Mass-based Optimization Studies for Sizing and Optimal Control of Hybrid Fuel Cell-Battery System for Commercial Airliners

The aviation industry currently accounts for nearly 1.7 billion tons of CO2 and non-CO2 emissions, which is projected to quadruple by the year 2050. In order to remediate these issues there exists an urgent need to decarbonize these sectors, for which batteries and fuel cell integrated systems are some alternative propulsion technologies currently being explored in the aviation sector. Integrating these systems however requires careful sizing and optimal control of the systems to minimize their mass, volume, or cost. In this study, a mass-based sizing and optimal control framework, using Dymos and OpenMDAO, was developed to size integrated fuel cell-battery systems for commercial airliners. It was used to optimize the mass of the powertrain system at provided constraints for the battery and fuel-cell systems, as well as operational power-profile requirements. An optimized split ratio for an integrated powertrain was also determined to define how to split the power between the fuel cell and the battery to meet the continuous power requirement profile. As a part of the study, optimization studies were performed for propulsion power time series of different short-, medium-, and long-haul airliners at multiple operating ranges with different gravimetric efficiencies of the hydrogen storage tank, specific powers of the fuel cell stack, and energy densities of the battery system. The study then presents a comparative analysis of the optimization results and discusses the suitability of the integrated powertrain system for different aircraft types and ranges in terms of take-off mass and retained passenger capacity. Initial results show that at lower operational range beyond 2 kW/kg of fuel cell stack specific power, the split ratios decrease with an increase in battery energy density. For the operational range of 900 NM, the split ratios decrease strongly with increase in battery energy density compared to lower operational range of 300 NM.

In AIAA SCITECH FORUM 2026