VERTONE Blog – Hydrogen: the future of green aviation?

VERTONE Blog – Hydrogen: the future of green aviation?

The pandemic will have spared no one. In the foreground of its economic victims: air transport, which has lost nearly 70% of its passengers in one year (IATA source). A bad for a good will say some, as aviation is decried for its ecological impact, as recently testified by the infiltration of the activists of Greenpeace in Roissy.

The ambition of an aviation climate neutral before 2050

In 2019, air transport was the source of 2 to 5% of greenhouse gas emissions worldwide according to the HERE IT IS and theEESI. However, the momentum for progress has been launched. According to Safran, which claims 70% of the medium-haul market share, each generation of engine reduces the carbon footprint by around 15% compared to the previous one (source Sciences et Avenir, June 2020). For its part, the IATA estimates that the work carried out on engines, fuels, aerodynamics and operations management will have made it possible in 10 years to reduce emissions per seat per km by 21.5%.

But the considerable increase in traffic, which has tripled in 20 years, requires an even more marked decrease. Europe has therefore naturally included aviation among the sectors which must contribute to achieving its ambition of climate neutrality by 2050.

In France, the € 15 billion aeronautics support plan plans to devote 1.5 over 3 years to R&D for a green and competitive industry, with the assumed objective of making France one of the most advanced countries in clean aircraft technologies. And although the development of a new aircraft is actually ten times that amount, Airbus has announced the first green, zero-emission aircraft for 2035.

Hydrogen: a promising solution, but full of challenges

You have already understood it, Gentlemen: the device that I am describing to you is quite simply a torch with oxygen and hydrogen gas. (Jules VERNES, Five weeks in a Balloon, chapter X)

In 1863, more than sixty years before Lindbergh’s pioneering feat, Jules Verne imagined in Five weeks in a Balloon a flying machine powered by hydrogen. Used since the post-war period in rockets, missiles or satellite launchers, hydrogen is a serious candidate for… propelling the green plane. It has many advantages:

  • Sharp drop in production costs.
  • Prices potentially lower than those of kerosene in 2050 (VERTIONE estimate), itself at risk of a shortage from 2030.
  • Performance, durability and capabilities that have recently achieved greatly improved, ensuring an excellent capacity of direct reciprocal transformation with electricity.
  • A mass energy density (amount of energy contained in a given mass) three times greater than oil.

However, its use is not without posing a number of technical challenges. Among these, that of the volume density of hydrogen greater than that of kerosene: for an equal tank volume, it is only possible to store a quarter of hydrogen of what would be necessary. Ariane engineers succeeded in getting around this difficulty by cooling the hydrogen to -250 ° C. But this solution requires heavy cryogenic systems, which themselves consume energy, and poses many other questions, particularly in terms of safety: the explosion of launchers on take-off is not uncommon. Otherwise, hydrogen tanks must be spherical or cylindrical, where aeronautical engineers have optimized the aerodynamics of airliners by storing fuel directly in the wings.

Finally, another “weighty” problem: that of hydrogen cells, today. too heavy to equip an aircraft.

Airbus has thus given itself five years to remove this technological barrier. : ” the […] It will then take two years to find suppliers, industrial sites, etc. Therefore, the program is scheduled for around 2028. Our ambition is to be the first manufacturer to put such a device into service in 2035. “

Hydrogen propulsion “ZEROe” planes – Airbus source

The need to deploy alternative solutions in the short term

The aircraft manufacturer seems to focus, until now, on hybrid models, thermal / hydrogen. On this model, the prototypes presented at the end of 2020 are promising since they make it possible to reduce emissions by 50 to 90%, with an additional cost for passengers of around $ 20 (source Airbus). In its wake, Airbus filed a first hydrogen aircraft patent in January 2021. However, these are propeller-driven aircraft, of the ATR (Regional Transport Aircraft) type, with a limited capacity and range of a few hundred passengers over approximately 1,000 nautical miles maximum (ie approximately 1,800 km).

The other two prototypes presented, twin-jet and flying wing, also remain below 200 passengers over 2,000 nautical miles (approx. 3,500 km). It is also the manufacturer’s ambition to position its hydrogen model of 2035 as a successor to its A320, leader, with its Boeing B757 equivalent, in the short and medium-haul market segment, and comprising 200 seats with a maximum range of 5,000 to 7,000 km.

Long haul, with their 400 seats and their range of 10,000 to 14,000 km, are still out of reach today.

Even so, the planes put into service today will fly until 2050, and those manufactured by the construction of the first commercial green plane, until 2065. The climate emergency thus pushes to think about other solutions by the advent of all hydrogen.

And while waiting for the whole hydrogen?

The most obvious is that of biofuel, which requires only marginal adaptations of the engines, on the condition, however, that green production chains and sufficiently robust to supply the market are established. According to the International Energy Agency, the cost of these fuels, today 2 to 5 times higher than that of kerosene, is however enough to explain its poor penetration rate.

In the meantime, and without the need to change the fleets: flight and air traffic management. Thales estimates that a 10% gain in fuel and emissions is possible through the implementation of a system more connected and collaborative. In concrete terms, this means a reduction in speed for passengers and therefore longer flight times.

Behind the technological challenge, the need for repositioning in the face of competition?

ATRs, the thermal range closest to the prototypes under development at Airbus, have a range of less than 2000 km, for 60 to 90 passengers, at a speed of 500 km / h … almost 10% less than the record history of the TGV.

If the standard medium-haul still point to a maximum cruising speed of 800 km / h, an increase in prices linked to the increase in fuel costs, and the decrease in this speed put them back, on a domestic scale, in head-on competition with the large train. speed. However, as the travel time gap is narrowing, it will be advantageously compensated, from the point of view of the passenger experience, by the arrival of the train in the heart of the city and the limitation of security checks.

Except now working hand in hand with airports on the implementation of strong differentiators, the advent of new rail modes, faster, and at least as clean as the TGV, could well, in the long term, ring the bell. the end of short and medium-distance air transport.

Did someone say “Hyperloop”?

An article written by Marianne Benichou

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