A newly released collaborative in-flight study using 100% sustainable aviation fuel (SAF) showed a reduction in soot particles and formation of contrail ice crystals compared to using conventional jet A-1 fuel. The Emission and Climate Impact of Alternative Fuels (ECLIF3) study included the participation of Airbus, Rolls-Royce, the German Aerospace Center (DLR), and SAF producer Neste.
According to the study, the number of ice crystals per mass of unblended SAF consumed was reduced by 56 compared to jet-A fuel, which could significantly reduce the climate-warming effect of condensation trails—better known as contrails.
“SAF is widely recognized as a crucial solution to mitigate the climate impact of the aviation sector, both in the short term as well as the longer term. The results from the ECLIF3 study confirm a significantly lower climate impact when using 100% SAF due to the lack of aromatics in Neste’s SAF used, and provide additional scientific data to support the use of SAF at higher concentrations than currently approved 50%,” said Alexander Kueper, v-p of renewable aviation business at Neste.
”The results from the ECLIF3 flight experiments show how the use of 100% SAF can help us to significantly reduce the climate-warming effect of contrails, in addition to lowering the carbon footprint of flying—a clear sign of the effectiveness of SAF towards climate-compatible aviation,” said Markus Fischer, DLR's divisional board member for aeronautics.
“We already knew that sustainable aviation fuels could reduce the carbon footprint of aviation. Thanks to the ECLIF studies, we now know that SAF can also reduce soot emissions and ice particulate formation that we see as contrails. This is a very encouraging result, based on science, which shows just how crucial sustainable aviation fuels are for decarbonizing air transport,” said Mark Bentall, head of the research and technology program at Airbus.
"Using SAF at high blend ratios will form a key part of aviation's journey to net-zero CO2. Not only did these tests show that our Trent XWB-84 engine can run on 100% SAF, but the results also show how additional value can be unlocked from SAF through reducing non-CO2 climate effects as well,” said Alan Newby, director of research and technology at Rolls-Royce.
This is not the first study that has shown the environmental benefits of using SAF. Research from NASA and the DLR in 2021 showed that using a 50% SAF blend can also result in up to 70% fewer ice crystal contrails at cruising altitude.