Study finds SAF cuts warming effect of aircraft contrails

SAF’s main environmental credentials are its lower CO2 emissions compared to traditional jet fuel, as it is produced from sustainable sources such as biomass rather than fossil fuels. However, the new ECLIF3 study – carried out by Airbus, Rolls-Royce, the German Aerospace Center (DLR) and SAF producer Neste – has now demonstrated that SAF can also reduce the soot particles produced when flying. This in turn hampers the formation of contrail ice crystals, reducing their climate-warming impact.

According to the study, the 100 per cent SAF blend led to a 56 per cent reduction in the volume of contrail ice crystals produced compared to Jet A-1 fuel. Climate model simulations produced by DLR found that this should correspond to at least a 26 per cent reduction in the contrails’ climate impact.

“We already knew that sustainable aviation fuels could reduce the carbon footprint of aviation,” said Mark Bentall, head of Research & Technology Programme, Airbus.  

“Thanks to 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 decarbonising air transport.”

SAF was used on both Rolls-Royce Trent XWB engines on the Airbus A350, with the measurements taken by a DLR chase plane. The ECLIF3 team has reported its findings in the Copernicus journal Atmospheric Chemistry & Physics (ACP) as part of a peer-reviewed scientific process. The study is claimed to be the first in-situ evidence of the climate impact mitigation potential of using 100 per cent SAF on a commercial aircraft.

"Using SAF at high blend ratios will form a key part of aviation's journey to net zero CO2,” said Alan Newby, Rolls-Royce, director Research & Technology.

“Not only did these tests show that our Trent XWB-84 engine can run on 100 per cent SAF, but the results also show how additional value can be unlocked from SAF through reducing non-CO2 climate effects as well.”

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