According to 2022 data from the European Union Aviation Safety Agency (EASA) flights originating in the European Union, together with Iceland, Liechtenstein, Switzerland and Norway – which make up the European Free Trade Association (EFTA) – account for around 12% of total greenhouse gas emissions from transport in Europe. To address this, initiatives such as the European ReFuelEU Aviation Regulation are promoting the increased use of sustainable aviation fuels. The International Air Transport Association (IATA), has also set itself the target of achieving net zero emissions by 2050.
To this end, various organisations have devised a strategy involving cutting-edge technological solutions, more efficient operations and infrastructure, and the use of new, emission-free energy sources. While Sustainable Aviation Fuel (SAF) is the most well-known option, green hydrogen also has the potential to contribute to decarbonising a complex sector such as air transport. Sustainable Aviation Fuel includes a range of sustainable fuels, some of which use green hydrogen in their production.
Furthermore, due to requirements concerning aspects such as the power required by propulsion systems or the weight of the aircraft, the electrification of air transport has been limited by the low energy storage density.
One way to integrate the direct use of green hydrogen in aviation is through hydrogen fuel cells, which generate electricity to power the propulsion engines.
Unlike conventional fuel, which is mainly stored in the wings of aircraft, hydrogen requires dedicated tanks, usually in the fuselage. One of the most efficient storage solutions is cryogenic hydrogen, i.e. hydrogen in its liquid state at very low temperatures (around -253 °C), which reduces its volume.
This stored hydrogen is used in fuel cells, where it is converted into electricity through an electrochemical reaction with oxygen. This electricity then powers the electric motors that drive the propellers, for example. This reaction produces only water vapour, which is released from the aircraft, resulting in zero CO2 emissions.
A range of projects are currently under way that will contribute to the development of an integrated hydrogen market across Europe and other parts of the world. These initiatives include large-scale electrolysis plants producing hydrogen from renewable energy sources, hydrogen transport infrastructure, and hydrogen refuelling stations at airports, among others.
These are some of the most notable projects and initiatives involving the use of green hydrogen in aviation.
The ZEROe project by Airbus is one of the most ambitious in the commercial aviation sector. The aim is to develop a hydrogen-powered aircraft that could enter service in the mid-2030s. Rather than traditional engines, the design features four electric motors powered by hydrogen fuel cells. To this end, Airbus is working on developing more powerful fuel cells.
Airbus is also leading the GOLIAT (Ground Operations of Liquid hydrogen AircrafT) project in partnership with airport operators, research institutions, and technology partners. Supported by European funding, this project aims to demonstrate the safe handling and refuelling of liquid hydrogen at airports – a crucial step towards making the everyday use of hydrogen in commercial aviation a reality.
In partnership with ElringKlinger, the company established Aerostack, which has already tested power generation systems capable of supplying up to 1.2 MW of power, a key milestone on the pasth towards commercial hydrogen-powered aircraft. All this work forms part of a wider initiative called Hydrogen Hubs at Airports, which aims to prepare airports for the use of hydrogen. Airlines from around the world are participating in this initiative, including Delta Air Lines, easyJet, and Iberia, all of which share the goal of enabling aircraft to travel long distances without leaving a carbon footprint.
ZeroAvia is one of the leading start-ups developing hydrogen-electric propulsion systems for regional aircraft. Its technology uses fuel cells that convert hydrogen into electricity to power the engines that drive the propellers. The result is a propulsion system with no direct CO₂ emissions; the only by-product is water vapour. This approach enables existing aircraft to be retrofitted by replacing their conventional propulsion system.
ZeroAvia is currently developing several modular systems, including the ZA600 for 10–20-seat aircraft and the ZA2000 for regional aircraft carrying up to 80 passengers. ZeroAvia’s strategy focuses on entering the regional and cargo flight markets first, where range requirements are lower and technology adoption can be faster. In addition to developing propulsion systems, ZeroAvia is collaborating with airlines and airports to establish hydrogen supply infrastructure, which is a key step towards the commercial adoption of this technology.
JetZero is developing a blended wing body (BWB) aircraft concept, which integrates the fuselage and wings into a single, wider and more aerodynamic structure. This design offers more internal volume than conventional aircraft, which is particularly useful for storing liquid hydrogen, as it requires large tanks.
The project is supported by research programmes linked to the National Aeronautics and Space Administration (NASA) and has attracted the interest of airlines such as United Airlines. The company plans to test a full-scale aircraft prototype around 2027, initially using conventional fuels, although the design is being developed to accomodate a future hydrogen-powered version.
The German company H2FLY focuses on developing propulsion systems based on fuel cells powered by hydrogen, which is first stored in liquid form. Its projects aim to demonstrate that this type of fuel can provide flight ranges similar to those required for commercial regional flights.
In recent years, the company has used experimental platforms to validate these systems integrating cryogenic tanks and high-power fuel cells into light aircraft. The aim is to scale up this technology for larger regional aircraft. This approach focuses on addressing one of the main challenges of hydrogen-powered aviation: storing the fuel at extremely low temperatures and distributing it within the aircraft.
The H2ELIOS project is a European initiative focused on developing hydrogen storage technologies for aviation. Led by the Spanish company Aciturri under the European Clean Aviation programme, the project aims to design structural tanks for liquid hydrogen integrated into the aircraft’s structure.
Structural integration is essential because hydrogen requires large, well insulated cryogenic tanks. By integrating these tanks into the fuselage or the aircraft’s load-bearing structure, it is possible to reduce weight and volume, thereby improving the viability of future hydrogen-powered aircraft. The project brings together European aircraft manufacturers, research centres, and technology companies to develop solutions that could be applied to future generations of commercial aircraft.
Safety is one of the most important considerations in aviation. Safety is one of the most important considerations in aviation. Therefore, before any new technology can be certified and introduced, it must meet standards that are equivalent to or higher than those currently in force, as defined by organisations such as EASA.
Hydrogen is up to 14 times lighter than air and disperses rapidly, limiting its build-up in the event of a leak reducing the likelihood of ignition in open spaces. Furthermore, in the event of combustion, its flame tends to rise vertically and dissipate more quickly than that of kerosene. These physical properties, combined with the proper management of hydrogen in the aviation sector have the potential to reduce certain risks compared with conventional fuels.
