A study looking at the impact of sustainable aviation fuel (SAF) on ground air quality has revealed that ultrafine particle emissions could be reduced by about 30%, compared with traditional kerosene.

The research, which was performed by German Aerospace Center DLR, Copenhagen Airport, Scandinavian Airlines and BP, monitored ground emissions from a Scandinavian Airlines (SAS) aircraft over a four-week period.

The SAS aircraft was operating commercial passenger flights between Copenhagen and Stockholm, powered with a blend of 65% kerosene and 35% SAF. Emissions from the aircraft were monitored three to four times daily in real-time, during the taxi between the runway and the gate, using a van that was specially equipped as a mobile laboratory.

After initially monitoring carbon dioxide and particulate matter from the exhaust clouds of several aircraft—using conventional kerosene and SAF blends—the research team focused on the SAS aircraft. They used the target aircraft’s GPS, the wind direction and the peak events to assign exhaust gases to the aircraft.

The lab’s equipment was situated 200 m from the aircraft engine, meaning it could detect and identify all particulate matter between five and 1,000 nanometers in number and size. By comparison, the diameter of a human hair is approximately 40,000 nanometers—40 times the size of the largest particulate. This was analyzed together with weather data collected from the van’s roof, including as wind direction, temperature and humidity.

By the time the emissions reached the monitoring equipment, they were only a few seconds old, so the combustion processes could be studied in real time. The researchers were able to separate the aircraft particulates, because they are much smaller than those emitted by diesel vehicles.

“It’s the first time that such extensive measurements have been conducted in an authentic airport environment, making it a highly complex experiment,” SAS said.

DLR has performed earlier studies into SAF emissions in 2015, 2018 and 2021, however these took place under comparatively controlled conditions, using dedicated flight campaigns.

“The reality of flight operations is quite different, and we want to see whether the benefits of these fuels meet expectations under these realistic conditions,” DLR project manager Tobias Schripp said.

The research forms part of the EU’s ALIGHT project, which aims to develop climate-neutral energy supplies for airports.

“The findings of this unique experiment at Copenhagen Airport showcase that using SAF not only reduces CO2 emissions but also reduces the impact of contrails, and enhances local air quality,” SAS Head of Sustainability Ann-Sofie Hörlin said.