One possible solution is to use a new type of fuel in aircraft that does not produce harmful emissions - hydrogen. Long presented as a sustainable fuel, hydrogen is now gaining power as a possibility for aviation, and tests are already underway to prove its efficiency.
Planes using hydrogen would only emit water, and initial tests suggest they can be 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 aviation has said that such aircraft could enter the market as early as 2035.
There are still significant challenges in getting there. But if they can be overcome, the future of aviation could be much greener than it is today and be a functional component of a carbon-free world.
Hydrogen aircraft would be aesthetically similar to traditional aircraft, but with a slightly longer length. Smaller planes would likely use propellers, with hydrogen fuel cells providing electric propulsion to spin the propellers. Larger planes could burn hydrogen to power reactors.
The hydrogen aviation report, released on June 22, indicated that hydrogen could be used by 2035 to propel a commercial passenger aircraft on a flight of up to 3,000 kilometers. By 2040 or beyond, mid-range flight of up to 7,000 kilometers should also be possible, leaving only long-range flights for traditional aviation.
"By 2035, it should be possible for a short-range aircraft," said Dr. Bart Biebuyck, executive director of the Joint Fuel Pells and Hydrogen Joint Undertaking, a European public-private partnership to accelerate the introduction to the market for these technologies, which jointly commissioned the report. “This means that on European soil, you can connect all the major cities in Europe using hydrogen planes. By 2050, the ambitious scenario is that 40% of the fleet (of European aviation) would be powered by hydrogen.
Achieving these goals will depend on a number of factors. Above all, hydrogen storage technologies must advance to transport enough liquid hydrogen on planes for these trips. New ways of transporting hydrogen to airports will have to be devised so that airplanes can be refueled on the runways. And the redesign of the aircraft interiors will be necessary to determine how to integrate all the systems and tubes necessary to run commercial aircraft on hydrogen.
"With integration, nothing has been done on a grand plan yet," said Dr. Biebuyck. “It will be a great challenge. And we still have to prepare many standards, codes and regulations. For example, what would be the requirement for aviation hydrogen tank testing? Much of this research has yet to be done.
However, progress has been made in developing the technology behind hydrogen aircraft. In 2008, Boeing flew the world's first hydrogen aircraft from an airfield near Madrid, Spain, a single-seat vehicle that proved that technology was possible. And in 2016, the first four-seat hydrogen aircraft, built in Germany by the German aeronautical research agency (DLR), the University of Ulm and a company called H2FLY, took off from Stuttgart Airport.
'We cannot defeat climate change without decarbonising aviation.'
Dr Bart Biebuyck, Executive Director, FCH JU
Hydrogen aircraft have essentially four main components - a storage system to safely store liquid hydrogen, fuel cells to convert hydrogen into electricity, a device to control the power of the cells, then a motor to turn a propeller. In order to make complete commercial aircraft, these four areas must be sufficiently developed.
In Spain, a project called HEAVEN is working on the integration of these components in an experimental plan. He is developing a powertrain to spin propellers at high speed using electric power, as well as liquid hydrogen storage systems similar to those used in cars.
"This will be the first liquid hydrogen storage system (for airplanes), which will be connected to a fuel cell and an electric motor, then piloted during a flight test," said Dr. Josef Kallo of DLR and member of the HEAVEN team. “The hydrogen storage (carried out by the French company Air Liquide) is built and will be completed this year. Next year will be the time of integration. And then at the end of 2022, we will go in flight. »_113_ The powertrain developed by the project transforms hydrogen into torque to turn the propeller. It is very efficient and also quiet to operate, producing about the same amount of noise as an internal combustion engine in a car - which means that passengers should have a pleasant and quiet flight.
For a 45-seat aircraft, a hydrogen propeller aircraft will be capable of speeds of up to 600 kilometers per hour, compared to 850 kilometers per hour for a Boeing 747, according to Dr. Kallo. Although the focus is currently on propellers, work is also underway to develop more efficient hydrogen turbines at higher speeds. "A (parallel) step would be to use turbine type propulsion, using high speed motors, which are relatively quiet," added Dr. Kallo.
Most of the hydrogen in the world today is produced by the reforming of methane from natural gas - a fossil fuel - which produces carbon dioxide. However, efforts are underway to develop green hydrogen using an electric current from a renewable source to convert water to oxygen and hydrogen and reduce emissions in its production. If possible, without emissions from the planes themselves, aviation could become a truly green form of travel.
"By 2050 we must (become) a carbon neutral society and the aviation sector must contribute to it," said Dr Biebuyck. “Of course, it is not only aviation that will have to adapt. We all have to work together. But we cannot defeat climate change without decarbonizing aviation.
Europe seems ready to play a major role in this area, leading the development of many hydrogen-based technologies, including hydrogen aircraft. "Europe is far ahead," said Dr Kallo. “There are projects in the United States and in China. But they have not shown the level of progress we have. "_113_ And it could very well be that in the decades to come, your flight from Paris to Madrid or from Munich to Rome could be done on a green and clean flying machine, which produces no emissions and has no impact on change change - an exciting insight into our carbon-free future.
"This is truly a chance to move from hydrocarbon based aviation to hydrogen aviation," said Dr. Kallo.
In order for Europe to take full advantage of the environmental benefits of hydrogen, the production of clean - or green - hydrogen must be considerably increased.
Clean hydrogen is produced from water using an electric current from a renewable source, rather than from fossil fuels. Today, only a tiny fraction of the hydrogen used in Europe is clean.
On July 8, the EU released a hydrogen strategy outlining a vision for how Europe can increase the production, distribution and storage of clean hydrogen.