Zero Emissions Flying Lab

The research aircraft Antares DLR-H2 is the first manned aircraft world-wide powered exclusively by fuel cells. It emits only pure water, rendering take-off, flight and landing CO₂ free and practically silent. The fuel cell drive unit converts hydrogen into electrical energy combustion-free through a direct electrochemical reaction with the oxygen in the air. “The powertrain with a combustion engine in a comparable application achieves only around 28 percent degree of efficiency, whereas the fuel cell achieves 43 percent”, says Head of Project Dr. Josef Kallo from the Institute of Technical Thermodynamics at the DLR site Stuttgart.

The DLR engineers work closely together with project partners from the industry, such as BASF Fuel Cells, Serenergy (Denmark) and Lange Research Aircraft GmbH, where the fuel cell aircraft Antares was built and re-equipped. With 460 kilograms, the basic aircraft Antares is a real light-weight. Two additional external freight containers for the fuel cell system and the hydrogen tank were attached underneath the wings that had to be strengthened for the purpose.

With the Antares DLR-H2, fuel cell systems for powering both the engines of small aeroplanes and the on-board power supply of large aircraft can be tested under real conditions. At the end of 2009, the fuel cell aircraft provided proof that the systems still work at altitudes of above 2,500 metres. “With the altitude record we could verify that the fuel cell flies efficiently and safely even under low pressure”, says Kallo. The fuel cell tests at pressure conditions similar to aviation conditions hitherto conducted at the Stuttgart laboratory hence could be verified during a real flight. “Yet a fuel cell drive unit would be unrealistic for passenger aircraft with their great load. However, their on-board power supply could be provided by a comparable system in future”, explains Kallo. Furthermore, a fuel cell based on-board power supply could also produce water, some 0.5 litres water per hour and per kilowatt output. In the course of a transatlantic flight, between 500 and 3,000 litres water could thus be produced and used, depending on the type of aircraft. As a result, less water has to be carried, so that weight and in turn fuel is reduced.