

The challenge of decarbonising commercial aviation
Faced with increasing pressure to reduce CO₂ emissions, the commercial aviation sector is exploring the feasibility of using more sustainable fuels. Although some challenges still exist, SAF (Sustainable Aviation Fuel) and green hydrogen are presented as credible solutions to decarbonise air transport.
While the aviation sector has reduced its carbon footprint by 50% over the last 30 years, it still accounts for 2.5% of global CO₂ emissions, 13.9% of freight emissions, and relies predominantly on conventional aviation fuels.
Within the European framework of becoming the first climate-neutral continent by 2050, achieving this milestone will necessarily require an industrial sector that advances the development of cutting-edge technologies for cleaner fuels, driving hybrid aviation engine propulsion and efficient air traffic management.
Unlike what we have seen in the automotive industry, the aviation sector cannot be so easily electrified. Battery-electric propulsion is only feasible for small aircraft or regional aircraft making short journeys and carrying smaller loads, at least for the foreseeable future.
In this regard, Abel Jiménez, chief engineer at engine manufacturer ITP Aero, notes that ‘for at least the next two decades, the main mode of aircraft propulsion will continue to be the combustion engine’. Therefore, the transition to carbon-neutral aviation will require the adoption of more viable and immediate alternatives based on current technological capabilities.
Sustainable Aviation Fuel (SAF)
SAF (Sustainable Aviation Fuel) can be used in conventional aircraft engines without requiring major technical modifications. It is a fuel produced from organic waste, such as used cooking oil, agricultural waste or residues from the agri-food industry. Proponents argue that it can reduce CO₂ emissions by up to 80% compared to traditional kerosene.
However, producing and distributing SAF is not a simple task. On the one hand, the supply of the necessary feedstock is increasingly scarce, on the other, collecting oil from thousands of kitchens and transporting the fuel from refineries to thousands of airports is expensive, labour-intensive, and time-consuming.
Moreover, in order to maintain the sustainability of this fuel, SAF manufacturers cannot compete with normal food production through the use of prime agricultural land, the use of water or non-waste feedstocks.
This makes the final product currently two to two and a half times more expensive than conventional aviation fuel. Scaling up this process to lower costs involves the creation of new supply chains, and doing so sustainably is not easy either.
Thus, we are far from having the capacity to sustainably produce and distribute SAF in large quantities. Currently, this fuel represents only a tiny fraction of the total needs of the aviation sector and, although, according to the International Air Transport Association, its production will triple this year compared to 2023 levels, it will only cover 0.53% of aviation fuel demand.
Hydrogen, a promising technology
Many aviation industry analysts believe that the use of green hydrogen or hydrogen produced from renewable energy is the way forward. The main advantage of hydrogen is that it does not emit CO₂ during combustion; the end product is water. This makes it an ideal technology for achieving climate neutrality.
It can be used as fuel in combustion engines or in fuel cells that generate electricity to power electric motors. Companies such as Airbus, Rolls-Royce, Safran and MTU have announced plans to develop hydrogen-powered commercial aircraft that could be in operation by 2035.
David Álvaro Granero, Engineering Senior Site Rep (ESSR) at Airbus, indicated that they are working to offer 100% SAF capacity on their aircraft by 2030 and, as for hydrogen, they are evaluating three options: direct combustion of liquid hydrogen with a turboprop or turbofan, hydrogen fuel cells for electric propulsion and a hybrid architecture combining the two options.
Hydrogen produced from renewables is not as affordable as kerosene, but it is not as expensive as SAF and would be much easier to scale up its production. However, as an aviation fuel, it also has some disadvantages, such as its low bulk density and the difficulty of storing and transporting it because of its flammability and risk of explosion. This will require airports to invest heavily in building a whole new infrastructure for its storage and distribution.
Ultimately, it is clear that to be effective, the set of solutions adopted to decarbonise the aviation industry will require the collaboration of all aviation stakeholders globally.
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