantitative investigation into how varying power split ratios affect the mass, volume, and carbon dioxide emissions of electric propulsion systems. A computational algorithm and Multi-Criteria Decision-Making (MCDM) method are applied to estimate the performance metrics of major components, using power density, energy density and efficiency as key parameters. The framework is applied to a case study of a 19-passenger commuter aircraft, demonstrating how component-level decisions propagate to system-level trade-offs. The results underscore the dominant influence of power supply and energy storage elements - battery, hydrogen (as energy carrier for fuel cell) and aviation kerosene - on mass, volume and CO₂ emissions of electric propulsion system, and provide guidance for choosing prioritized architectural concepts and operating points.