The technology already exists: a range of alternatives could replace the kerosene currently used in aviation. In Switzerland, for example, kerosene must already contain at least 2% biogas. The EU will also introduce the same requirement from 2027. By 2030, the figure is set to reach 6%, and by 2050 as much as 35%.
Biogas is produced from food waste, but can also be made from cooking oil, frying oil or animal fats. “Reusing these fats for fuel production is a good thing in itself,” says Paula Castro, a Professor of Energy and the Environment. "The problem arises, however, when this market is exploited and, for example, palm oil or other edible raw materials are cultivated solely for use as fuel.” Important resources that could otherwise be used as food are thus wasted. What is more, land is being put under unnecessary strain. This practice is not permitted anywhere in the world, but monitoring and preventing abuse is just as difficult.
Synthetic fuels as an alternative
For this reason, the long-term goal is to switch to synthetic fuels. One of these is hydrogen. Put simply, hydrogen is produced by combining water with carbon dioxide. Its production therefore requires large quantities of water, on the one hand, and CO₂, on the other, for example from industrial sources. Above all, however, production requires enormous amounts of electricity. This is not only expensive, but also highly inefficient. If you compare the amount of fuel obtained from the process with the amount of electricity required to produce it, the relationship is hardly proportionate. And yet, unlike road transport, air travel cannot be easily electrified, as today’s batteries are not powerful enough for flying.
The ReFuel research consortium, which includes the ZHAW, is therefore working on new processes. The aim is to create new molecular chains from methanol and hydrogen, thereby increasing the overall yield of kerosene. However, these processes are still under development and are not yet commercially available.
Commercial-scale facilities still lacking
One of the key challenges in the production of synthetic fuels is that there is currently no commercial facility capable of producing them on a large scale. What is needed are investors who are prepared to back these new solutions. “So far, everyone is waiting,” explains Professor Castro. “The first facility is always the most expensive, and up until now no one has been willing to take that risk.”
In Switzerland, there have been discussions about building such a plant, she continues, but this would take up a great deal of space, which is already scarce in Switzerland. In addition, the facility would have to use renewable energy sources. Yet these are not available in unlimited quantities in Switzerland. Resources that could potentially be put to better use elsewhere in the country would therefore be required. According to Paula Castro, the EU faces the same challenges. For this reason, efforts are currently being made to collaborate with countries that are well suited to year-round solar energy production, such as Oman in the Middle East. The new fuel would therefore be produced there and then transported to Europe by ship.
An ecological contradiction? “Not necessarily,” says Castro. “Unlike air travel, shipping can be electrified relatively easily,” she explains. The fuel could therefore be transported to Europe with low emissions and then distributed to different countries through pipeline networks. According to Castro, a far greater challenge with this solution is the reliance on imports and the related security considerations, which carry significant weight in today’s geopolitical climate.
Political, regulatory and economic dependencies
The issue is therefore a complex one. The challenge is less about developing the most suitable technology and more about aligning the various interests and dynamics at play in the realms of politics and business. This is precisely what Paula Castro’s research group is investigating on behalf of the Swiss Federal Office of Energy. Switzerland wants to know when, where and how financial resources should be deployed in order to achieve the best possible outcome for the economy, the environment and society.
Wouldn’t it be easier to stop flying altogether? Paula Castro disagrees: “You cannot forbid people from flying. We need global solutions to reform air travel while placing as little strain on the environment as possible.” Switzerland, she says, is a rich country. “If we cannot afford it, who can?”
The initial findings from Paula Castro’s research group are expected to be published at the end of August 2026.
