Can we leverage proton exchange membrane technology to power zero-emission flights?

Hydrogen fuel cell engine

Instead of using combustion to produce electricity, fuel-cells—first developed by Sir William Grove in 1838—generate electricity very effectively using an electrochemical reaction. They differ from batteries in that they need a constant supply of fuel and oxygen, often from the air, whereas a battery gets its chemical energy from materials that are already in the cell. Therefore, fuel cells can constantly generate energy as long as fuel and oxygen are available.

Airbus

Proton Exchange Membrane is the most promising technology for mobile applications (PEM). Hydrogen is utilized as the “fuel” to produce power in this kind of fuel-cell. The sole byproducts of this kind of fuel cell are heat and water.

Since this technology doesn’t produce CO2, NOx, or even very little contrails, having it on board an airplane is extremely appealing. An electric-powered aircraft is necessary to take full use of this benefit, hence there must be enough fuel cell capacity on board to produce enough power at an acceptable weight.

‘Stacking’ fuel cells to increase output

A “stack” of hundreds of these fuel cells must be electrically connected in series in order to achieve the necessary power levels for usage in an aircraft. Then, a number of similar stacks are joined to create a number of fuel cell “channels”. This modular strategy makes it possible to generate the megawatts of electricity required for an electric airplane.

Elring Klinger- a key partner with expertise in automotive fuel-cell technology

Although fuel cells are already employed in some cars, they do not meet the strict specifications needed for use in aircraft.

Regardless, Airbus has partnered with Elring Klinger-  one of the leading providers of fuel cells in the automotive industry, to manufacture and industrialize custom fuel cell stacks for the aviation industry.

These two businesses established a joint venture called “Aerostack” in 2020.

The joint work has advanced significantly in the two years since Aerostack’s founding. In Hamburg, where teams are designing, constructing, and testing fuel cell systems, the first prototype fuel cell stacks are already being reviewed by Airbus.

The design and test phase- an iterative process

It’s time to test the fuel cell systems after the teams have customized them completely.

We once experienced issues with the water management, so the drainage design is key.Even as these tests are progressing, the teams are also designing and developing the next-generation of fuel-cell stacks and systems. These will be more compact and more powerful, and which will lead to a version which can fly in Airbus’ planned ZEROe fuel-cell demonstrator. It’s an iterative process, and it doesn’t always go the way we expected, so it brings useful learning opportunities which enable us to improve the process so that it becomes even more stable and robust- Hauke Peer Lüdders, Head of Fuel-Cell propulsion systems for ZEROe Aircraft at Airbus

The test bed’s auxiliary system, which includes hydrogen, nitrogen (for the tests only), coolant, and air supplies, as well as a drainage outlet, must first be properly linked (for the derived water by-product). The test bench’s doors are shut, the electricity is turned on, and the procedure begins. The teams may then keep an eye on the reaction as it progresses, the production of byproducts, and of course the amount of electricity produced via specific screens.

SOURCE: AIRBUS

COVER: AIRBUS

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