Feasibility study on the use of hydrogen as an alternative fuel for conventional passenger aircraft

Aviation is at a turning point. To meet the 1.5-degree climate target, technological innovation is essential. Although recent advancements have partially decoupled air traffic growth from fuel consumption, projected growth rates of 3 to 5 percent render current measures insufficient. Cost-efficient and sustainable solutions are required – hydrogen offers such potential. This paper investigates the suitability of hydrogen as an alternative to fossil fuels, focusing on its integration into conventional tube-and-wing aircraft during the conceptual design phase, with an anticipated entry-into-service around 2035. Liquid hydrogen is stored in non-integral aluminum tanks located in the rear fuselage. Hydrogen-capable engines are assumed, with no further propulsion system analysis. Three existing aircraft types are selected as references and redesigned using a modular design tool, alongside a baseline variant that reflects future state-of-the-art developments in mass and efficiency. The hydrogen-powered variants retain the external geometry of the reference aircraft to ensure high commonality and retrofit potential, with a fuselage extension allowed for tank accommodation. Design methods follow standard handbook approaches, augmented by dedicated modules for hydrogen integration, particularly for tank sizing and placement, using manufacturer data as benchmarks. Initial results show that hydrogen-powered aircraft have higher operating empty masses due to tank mass but require less fuel mass. Environmentally, hydrogen aircraft eliminate CO2 and reduce NOx emissions, though increased water vapor emissions warrant further examination. Operational flexibility is slightly reduced compared to conventional aircraft. These findings highlight the feasibility and limitations of integrating hydrogen into existing aircraft configurations, offering a promising step toward sustainable aviation.