Besides lowering an aircraft’s carbon emissions, using a 50/50 sustainable aviation fuel (SAF) blend can also result in 50 to 70 percent fewer ice crystal contrails at cruising altitude, further reducing aviation’s impact on the environment, according to in-flight research by NASA and the German Aerospace Center (DLR). Ice crystal contrail formations can linger in the upper atmosphere for hours and affect the way Earth is heated and cooled, NASA said.
“We know that contrail formation from jet exhaust has a larger, more immediate impact on climate than carbon dioxide emissions,” said Richard Moore, a NASA scientist at Langley Research Center in Virginia. “This research shows we have an opportunity, using alternative fuels, to make immediate changes that could help the planet.”
Jet engine exhaust includes water vapor and soot particles. As the water vapor cools, it condenses and ice crystals form when this supercooled water interacts with exhaust soot or other particles naturally in the air.
By using SAF, jet engines release fewer soot particles, resulting in fewer ice crystal formations. In addition, the crystals that do form are larger, meaning they fall more quickly and melt in the warmer air below.
During the recent trials, DLR’s research A320 burned SAF while NASA’s DC-8 “flying laboratory” trailed behind, sampling and analyzing gases and particles in the A320’s wake.