CARE-O-SENE

SAF stands for Sustainable Aviation Fuels. SAF refers to all sustainably produced aviation fuels, such as biogenic and synthetic fuels.

SAFs are divided into different generations. The first generation includes plant-based SAFs that are produced from vegetable oils. The second generation consists of SAFs produced from biomass, for example from waste and wood residues. The third and fourth generations consist of synthetic fuels. This is where the power-to-liquids (PtL) process comes into play.

For a fuel to be considered an SAF – and thus sustainable – the raw materials used are evaluated according to certain sustainability criteria. Criteria include whether there is competition with food production, how much drinking water is used and whether there is any destruction of ecosystems, for example through additional agricultural cultivation.

The key to decarbonising aviation is the technology to convert energy into liquid energy carriers (power-to-liquids; PtL) to produce SAF. One of the technologies used for this is the Fischer-Tropsch (FT) process for converting hydrogen and carbon dioxide from sustainable sources into SAF. The resulting SAFs are not based on fossil fuels like conventional kerosene but on renewably generated electricity and carbon dioxide.

The Fischer-Tropsch process converts green hydrogen and carbon dioxide into a synthetic fuel. New types of catalysts are being developed for this as part of the CARE-O-SENE project. Catalysts increase the efficiency of chemical conversion processes. This improves the process yield and significantly increases fuel production with the same amount of resources, which serves the goal of decarbonising the aviation sector.

The Fischer-Tropsch process, unlike alternative power-to-liquid processes, is already established in the market. Sasol brings over 70 years of experience on Fischer-Tropsch catalysts to the table and is the technology leader in this field.

Due to global climate protection efforts and, in some cases, mandatory blending ratios for power-to-liquid kerosene, a strongly growing demand for sustainable aviation fuels is to be expected. Since green electricity and hydrogen will be relatively scarce commodities in the foreseeable future, it is essential to use these raw materials as efficiently as possible. CARE-O-SENE has, therefore, set itself the goal of increasing the process yield to more than 80 percent, thanks to new catalysts. This means that significantly more fuel can be rendered usable with the same amount of resources.

The aircraft would then no longer run on a fossil raw material but a synthetic alternative – that is a great advantage. Nevertheless, a combustion process still takes place – with carbon dioxide as an output. However, this carbon dioxide is returned to the cycle and used as a raw material. Depending on the CO₂source, it is possible to produce partially or completely CO₂-neutral kerosene. For example, this can be captured from industrial processes or waste incineration. With CO₂-neutral SAF, no additional CO2 is released into the atmosphere.₂ , no additional CO2 enters the atmosphere.

No changes to existing aircraft or the supporting infrastructure are necessary for the use of SAF. As so-called drop-in fuels, SAF can be used for standard passenger aircraft. SAFs are already being added to conventional fossil fuels in small quantities.

By circular carbon dioxide we mean CO₂that has a biogenic origin or was directly captured from the air ("direct air capture"), then further processed in chemical processes and released again through combustion processes, as in the case of sustainable fuels.