Fuel Cells for Aircraft Application

Although air transport is responsible for only about 2 % of all anthropogenic CO2 emissions, the rapidly increasing volume of air traffic leads to a general concern about the environmental impact of aircrafts. Future aircraft generations have to face enhanced requirements concerning productivity, environmental compatibility and higher operational availability, thus effecting technical, operational and economical aspects of in-flight and on-ground power generation systems. Today’s development in aircraft architecture undergoes a trend to a “more electric aircraft” which is characterised by a higher proportion of electrical systems substituting hydraulically or pneumatically driven components, and, thus, increasing the amount of electrical power. Fuel cell systems in this context represent a promising solution regarding the enhancement of the energy efficiency for both cruise and ground operations. For several years the Institute of Technical Thermodynamics of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR) in Stuttgart is engaged in the development of fuel cell systems for aircraft applications. In cooperation with Airbus several fuel cell applications within the aircraft for both ground and cruise operation were identified. In consequence fuel cell systems capable to support or even replace existing systems were derived. In this context, kerosene tank inertization and electrical cabin power supply including water regeneration represent the most promising application fields. The contribution will present the state of development discussing the following points: • Modeling of different system architectures and evaluation of promising fuel cell technologies (PEFC). • Experimental evaluation of fuel cell systems under relevant conditions (low-pressure, vibrations, reformate operation, etc.). • Fuel cell test in DLR`s research aircraft ATRA (A320) including the test of an emergency system based on hydrogen and oxygen with 20 Kilo Watts (kW) of electrical power and emission-free taxi ground operation with fuel cell system powering a nose wheel drive. DLR has developed the experimental motor glider Antares DLR H2 for testing of fuel cell technology under aviation conditions and for surveillance applications. The Antares DLR H2 is small, dismountable and has an experimental permit-to-fly. Thus both flight experiments and technical changes can be realized time- and cost-effectively. Equipped with fuel cell system, high power battery pack and all-electric drive train, the Antares DLR H2 is a flying test bench for fuel cells and fuel cell/battery hybrid systems. In September 2012 several long range flights have been successfully completed by this aircraft. In this context newly integrated low temperature fuel cell systems have been tested