Hydrogen technology for sustainable aviation - H2FLY
Hydrogen is a great source of hope on the road to a clean and sustainable future. It is set to make steel green, cure the chemical industry of its dependence on oil and store surplus electricity from renewable sources. And it should enable a new era of flying. One of the companies working to ensure that this does not remain a dream of the future is H2FLY from Stuttgart.
"Our vision is to equip a regional aircraft with up to 40 seats with a liquid hydrogen tank for the fuel and couple it with a fuel cell," says Josef Kallo, one of the founders and managing directors of H2FLY. "This then supplies emission-free electrical energy to an electric motor, which in turn powers the aircraft - in our case a Dornier 328."
A consortium had already come together in the LuFo VI-1 programme to integrate an electric motor with a suitable propeller into the 328. The next step followed in LuFo VI-2. "Here we are partners in a project that we internally call 328 H2FC," says Josef Kallo. 328 stands for Dornier and FC is the abbreviation for Fuel Cell. In addition to H2FLY, the main partners include Deutsche Aircraft, General Electric Deutschland, Diehl Aerospace, DLR, IABG and AKG. "Our part in H2FLY is to develop a liquid hydrogen tank and fuel cell system, get it ready for testing and couple the two together," explains the electrical engineer, who also heads the Institute for Energy Conversion and Storage at the University of Ulm.
H2FLY
We want to learn where components and processes need to be improved.
Josef Kallo firmly believes that hydrogen will pave the way for clean flying. And he swears by the ultra-cold liquid form of the lightest of all elements. Unlike conventional paraffin, its conversion in a fuel cell produces only water and no climate-impacting carbon dioxide. Of course, the hydrogen could also be burnt directly in the aircraft engine, he says, adding in the same breath: "But then nitrogen oxides are produced. And the water would also be released into the atmosphere as hot vapour - which in turn has an impact on the climate."
But there is still a lot of work to be done before that happens. This is because a fuel cell in the megawatt range has not yet been built. And all the components - from the tank to the pipes to the fuel cell - still have to be brought to the point where they are suitable for aviation. How can the systems be integrated and interconnected? How will the liquid hydrogen be refuelled? How is the safety of the tank taken into account? These are all questions that H2FLY has to answer before the Dornier 328 can test the system in the air. "At the end of the 2020s, we plan to demonstrate the functionality of the propulsion system, liquid hydrogen tank, fuel cell as an energy converter, inverter for the engine and engine with propeller," says Josef Kallo, looking to the future. "In this way, we want to learn which components and which processes need to be improved and then move on to actual product development."
H2FLY
We have flown several world records with a liquid hydrogen fuel cell propulsion system.
The first version of the liquid hydrogen tanks has already been designed and tested. The second version, which will then undergo a ground test at the DLR test stand, is almost ready. The electrical engineer is confident that it will work well. "We have already gained experience with another aircraft with a smaller propulsion system," he says. "In 2023, we flew several world records with a 120-kilowatt liquid hydrogen fuel cell system in our HY4 test aircraft."
And this was not the first major success he has had with hydrogen technology in aviation. "When hardly anyone believed that it was even possible to install hydrogen technology in an aircraft, we were already researching it at DLR with LuFo support," he says. "One of our first major successes was to equip the nose wheel of an Airbus A320 with a fuel cell and a hydrogen tank." Using it to drive the 45-tonne aircraft over the airfield made a lasting impression on him. Based on his research, he and his colleagues then founded H2FLY as a DLR spin-off. And he has remained loyal to LuFo. "I consider the programme to be a very good instrument for initiating even visionary technologies to the point where they can make the leap into reality," he says. In addition to advanced technologies that are already on the verge of becoming a finished product, high-risk developments such as the fuel cell in aeroplanes also have a chance of receiving funding. "LuFo makes innovative research possible in the first place," Josef Kallo is certain. "It creates financial leeway for research projects and promotes dialogue between the various project partners enormously."
Text: Kai Dürfeld
Projektträger Luftfahrtforschung
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H2FLY GmbH
E-Mail: info@h2fly.de
www.h2fly.de