Hybrid fuel cell power in aircraft

Traditionally, electric generators, driven by an aircraft's main propulsion engines or by a gas turbine (GT) auxiliary power unit (APU), have supplied the electrical needs of commercial aircraft. In flight, the marginal efficiency of electric power generated by the main engines and their generators is at most 30-40%, whereas on the ground with the engines shut off, the average fuel efficiency of the turbine-powered APU is typically less than 20% and also has undesirable noise and gaseous emissions. As environmental concerns mount, aircraft manufacturers and others are challenged to reduce fuel consumption while simultaneously reducing emissions. Hence, there is a very strong interest in developing fuel cells for aerospace applications. In this article, we report the study results of usingsolid oxide fuel cells (SOFCs) in combination with a GTas a hybrid APU system for a commercial aircraft. The purpose of this feasibility study is to investigate the potential use of fuel-cell-based APUs for onboard power generation in future "more-electric" commercial aircraft. In this article, the modeling of the major components of the SOFC-GT power generation system, summary of the findings, challenges, and final recommendations are presented.