Could hydrogen planes be the future of aviation

Although 'green' planes are still in their infancy, progress across Europe is being now made

Nowadays, aviation accounts for 3.6% of EU greenhouse gas emissions. Modern planes use kerosene as fuel, releasing harmful carbon dioxide into the atmosphere. But what if there was another way?

One possible solution is to use a new type of fuel in planes that does not produce harmful emissions – hydrogen. Long-touted as a sustainable fuel, hydrogen is now gaining serious traction as a possibility for aviation, and already tests are underway to prove its effectiveness.
Planes using hydrogen would emit only water, and initial tests suggest they can be just as fast as traditional planes, carrying more than a hundred passengers per flight over thousands of kilometers.

A recent report on the potential of hydrogen-powered aviation, released last month said hydrogen could feasibly be used by 2035 to power a commercial passenger aircraft on a flight of up to 3,000 kilometres. By 2040 or beyond, a medium-range flight of up to 7,000 kilometres should also be possible, leaving just long-range flights for traditional aviation.

"That means on European soil, you could connect all the big cities in Europe using hydrogen-powered planes. By 2050, the ambitious scenario is that 40 % of the (European aviation) fleet would be powered by hydrogen," said Dr Bart Biebuyck, executive director of the Fuel Cells and Hydrogen Joint Undertaking, a European public-private partnership to accelerate the market introduction of these technologies.

But there are still significant challenges to make this happen. First and foremost, hydrogen storage technologies need to advance to carry enough liquid hydrogen in planes for these journeys. New ways of transporting hydrogen to airports will need to be devised so that planes can be refuelled on runways. And redesigns of plane interiors will be required to work out how to integrate all the necessary systems and tubing to run commercial planes on hydrogen.

‘With integration, nothing has been done yet on a big plane,’ said Dr. Biebuyck. ‘That will be a big challenge. And we still need to prepare a lot of standards, codes, and regulations. For example, what would be the requirement for hydrogen tanks testing for aviation? Still a lot of this research has not been done.’

However, some progress has been made in developing the underlying technology of hydrogen planes. In 2008, Boeing flew the world’s first hydrogen-powered plane from an airfield near Madrid, Spain, a single-seater vehicle that proved the technology was possible. And in 2016 the first four-seater hydrogen plane, built in Germany by the German aeronautical research agency (DLR), the University of Ulm and a company called H2FLY, lifted off from Stuttgart Airport.

And in Spain, a project called HEAVEN is working on integrating the four major components of such aircraft (a storage system to safely store liquid hydrogen, fuel cells to convert hydrogen to electricity, a device to control the power of the cells, and then a motor to turn a propeller) into an experimental plane. It is developing a powertrain to turn the propellers at high speed using electric power, along with similar liquid hydrogen storage systems to those that have been used in cars.

"This will be the first liquid hydrogen storage system (for planes), which will be connected with a fuel cell and an electric motor, and then flown in a flight test," Dr Josef Kallo from the DLR and a member of the HEAVEN team told Horizon Magazine. "The hydrogen storage (made by French firm Air Liquide) is built and will be finished this year. Next year will be integration time. And then the end of 2022 we will go into flight."

The powertrain being developed by the project turns the hydrogen into torque to turn the propeller. It is highly efficient and also quiet to run, producing about the same amount of noise as an internal combustion engine in a car – meaning passengers should have a pleasant, quiet flight.

For a 45-seater aircraft, a hydrogen-powered propeller plane will be capable of speeds of up to 600 kilometres per hour, compared to 850 kilometres per hour for a Boeing 747, according to Dr Kallo. While the focus at the moment is on propellers, there is also work underway to develop hydrogen-powered turbines, which are more efficient at higher speeds. ‘(A parallel) step would be to use turbine-type propulsion, using high-speed motors, which are relatively low noise,’ Dr Kallo added.

All of this means that it could very well be that in the coming decades, when your flight from Paris to Madrid or Munich to Rome could be on a green, clean flying machine, one that produces no emissions and has no impact on climate change - an exciting glimpse at our decarbonised future.

‘This is really a chance to switch from hydrocarbon-based aviation to hydrogen aviation,’ said Dr Kallo. 

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