The future technological potential of hydrogen fuel cell systems for aviation and preliminary co-design of a hybrid regional aircraft powertrain through a mathematical tool

The growing demand for air travel in the commercial sector leads to an increase in global emissions, whose mitigation entails transitioning from the current fossil-fuel based generation of aircrafts to a cleaner one within a short timeframe. The use of hydrogen and fuel cells has the potential to reach zero emissions in the aerospace sector, provided that required innovation and research efforts are substantially accomplished. Development programs, investments and new regulations are needed for this technology to be safe and economical. In this context, it makes sense to develop a model-based preliminary design methodology for a hybrid regional aircraft assisted by a battery hybridized fuel cell powertrain. The technological assumptions underlying the study refer to both current and expected data for 2035. The major contribution of the proposed methodology is to provide a mathematical tool that considers the interactions between the choice of components in terms of installed power and energy management. This simultaneous study is done because of the availability of versatile control maps. The tool was then deployed to define current and future technological scenarios for fuel cell, battery and hydrogen storage systems, by quickly adapting control strategies to different sizing criteria and technical specifications. In this way, it is possible to facilitate the estimation of the impact of different sizing criteria and technological features, at the aircraft level, on the onboard electrical system, the management of in-flight power, the propulsion methods, the impact of the masses on consumption and operational characteristics in a typical flight mission. The proposed combination of advanced sizing and energy management strategies allowed meeting mass and volume constraints with state-of-the-art PEM fuel cell and Li-ion battery specifications. Such a solution corresponds to a high degree of hybridization between the fuel cell system and battery pack (i.e., 300 kW and 750 kWh), whereas projected 2035 specs were demonstrated to help reduce mass and volume by 23 % and 40 %, respectively.