Abstract There is an urgent need to develop sustainable solutions for aviation to meet the climate targets set by the Paris Agreement. While some progress has been made in reducing in-flight emissions, current measures remain insufficient to achieve net-zero carbon emissions. A major challenge is developing sustainable powertrains that maintain aircraft performance, low mass, cost-efficiency, and safety standards. Hydrogen has emerged as a promising fuel, with various aviation concepts proposed. However, most concepts are not yet sufficiently advanced for commercial integration. This paper investigates the conceptual design and mass estimation of hydrogen-based powertrains and their integration into existing aircraft. Three powertrains are examined: hydrogen combustion engines, fuel cells, and hybrid systems combining both. All concepts use liquid hydrogen; kerosene-powered equivalents are assessed for comparison. A technology readiness level for market entry by 2035 is assumed. Due to the retrofit focus, integration options were limited. The required propulsive power, dependent on propulsion type and aircraft characteristics, was central to system sizing, which affected fuel consumption, tank design, and masses. An algorithmic approach using handbook methods and previous hydrogen tank studies was applied. Results show that hydrogen reduces fuel mass due to its low gravimetric density but increases operating empty mass due to tank and system mass. Hydrogen combustion yields a similar maximum take-off mass as kerosene. Fuel cell systems are infeasible due to high system mass. Hybrid configurations become viable above 50 percent fuel cell share but introduce added complexity and economic challenges. Nonetheless, the study supports hydrogen’s potential for zero-emission aviation.
Roscher et al. (Thu,) studied this question.
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