Airbus, MTU Partner On Hydrogen Fuel Cell Propulsion

LE BOURGET—Airbus and MTU Aero Engines have outlined a three-step roadmap for development of a commercial aviation hydrogen fuel-cell engine announced here at the Paris Air Show.

The memorandum of understanding (MOU), which builds on hydrogen work conducted by both companies, calls for continued maturation of the technological building blocks through joint research projects, such as Clean Aviation, as a first step.

Airbus says the second phase will involve aligning the two partners' research and technology roadmaps on hydrogen. The outcome of these studies “would allow us to consider a third step towards the development of a fuel-cell engine for a hydrogen-powered aircraft,” adds the aircraft manufacturer.

“The aim is to combine all the work and investment we have done on the fuel-cell propulsion system and the power train—and the expertise of MTU as an engine-maker,” says Bruno Fichefeux, Airbus' head of future programs. He tells Aviation Week that “this discussion has been running for a few years and MTU has been working on fuel cell demonstrations and developing their capabilities.”

“Now we are exploring how to combine these better and how they could help us understand engine control, integration and certification—all of which is a special skill that a company takes decades to acquire,” Fichefeux adds.

Airbus has been evaluating hydrogen-powered propulsion under its ZEROe project but announced earlier this year it was suspending work on direct hydrogen combustion engines to focus on the development of hydrogen fuel cell engine technology. MTU has meanwhile been studying the technology under its Flying Fuel Cell project, a joint undertaking with German aerospace research center DLR.

The Flying Fuel Cell program, which also involves Augsburg, Germany-based liquid hydrogen system specialist MT Aerospace, aims to mature technology for zero-emissions propulsion systems suitable for regional aircraft in the 2030s. 

Beyond this, MTU is also leading the Clean Aviation technology project HEROPS (Hydrogen-Electric Zero Emission Propulsion System). Launched in early 2024, HEROPS aims to develop innovative technologies for a climate-neutral, hydrogen-powered electric powertrain based on MTU’s Flying Fuel Cell.

The MOU is “logical,” says Fichefeux, following Airbus' decision to focus on fuel cells. The alliance with MTU complements “our skill set at an engine integration level,” he adds.

In a related move, Airbus has also extended its 2020 joint venture agreement with German automotive fuel-cell supplier ElringKlinger to develop technology for zero-emission, hydrogen-fueled aircraft. “This joint venture has brought a lot of knowledge and developed one of the highest performing fuel stacks in terms of energy density,” Fichefeux says. “It’s been so promising that we recently decided to extend the JV for the next few years.”

ElringKlinger has a non-controlling interest in the joint company, while Airbus holds the majority stake.

In the JV's proton exchange membrane fuel cell, hydrogen flows into the stack and onto the anode, where it is split into hydrogen ions and electrons. Ions permeate across the membrane to the cathode, while electrons flow through an external circuit and generate power. Oxygen, in the form of air, is supplied to the cathode, where it combines with the hydrogen ions and electrons to produce water.

ElringKlinger has been focused on the use of metallic bipolar plates and specially designed membrane electrode assembly sealing to increase the high power-density of its stack. Bipolar plates distribute the hydrogen gas and air, conduct electrical current from cell to cell, remove heat from the active area, and prevent leakage of gases and coolant. They significantly contribute to the volume, weight and cost of fuel-cell stacks.