Sustainable Aviation Fuels (SAF)

Today’s commercial aircraft have a service life of more than 25 years, during which they continue to run on liquid fuels. Even if the much-vaunted electric, hybrid and hydrogen-powered aircraft projects come to fruition as planned, the requisite rollover of present aircraft fleets will extend well beyond 2050. At current development levels, the new power technologies are also only suitable for short- and medium-haul aircraft: long-haul flights will remain reliant on kerosene power for the foreseeable future. And some 80% of all of aviation’s CO₂ emissions are generated by flights of more than 1,500 kilometers.

The key to achieving the CO₂ targets that the air transport sector has set itself is the use of Sustainable Aviation Fuels (SAF). They represent a major lever for reducing CO₂ emissions. The gradual transition from fossil kerosene to SAF has the potential to enable near CO₂-neutral aviation in the long term. At present, however, Sustainable Aviation Fuels are only available in limited volumes and are considerably more expensive than conventional kerosene. This is why SWISS is working actively, through targeted measures and collaborations, to drive the development and expand the availability of SAF together with the Lufthansa Group, its partners and its customers.

Sustainable Aviation Fuels (SAF) are produced not from fossil materials but from renewable energy sources, such as used cooking oils and fats or agricultural waste. While SAF emits similar CO₂ emissions during the combustion as conventional kerosene, its greenhouse gas emissions across the entire lifecycle are at least 80% lower. To support CO₂ savings, we calculate the required amount of SAF based on estimated flight-related CO₂ emissions and ensure that this corresponding volume is used on future Lufthansa Group flights.

There are various production pathways and different feedstocks available as energy sources (e.g.: the biomass-to-liquid process, the HEFA process, the power-to-liquid process, or the sun-to-liquid process). All of these approaches aim to reuse carbon from existing sustainable biomass or gases and convert it into fuel.

The present generation of Sustainable Aviation Fuels are largely manufactured from biogenic waste such as used cooking oil or fat. When such fuels are combusted, the process only generates as much carbon dioxide as was previously extracted from the atmosphere elsewhere – by plants, for example. So, it is only the production and the transport of these Sustainable Aviation Fuels that create additional CO₂ emissions. Compared to fossil fuels, today’s SAF generates at least 80% fewer CO₂ emissions. The feedstocks used to produce SAF do not compete with food or feed production and are subject to strict sustainability criteria defined in the EU Renewable Energy Directive (RED II) and the RefuelEU Aviation Regulation, which are verified by independent auditors.

In the future it will be possible to manufacture SAF using power-to-liquid and sun-to-liquid procedures. As the energy (electricity or heat) needed to do so will be generated from renewable sources and the carbon required will be drawn from the atmosphere, a closed carbon cycle can be created in which the fuels manufactured are almost entirely carbon-neutral.

In purely chemical terms, SAF is comparable to conventional kerosene: it is just not based on fossil raw materials. SAF is a so-called drop-in fuel which is added to fossil fuels to produce certificated Jet A-1 kerosene that is delivered to the aircraft via the existing fuel supply channels. SAF can thus be used to power existing aircraft and their engines, and can be handled using existing fueling facilities. SAF also produces fewer fine dust particles when combusted. This results in less cloud formation, which also reduces aviation’s non-CO₂ effects and its overall impact on the climate.

In view of the limited availability of biofuels, SWISS is supporting the development of solar fuels and has been a strategic partner of Synhelion, a pioneer in the sustainable solar fuel field, since early 2022. The aim of the collaboration is to accelerate the market launch of this forward-looking technology, to bring pilot production projects in Europe to fruition and to scale up global manufacturing capacities. In 2024, Synhelion opened the world's first demonstration plant for the production of solar fuel, supported by SWISS and the Lufthansa Group as partners. In 2025, SWISS became the world’s first airline to receive a symbolic delivery of sun-to-liquid fuel from Synhelion and used this quantity for the first time in regular flight operations.

Another step in advancing Sustainable Aviation Fuels is the partnership with the Swiss SAF technology company Metafuels. Metafuels has developed a process that efficiently converts green methanol into Sustainable Aviation Fuel. The technology enables the flexible use of different feedstocks, including both bio-methanol and e-methanol, and is inherently scalable. The synthetic SAF produced can be used within existing infrastructure and today’s aircraft fleets. The agreement with Metafuels strengthens both the commercial development of its technology and the long-standing commitment of SWISS to innovative Swiss solutions for more sustainable aviation.

Through these partnerships, SWISS also actively supports Switzerland as a hub for innovation and research.