Aviation is seen as a driver of climate change. Green flying is not yet possible. Experts believe that it could stay that way for the time being. What is the status of climate-friendly drives?
While e-mobility is slowly advancing on the ground and electric cars are more popular in Europe than ever before , passengers in the air will probably have to wait sometime for green travel. Airplanes still fly on classic kerosene and emit pollutants that are harmful to the environment. It is estimated that worldwide flight operations use around 300 million tons of gasoline each year.With consequences: According to the German Aerospace Center (DLR), global aviation accounts for 3.5 percent of global warming. Many airlines want to cut their emissions in half by 2030 and become climate neutral by 2050. But so far there are hardly any concrete alternatives to fossil fuel. Because the heavy jets in particular have an extremely high energy requirement. Finding a replacement is not easy.
“The future of aviation will be very diverse”
A comparison with electric cars is hardly possible. “An engine of a reasonably large transport aircraft with more than 100 passengers requires ten megawatts of propulsion power. In the automotive sector, a few hundred kilowatts are involved,” explains Rolf Henke, advisor to DLR and President of the German Aerospace Society (DGLR) in Conversation with tagesschau.de . The technical challenges are huge.”The future of aviation will be very diverse,” said the professor at the Aerospace Systems Department at RWTH Aachen University. Today almost all drives are based on gas turbines. That will change. Batteries are a possible solution for small aircraft, fuel cells could help with somewhat larger aircraft, and new solutions such as synthetic fuels would have to be found for long-haul flights.
All of this requires investments worth billions – in the middle of the Corona crisis, which temporarily brought air traffic to a standstill. The aviation business had almost completely collapsed. Many airlines made losses running into billions and could only be saved from bankruptcy with government aid. The aircraft manufacturers also lost a large part of their orders, and the orders were lost. A full recovery in travel demand is not expected until 2023 , despite the current strong booking figures, and the earlier dimension in the production of new machines not even until after 2024.
Climate-friendly drives only in the 2030s?
The transformation of the industry towards sustainability is therefore likely to take some time. According to a recent study by the consulting firm Roland Berger, the replacement of internal combustion engines in aircraft will pick up speed in the late 2030s. Only then can hybrid-electric drives or fuel cells for hydrogen be expected.The companies themselves also hold back expectations that are too high. Airbus announced a few weeks ago that conventionally powered aircraft would play the dominant role in most airlines’ fleets until at least 2050. However, the group is working on a hydrogen aircraft that will be launched in 2035.
Hydrogen as a beacon of hope
The green hydrogen in combination with the fuel cell is regarded as a beacon of hope, but it also brings with it pitfalls. Long-haul aircraft need a lot of hydrogen so that it cannot be transported as gas but in liquid tanks. However, this must be cooled to minus 250 degrees. The location of the tanks is also an open question. In addition, there is a completely new infrastructure for refueling.”If we have a hydrogen-powered aircraft, then we have to be able to refuel it somewhere,” said André Walter, Managing Director of Airbus in Hamburg, the NDR recently . Airbus is getting start-up assistance for this. The city of Hamburg plans to produce green hydrogen in the former Moorburg power plant from 2025 .Expert Henke estimates that thanks to the federal government’s hydrogen strategy, aircraft with direct hydrogen combustion could come onto the market in 2040. But: “We don’t even know whether hydrogen is the best of all solutions – because of the non-CO2 effects.” The water vapor that is produced when hydrogen is burned is the most powerful greenhouse gas and has a different effect at an altitude of eleven kilometers than on the ground.
Batteries still too heavy
The experts at Roland Berger see an even longer development period for battery-electric drives – until the late 2040s. “With the accumulators and batteries that we have available today, you would need around 200 tons of accumulator weight to move an Airbus A320,” Henke told tagesschau.de.However, the next generation of batteries is already imminent. This means that the battery-electric drive for small aircraft can move forward very quickly. That would be feasible by the end of the decade. Possible approval regulations are also helpful for the development of jets with fuel cells.
Will air travel remain affordable?
In order to make their aircraft more efficient in the short term, the major manufacturers are working on new designs. While Airbus is primarily focusing on wing tips, which make it possible to reduce fuel consumption, Boeing is working with NASA on a special fuselage. Thanks to new aircraft technology, kerosene consumption per passenger is currently falling by an average of two percent per year.” The improvement of the aircraft is essential,” says Henke. Because the new fuels are four to ten times as expensive as today’s kerosene. Classic technologies such as aerodynamics, lightweight construction or flight control would therefore be of great importance in order to keep ticket prices affordable.
Synthetic fuels are not enough either
For the time being, in addition to more efficient engines, only alternative fuels promise a reduction in CO2 for air traffic, for example, kerosene made from leftover food or synthetic fuels produced with a lot of green electricity (SAF). In its “Fit for 55” climate package, the EU Commission has proposed the addition of these fuels, in addition to a kerosene tax and stricter emissions trading, as a means of reducing emissions of climate-damaging CO2. According to Henke, synthetic fuels have two huge advantages: Both the airport infrastructure for the refuelling process and the aircraft do not have to be changed. “We just need to burn a different form of fuel.” Therefore, these are often referred to as a bridge to climate neutrality. However, according to the study by Roland Berger, this sustainably produced aviation fuel will only be available in slowly increasing quantities in 2025. So far, the global capacity is only sufficient for less than 0.1 percent of consumption. In May, the federal government and several associations announced that they would produce at least 200,000 tons of synthetic fuels annually for German aviation by 2030 – a third of the current demand in Germany. “It should be possible to produce a sufficient quantity of synthetic fuels by the end of this decade,” predicts Henke.
Climate-optimized flight routes as a quick solution
“A big step is still required if aviation is to become climate-friendly in one fell swoop,” emphasizes the DLR consultant. He also refers to climate-optimized routing: the jets should fly where they do the least harm to the atmosphere because the atmosphere is differently sensitive to emissions. With the right models, this is a logical and quick solution and has a huge effect.”When everything – engines, the efficiency of the aircraft and their climate-optimized operation – work together and mesh, it becomes something. But that takes time.” Perhaps by 2040. But then the flying fleet must first be replaced, i.e. the new aircraft must completely penetrate the market. “That should start with the smaller aircraft from 2030,” estimates Henke. In the case of the large long-haul aircraft, however, due to the production rates, this could take until 2050 – and thus as long as the EU has agreed to the entire Green Deal.