Hydrogen potential: how aviation catches up with land transport in decarbonisation
Being used for land transport, hydrogen gains ground in aviation. We are still decades away from its commercial use. But it is in line with the environmental agenda of the transport sector.
Aviation is at a crossroads today. Leading engineers of the world try to decide on which kind of fuel the world will fly on in the next 15-20 years. Biofuel and hydrogen are considered the most promising alternatives to aviation kerosene. Hydrogen looks more attractive from the environmental point of view, since it does not emit carbon dioxide at all.
According to the European Green Deal, initiated by the European Commission, the EU aims to become the first climate-neutral region of the world by 2050. The possibilities of hydrogen as a new fuel have complied with these high-level political objectives.
Issues to solve
Clean Aviation Partnership and Clean Hydrogen Partnership are two proposed programmes under Horizon Europe, both define the usage of hydrogen as a future key fuel for aircraft. They focus on two key areas of activity: technologies to enable hydrogen-powered aircraft and ground-based solutions.
Due to the proposed technical roadmap, the hydrogen propulsion design and aircraft configurations must be ready in the next one-four years. The following five years must be dedicated to maturing technologies, adapting, integrating and demonstrating. So we will possibly see hydrogen-powered regional and short/medium-range aircraft by the end of the decade.
In simple terms, using liquid hydrogen allows one to either burn it in a jet engine or generate electricity using a fuel cell. The regional concept could be powered by hydrogen-hybrid turboprop engines or propeller motors powered by hydrogen fuel cells. The medium-range concept is considered to be powered by hydrogen-hybrid turbofan engines. In both cases, there is still a lot of work ahead. For example, current propulsion systems have a power of around 600 kilowatts while a scale up to 1,5-3 megawatts is needed.
The lack of regulations (norms, standards, guidelines) is another critical issue that must be solved in the nearest future. This applies not only to Europe but the whole world as the new aircraft will fly worldwide. The US return to the Paris agreements and the Chinese course towards decarbonisation gives hope to developers.
Prototypes
Manufacturers around the world have already started designing hydrogen-powered aircraft. The first hydrogen-powered passenger plane took flight in 2016. It was HY4, four-seat light aircraft designed by Pipistrel and equipped with the DLR Institute of Engineering Thermodynamics fuel cell system. There are also a lot of manufacturers experimenting with new fuels.
Among the big manufacturers, the most notable work having been done by Airbus. While Boeing concentrates on biofuel, the European aerospace corporation presented three concepts of the hydrogen-powered commercial aircraft in September 2020. Each of ZEROe concepts explores various technology pathways and aerodynamic configurations.
The first one is a turbofan design with a capacity of 120-200 passengers, capable of operating transcontinentally and powered by a modified gas-turbine engine running on hydrogen, through combustion. The liquid hydrogen will be stored and distributed via tanks located behind the rear pressure bulkhead.
The second design has a turboprop engine instead of a turbofan and is also powered by hydrogen combustion in modified gas-turbine engines. It would be capable of travelling more than 1,000 nautical miles with up to 100 passengers.
The third, “blended-wing body” design (up to 200 passengers) concept in which the wings merge with the main body of the aircraft could have a range of 2000+ nautical miles. The exceptionally wide fuselage opens up multiple options for hydrogen storage and distribution, and for cabin layout.
“This is a concept that suits the high-volume fuel inside. Compared to kerosene, hydrogen is light but bulky, it takes up much more volume. We are looking at different architecture. But I think we will definitely have the “blended-wing body” aircraft operational by 2035,” says Guillaume Faury, CEO of Airbus. Thus, the company will need a big amount of decarbonized hydrogen in the airports by 2035. According to Faury, some of them are already planning hydrogen storage in partnership with Airbus.