Airbus will start ground and flight testing this fuel cell engine architecture onboard its ZEROe demonstrator aircraft towards the middle of the decade. The A380 MSN1 flight test aircraft for new hydrogen technologies is currently being modified to carry liquid hydrogen tanks and their associated distribution systems.
“Fuel cells are a potential solution to help us achieve our zero-emission ambition and we are focused on developing and testing this technology to understand if it is feasible and viable for a 2035 entry-into-service of a zero-emission aircraft,” said Glenn Llewellyn, VP, Zero-Emission Aircraft, Airbus. “At scale, and if the technology targets were achieved, fuel cell engines may be able to power a one hundred passenger aircraft with a range of approximately 1,000 nautical miles. By continuing to invest in this technology, we are giving ourselves additional options that will inform our decisions on the architecture of our future ZEROe aircraft, the development of which we intend to launch in the 2027-2028 timeframe.”
Airbus identified hydrogen as one of the most promising alternatives to power a zero-emission aircraft, because it emits no carbon dioxide when generated from renewable energy, with water being its most significant by-products.
There are two ways hydrogen can be used as a power source for aircraft propulsion. First, via hydrogen combustion in a gas turbine, second by using fuel cells to convert hydrogen into electricity in order to power a propeller engine. A hydrogen gas turbine can also be coupled with fuel cells instead of batteries in a hybrid-electric architecture.
Hydrogen fuel cells, especially when stacked together, increase their power output allowing scalability. In addition, an engine powered by hydrogen fuel cells produces zero NOx emissions or contrails thereby offering additional decarbonisation benefits.
Airbus has been exploring the possibilities of fuel cell propulsion systems for aviation for some time. In October 2020, Airbus created Aerostack, a joint venture with ElringKlinger, a company with over 20 years of experience as both a fuel cell systems and component supplier. In December 2020, Airbus presented its pod-concept which included six removable fuel cell propeller propulsion systems.
Long touted as a sustainable fuel, hydrogen is now gaining serious traction as a possibility for aviation, and already tests are underway to prove its effectiveness.
Commercial airline jets using hydrogen would emit only water, and initial tests suggest they can be just as fast as traditional planes, carrying more than a hundred passengers per flight over thousands of kilometres. A recent report on the potential of hydrogen-powered aviation said such planes could enter the market as soon as 2035.
In today’s aircraft, wings are where the fuel is stored, and they are in no way large enough to store the hydrogen that would be needed for a long flight. Hydrogen planes of the future could have extra-large fuselages, but more likely they will be what’s called blended wing, in which the planes are shaped like large triangles. This would not only allow them to store more fuel, but also reduce fuel consumption to make the aircraft aerodynamics even better.
Planes using hydrogen would emit only water, and initial tests suggest they can be just as fast as traditional planes, carrying more than a hundred passengers per flight over thousands of kilometres.
Most of the world’s hydrogen today is produced by reforming methane from natural gas – a fossil fuel – which produces carbon dioxide. Efforts are underway to develop green hydrogen by using an electric current from a renewable source to convert water into oxygen and hydrogen and reduce emissions in its production. If that is possible, along with no emissions from the planes themselves, aviation could become a green form of travel.
There are significant challenges that remain.
If Europe were to fully achieve the environmental benefits of hydrogen-power – for example, for air travel, the production of clean – or green – hydrogen needs to be dramatically scaled up. 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 hydrogen used in Europe is categorically “clean.”
Hydrogen is a high-potential technology with a specific energy-per-unit mass that is three times higher than traditional jet fuel. Airbus notes that, if generated from renewable energy through electrolysis, given the fact it emits no CO2 emissions, it will enable renewable energy to potentially power large aircraft over long distances but without the undesirable by-product of CO2 emissions.
The reality is this: For now, we are still years away from commercial hydrogen aircraft becoming a reality, though. The refuelling infrastructure doesn’t exist yet and hydrogen is more expensive and difficult to store onboard than kerosene-based fuel. But the journey to a greener, cleaner era of flying is well underway.
- The author is an aviation analyst. Twitter handle: @AlexInAir
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