Paris (AFP)

The development for 2035 of a "carbon neutral plane" operating on hydrogen, announced Tuesday by the French government, is an "ambitious" but "feasible" objective agree the industrialists, even if many technological barriers remain to lift to arrive at "zero emissions".

While the pressure on the ecological cost of air transport - which represents between 2 and 3% of carbon dioxide (CO2) emissions according to the International Civil Aviation Organization - continues to mount in public opinion, this objective is advanced by 10 years compared to the initial projects of the sector.

The development of this "green plane" should cost tens of billions. By 2022, it will receive 1.5 billion euros in public funding.

"It's ambitious but doable," says Eric Trappier, president of the French Aeronautical and Space Industries Group (Gifas). "We are absolutely convinced that it is feasible," says the boss of the giant Airbus Guillaume Faury. "It’s a very credible battle plan, that doesn’t mean there are not many challenges and a lot of work to do by then," he told AFP.

Each new generation of aircraft reduces the carbon footprint by around 15%, noted a few months ago Philippe Petitcolin, general manager of the engine manufacturer and equipment supplier Safran, whose engines equip 70% of medium-haul aircraft worldwide .

To meet the objective of the global aviation sector to reduce its CO2 emissions by half in 2050 compared to their level in 2005, it was already necessary to jump a generation and reduce this carbon footprint by 30%, according to him. The march is therefore even higher towards the "zero emission" aircraft, especially when the sector sees its activity melt under the effect of the coronavirus crisis.

"It is not won, it is a very ambitious goal but we will work to make it realistic. There are a lot of points to settle to obtain this result of 2035 with a hydrogen plane", said Wednesday M. Petitcolin on BFMBusiness.

For a low-carbon aircraft in 2035, "it gives us five years to develop the technologies", some of which are emerging, before starting the preparation of the program that will have to be launched "in 2027 or 2028", explains Guillaume Faury. According to him, the regional commercial planes, smaller, are "probably a good support to enter the low-carbon aviation".

- The question of storage -

At the center of the questions: what fuel for which engine? The solution put forward by the French government is hydrogen propulsion, the electric requiring too much battery weight.

But the question arises of storage, hydrogen being much larger than kerosene. "We would need storage space four times greater than what it is on the plane for an identical mission," said AFP Jérôme Bouchard, aeronautical expert at the firm Oliver Wyman. And its cryogenization at -253 degrees to reduce its volume, as in the Ariane rocket, would not be without raising the question of security.

It will also be necessary to "review the aerodynamic shapes" of this future aircraft, because "the current concept of fuselage and wings will not be enough", according to him.

Hydrogen could be used either directly as fuel in slightly modified engines, or to power a fuel cell which would produce electricity directly feeding an electric motor, explains the expert.

And to produce hydrogen, "you need electricity and green sources of electricity so as not to place the burden of CO2 emissions on other elements of the chain", he argues.

Green aviation also requires better management of traffic and flight paths in an often congested sky, argues Patrice Caine, the boss of Thales, a technology group that positions itself as the world leader in management systems flight and air traffic management.

With a more "connected and collaborative" system, "the savings in fuel and CO2 emissions are far from negligible, we are talking about 10%," he explains to AFP. And there is "no need to wait until 2035, we are talking about savings from 2023".

© 2020 AFP