Earlier this week, Airbus announced its plans for hydrogen-powered aircraft. Teknisk Ukeblad has now interviewed VP Head of Zero Emission Aircraft Glenn Llewellyn in Airbus, to talk in more detail about the technology and the plans.
The investment is required to be able to fly renewably in the future, Llewellyn believes.
– We must include the entire ecosystem around the aircraft, and that is one of the most challenging tasks we have taken on. But there is no way out, if the aviation industry is to have a future.
Time is short: Airbus will have commercial routes in 2035. Batteries are not enough for long flights and large aircraft, Llewellyn states.
– Just take a look at the energy content of hydrogen and batteries. In hydrogen it is 33 kWh / kg, in batteries it is 0.2 to 0.3 kWh / kg. Batteries will evolve, but we have no belief that they will come close to the energy content of hydrogen.
Liquid hydrogen and advanced insulation
In trains, buses, trucks and cars that are powered by hydrogen, there is talk of compressed gas from 350 to 700 bar. It does not hold in planes. This is liquid hydrogen that has cooled down to well below 253 degrees minus.
– We will not have cooling systems on board the aircraft. The hydrogen will stay liquid with the help of advanced insulation. The hydrogen liquid will be in a tank isolated by double vacuum chambers, separated from each other. In each of the chambers there will be sensors that can sniff the smallest hydrogen leak. That means extremely high security, says Llewellyn.
Although the weight of the insulation is significantly higher than the weight of ordinary fuel tanks, the weight of the fuel is much lighter.
– Ordinary jet fuel has an energy content of 12 kWh / kg. That is, just under a third of the weight of the hydrogen liquid we need. This means that the weight of the aircraft will not be greater, perhaps less. Although the mind should be strong, they do not have to weigh that much.
Vacuum insulation is nothing new. When Norwegian Think decided to use a high-temperature salt battery instead of a lithium-ion battery, because it was more efficient and cheaper, they used vacuum to insulate. The point was to keep the salt melted and with a working temperature of around 250 degrees. After 24 hours, they had to use some electricity to keep the temperature the same, but the car could easily see in minus 40 degrees. This means that isolating an equivalent or actually smaller temperature differential with double vacuum insulation for a few hours is highly realistic.
Airbus has presented a couple of aircraft types where the hydrogen is stored in the rear of the fuselage. Llewellyn believes it will open up new design solutions, such as the wings.
– They do not have to be as thick as in today’s aircraft where they will store fuel. It gives us opportunities to reduce air resistance.
All the aircraft concepts Airbus launched this week will have hybrid engines. That is, they will have an electric motor in the core that will be able to increase the power of the motor when needed during takeoff.
– To produce electricity, we will use a fuel cell. It does not weigh much in relation to the batteries we would otherwise have needed, and we have hydrogen on board.
As Airbus has emphasized, they cannot solve all the challenges themselves if aviation is to be hydrogen-powered. They need to bring in very many other players, not least engine manufacturers that they have worked with. In a few years, they will be able to demonstrate the new engine types with them.
– We have talked to players for five to six years, as we have developed the concepts. This is something we will expand significantly, but we already have a collaboration with SAS and Easy Jet.
Not the longest routes in the first place
Llewellyn says that the three aircraft concepts they have launched will take traffic in areas such as Europe and the USA. They are not intended to take intercontinental traffic in the first place.
– This is a development we must continue to work on, but we are also looking at climate-friendly long-haul aircraft. We work with new types of fuel such as biofuel and jet fuel that are made from renewable energy converted into hydrogen.
Airbus is aware that switching to hydrogen as a fuel is a radical change for today’s aircraft. Therefore, they will have a much stricter certification program than usual, and over a long period of time.
– Of course we will not wait for fifteen years before we go up to fly. We will not wait that long before we test in the air, but then by having, for example, a hydrogen-powered engine on a traditional aircraft powered by ordinary jet fuel. This will probably happen in 2025/26. In the years ahead, we must also cooperate with aviation authorities on land. They must be involved and make it possible for the aircraft to be refueled with liquid hydrogen, as they are today refueled with jet fuel. We must work together to ensure that hydrogen is produced from renewable sources and not, like most things today, which are industrially produced from fossil sources and by-products from chemical processes.
Llewellyn believes that hydrogen aircraft will be able to compete well on commercial terms with today’s technology. Hydrogen will fall in price as the technology develops and we start more production of the gas from renewable energy sources. They believe that hydrogen will cost as little as two euros per kilogram in 2050 as the scaling effects go as they should when the industry gets started.
– We who work in Airbus are also ordinary people who feel the pressure from the climate crisis. Like everyone else, we want to be part of the solution and we believe hydrogen in aircraft will be an important part of it. This market is going to be big. I’m sure of that, says Llewellyn.