European aircraft giant Airbus believes in hydrogen to propel aviation in the future. It solemnly pledged to have an H2 airplane commercially ready by 2035. The hydrogen-powered fuel cell engine showed last week could be the ideal solution for planes for mid-haul flights with up to 100 passengers and a range of 1 000 nautical miles (1 852 km).
Airbus will start ground and flight testing this fuel cell engine architecture onboard its ZEROe demonstrator airplane towards the middle of the decade and in future ZEROe aircraft in the 2027-2028 timeframe. The A380 MSN1 flight test aircraft for new hydrogen technologies is currently being modified to carry liquid hydrogen tanks and their associated distribution systems.
Electromechanical versus combustion
Fuel cells generate electricity through an electrochemical reaction rather than via combustion. Burning hydrogen in a combustion engine for planes is also an option, as Rolls Royce and EasyJet showed a modern turboprop airplane engine running on green hydrogen. It didn’t fly yet, but it was successfully ‘ground tested’ using a converted Rolls-Royce AE 2100-A regional aircraft turboprop engine.
The next phase will convert jet engines to run on hydrogen, aimed mainly at long-haul flights. Airbus presented in September 2020 three concepts of zero-emission airplanes using liquified ‘green’ hydrogen as fuel. It believes these planes will be ready to start test-flying by 2028 and ready to fly by 2035 commercially. The fuel cell engine presented last week could propel smaller airplanes as soon as 2030
Fuel cell stacks and channels
For an electric airplane, you’ll need sufficient fuel cell capacity on board to generate enough power at an acceptable weight level. “One single fuel cell is only a few millimeters thick and roughly the size of a letter envelope. It does not release much energy,” Airbus explains.
“Therefore, to realize sufficient power levels for use in an aircraft, hundreds of these fuel cells need to be electrically connected in series to form a ‘stack’. Subsequently, several such stacks are combined into multiple fuel cell ‘channels’. With this modular approach, the megawatt power levels– needed for an electric aircraft – are achievable.”
To accomplish this, Airbus turned to automotive partners with great experience in fuel cells, like German ElringKlinger, and set up a joint venture in 2020 called Aerostack. ElringKlinger is developing fuel cells with the EKPO joint venture with French Tier 1 automotive supplier, Plastic Omnium.
The German family-owned group employing some 10 000 people is a supplier to almost all car manufacturers. It has been active in the subfield of battery and fuel cell components for some years already. The EKPO entity is housed at ElringKlinger’s Dettingen factory near Stuttgart. The latter is bringing in its fuel cell production with a capacity of 10 000 units per year.
Through Aerostack, Airbus and ElringKlinger got partial funding for their project from the German H2Sky Project, set up to develop optimized 100-200 kW fuel cell stacks for use in the primary propulsion system of an airplane. The latter receives €26.5 million in funding from the National Innovation Programme for Hydrogen and Fuel Cell Technology. Around €18 million is self-financed from the consortium with other partners.
The collaborative work is well underway two years after Aerostack was formed, says Airbus. Airbus is already evaluating the prototype fuel cell stacks in Hamburg, where the teams are designing fuel cell systems and assembling and testing them.