Airbus has the ambition to develop the world’s first zero-emission commercial aircraft by 2035 (with hydrogen propulsion). Their ZEROe concept aircraft will enable to explore a variety of configurations and hydrogen technologies that will shape the development of the future zero-emission aircraft.
Airbus stated that the research into hydrogen as a potential energy carrier to power future zero-emission aircraft has been intensifying in recent years, but the road to hydrogen-powered aircraft requires significant effort inside the aviation industry and beyond. Since Airbus announced its ambition to develop the world’s first zero-emission commercial aircraft by 2035, this means that the most disruptive zero-emission technology to reduce the aviation industry’s climate impact will need to be rigorously tested, and evaluated. And hydrogen certainly stands out from the pack: according to internal calculations, Airbus estimates hydrogen has the potential to reduce aviation’s CO2 emissions by up to 50 %.
From hydrogen storage, cost and infrastructure to public perceptions about safety, the aviation sector is working to mature the technology while tackling some major challenges. Hydrogen is considered as one of the most promising zero-emission technologies for future aircrafts. However, despite the fact that hydrogen has an energy-density-per-unit mass that is three times higher than traditional jet fuel, a variety of challenges must be addressed before widespread adoption can happen. From the technical side, aeronautical engineers will need to take the technologies developed in the automotive and space industries and make the technology compatible with commercial aircraft operations, notably by bringing the weight and cost down. One specific challenge is how to store hydrogen on board the aircraft. Today, liquid hydrogen storage is among the most promising options, while storing hydrogen as compressed gas poses challenges with current aircraft weight and volume requirements. In addition, the aviation industry will need to achieve the same or better safety targets than what has been achieved with existing commercial aircraft. Indeed, extensive safety precautions are currently taken into account in the design and operation of today’s kerosene-powered aircraft. Future hydrogen-propulsion systems will, therefore need to achieve equivalent or better safety levels before hydrogen-powered aircraft can take to the skies.
Another key challenge for widespread adoption is liquid hydrogen availability and cost at airports. And for hydrogen to really achieve widespread adoption across the aviation industry, it must be made available at airports worldwide. Advancement in this area is in its infancy. One main challenge is developing the large-scale transport and infrastructure solutions required to supply airports with the necessary quantities of hydrogen needed to fuel aircraft. Hydrogen is available in vast quantities in oceans, lakes and the atmosphere, however, it must be separated from oxygen in water in order to be used for industrial purposes. Airbus is currently collaborating with both airports and airlines to ensure the necessary hydrogen infrastructure is in place. This includes research into how all airport-associated ground transport (i.e. cargo trucks, passenger buses, aircraft tugs, etc.) could be decarbonised throughout the 2020s timeframe.
Airbus is targeting the use of green hydrogen to fuel its future zero-emission aircraft. Glenn Llewellyn (VP of Zero-Emission Aircraft) believes declining costs for renewable energy and the scaling up of hydrogen production could make green hydrogen increasingly cost-competitive with existing options, such as jet fuel and sustainable aviation fuels.
Game-changing concepts for future aircraft: there are two broad types of hydrogen propulsion: hydrogen combustion and hydrogen fuel cells. Airbus’ three zero-emission “concept” aircraft – known as ZEROe – are all hybrid-hydrogen aircraft. This means they are powered by modified gas turbine engines that burn liquid hydrogen as fuel. At the same time, they also use hydrogen fuel cells to create electrical power that complements the gas turbine, resulting in a highly efficient hybrid-electric propulsion system. However, each option has a slightly different approach to integrating the liquid hydrogen storage and distribution system. Airbus engineers have conceptualised integration solutions that carefully take into account the challenges and possibilities of each type of aircraft.
The Turbofan aircraft (120-200 passengers) with a range of 2.000+ nautical miles, capable of operating transcontinentally will have two hybrid-hydrogen turbofan engines that will provide thrust. The liquid hydrogen storage and distribution system will be located behind the rear pressure bulkhead.
The Turboprop aircraft (up to 100 passengers) with a range of 1.000 nautical miles, capable of operating for short-haul trips will have two hybrid-hydrogen turboprop engines, which will drive eight-bladed propellers that provide thrust. The liquid hydrogen storage and distribution system will be located behind the rear pressure bulkhead.
With Blended-Wing Body aircraft (up to 200 passengers) the liquid storage tanks will be stored underneath the winds and the two hybrid-hydrogen turbofan engines will provide thrust.
These concepts will help explore and mature the design and layout of the world’s first climate-neutral, zero-emission commercial aircraft, which Airbus aims to put into service by 2035. As hydrogen increasingly becomes a mainstay in the development of new transport solutions like cars and buses, public perceptions on hydrogen are likely to change–which should positively influence hydrogen adoption in aircraft. The road to widespread hydrogen adoption in aviation is still long. But international coordination across industries is expected to support the development of the hydrogen economy–an important endeavour to help meet ambitious global decarbonisation targets over the next two decades.
Prepared by: Dejan Tasić, mag. inž. energ., project coordinator at Chamber of Commerce and Industry of Štajerska
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