The mission is as follows: A battery-powered wide-bodied aircraft is to fly from Paris to Singapore, one of the long-haul routes that are common today. What would be needed would be: an aircraft weighing 5,679 tons, the batteries alone would weigh 5272 tons, the electric motors 17 tons, a bit of payload would be left for passengers and cargo. The take-off weight would be more than ten times that of a fully loaded Airbus A380 or half that of the Eiffel Tower.
One could also simply say: Electrically powered long-haul aircraft, which would significantly advance the decarbonization of aviation, are ruled out as a realistic option for many decades. The figures come from a strategy paper by the European air traffic control authority Eurocontrol, which looked at various options for how aviation can actually achieve the climate neutrality it is aiming for by 2050. The study is full of bad news.
Long-haul connections of 3,000 kilometers and more account for just under nine percent of all flights that took off in the European Union in the reference year 2019. But they caused 54 percent of all emissions. For comparison: Flights of up to 500 kilometers, i.e. practically all connections in Germany and to nearby foreign countries, account for almost 30 percent of flight movements – but only six percent of emissions. The ban on domestic flights, which is often discussed in this country, would do very little in terms of emissions. And flights of 500 to 1500 kilometers, i.e. a large part of European traffic, make up 44 percent of all take-offs, but only 22 percent of the emissions.
The key to more environmentally friendly aviation in the future often lies in long-haul routes. But this is precisely the segment in which progress is so incredibly difficult to achieve. All in all, aviation is currently working on three major initiatives. For smaller machines with up to 50 seats and short distances, it seems possible to get electric or hybrid-electric drives ready for the market in the next one to two decades. Hydrogen could work for European routes and machines with up to 200 seats. Airbus is a pioneer here and wants to have developed an aircraft with well under 100 seats by 2035. Basically to prove that the concept works. The third and probably only realistic way for long-distance journeys for many decades to come are sustainable fuels that replace today’s kerosene.
But even with the so-called Sustainable Aviation Fuels (SAF), there is still an enormous amount of research work to be done. Production is far from industrial quantities: the currently available SAF covers around 0.1 percent of global demand. And as long as airlines and manufacturers are not willing to put billions into the start-up of a new industry themselves, they have to hope that other sectors will invest the money and that the synthetic fuels will not find other buyers.
One suggestion would be to break up long journeys with several stops
In the study, Eurocontrol emphasizes that given the impossibility of introducing revolutionary new technologies, SAF and the renewal of the partially outdated long-haul fleet must have priority. But many airlines are still heavily indebted after the corona pandemic and can only afford orders to a limited extent. Boeing and Airbus at least started thinking about new short- and medium-haul aircraft from the mid-1930s. But for new wide-bodied jets, there are not the slightest bit of considerations that could make flying less harmful to the environment.
Long-haul battery-powered flights are therefore not feasible for a number of reasons, the aircraft would be far too large and far too heavy. According to Eurocontrol, in order to get even remotely more realistic spheres, it would have to be possible to triple the battery density every ten years over several decades. But then other issues would still not be resolved, among other things there would still be a major safety risk because the batteries are highly flammable.
The weight would not be a problem with a hydrogen that is burned in conventional engines. But developing a huge tank in which large amounts of liquid hydrogen can be kept at minus 253 degrees Celsius for more than 13 hours is not yet possible. The hydrogen would also have to be produced in a climate-neutral manner in order to achieve the desired environmental impact. To refuel a single plane in two hours, it would take the output of solar plants that are 39 square kilometers in size – these are in Paris and Singapore.
Eurocontrol therefore proposes breaking up long-distance journeys with several stops. With fuel cells, the plane would be twice as heavy. And it gets completely absurd with solar cells: Even under the best conditions, an A380 would have to trail a trail of solar panels more than seven kilometers long in order to have enough energy. Its own surface would only provide 0.17 percent of the energy needed for launch.