Hydrogen for aviation

Fuel cell propulsion systems are not only being developed for unmanned aircraft, hydrogen is also increasingly becoming a topic in passenger transport.

In 2018, the Element One project was launched to transport four passengers over distances of 500 to 5,000 km, ©
HES Energy Systems, Singapore

Fuel cell propulsion systems are not only being developed for unmanned aircraft, hydrogen is also increasingly becoming a topic in passenger transport. The US space agency NASA, for example, together with the engineering school of the University of Illinois, is constructing electric aircraft using liquid hydrogen and fuel cells.

On the one hand, the cryogenic fuel can facilitate the cooling of the units, but on the other hand, the insulation of the cryogenic containers still poses a challenge.

In the Netherlands there is the prototype of a two-seater H2 motor glider, which the student team AeroDelf of TU Delft presented at the beginning of May 2019. Also with this Phoenix project there are space problems, because the insulation of the LH2 tanks in itself is 20 cm thick.

Henri Werij from the Faculty of Aeronautics and Astronautics at Delft Technical University reported that the principle of laminar boundary layer extraction was used here in order to be able to fly as energy-efficiently as possible. The wings have been fitted with 14 million tiny holes to reduce air resistance by up to 15%. The first test flight of a small prototype is scheduled for 7 September 2019.

China, on the other hand, is more advanced. Commercial Aircraft Corp. announced that its Lingque H (LQ-H2) hydrogen-powered aircraft has now completed ten test flights in Zhengzhou, Henan Province. COMAC developed the new aircraft with a wingspan of six metres together with State Grid, Gree (Shenzhen) and the Institute of Aeronautical Science and Mechanical Engineering at Beihang University.

Fuel cells for on-board energy supply

Parallel to such efforts in the field of drive technology, work will continue on fuel cell-powered auxiliary power units in the aviation sector. In the USA, for example, Liebherr Aerospace & Transportation and General Motors (GM) are researching a fuel cell to replace the auxiliary gas turbine (APU) in the next generation of aircraft. The first step of the project is the construction of a demonstrator. Nicolas Bonleux, head of sales at Liebherr Aerospace & Transportation, said Aerobuzz: “At some airports, it is no longer permitted to use the APU.” Fuel cells are more efficient here and also have lower emissions than turbines (less noise, less exhaust gases). For this reason, a system demonstrator is currently being developed that is to be integrated into an aircraft, just as the German Aerospace Center (DLR) and Airbus did more than ten years ago (see HZwei issue July 2008).

At that time, in July 2007, the first flight tests were carried out, with the help of which the function of the fuel cell was tested under aviation-relevant conditions and successfully demonstrated. Following on from this work, Airbus is still active in this field today and was awarded the German Aviation Innovation Prize (IDL) last year. As part of its Hydrogen-to-Torque (H2T) Imponator project, the European aircraft manufacturer developed a demonstrator at the Centre for Applied Aviation Research ZAL in Hamburg that could replace the auxiliary power unit in the tail of aircraft. In future, this drive unit will combine an electric motor with a fuel cell and liquid hydrogen as fuel.

Author: Sven Geitmann

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