Results from the world’s first in-flight study of the impact of using 100% sustainable aviation fuel (SAF) in both engines of a commercial aircraft show a reduction in soot particles and formation of contrail ice crystals compared to using conventional Jet A-1 fuel.

The ECLIF3 study (earlier post), in which Airbus, Rolls-Royce, the German Aerospace Center (DLR) and SAF producer Neste collaborated, was the first to measure the impact of 100% SAF use to emissions from both engines of an Airbus A350 powered by Rolls-Royce Trent XWB engines and followed by a DLR chase plane.

The Airbus A350 and DLR Falcon in test flight. Source: Airbus, S.Ramadier

Compared to a reference Jet A-1 fuel, the number of ice crystals per mass of unblended SAF consumed was reduced by 56%, which could significantly reduce the climate-warming effect of contrails.

Global climate model simulations, conducted by DLR, were used to estimate the change in the energy balance in Earth’s atmosphere—also known as radiative forcing—by contrails. The impact of contrails was estimated to be reduced by at least 26% with 100% SAF use compared to the Jet A-1 reference fuel used in ECLIF3.

These results show that using SAF could significantly reduce the climate impact of aviation in the short term by reducing non-CO₂ effects such as contrails, in addition to reducing greenhouse gas emissions, such as CO₂ emissions over the life cycle of SAF when compared to using fossil jet fuel.

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

—Markus Fischer, DLR Divisional Board Member for Aeronautics

The research team has reported its findings in the journal Atmospheric Chemistry & Physics. The ECLIF3 program, which also includes researchers from the National Research Council of Canada and the University of Manchester, conducted in-flight emissions tests and associated ground tests in 2021.

Resources

• Märkl, R. S., Voigt, C., Sauer, D., Dischl, R. K., Kaufmann, S., Harlaß, T., Hahn, V., Roiger, A., Weiß-Rehm, C., Burkhardt, U., Schumann, U., Marsing, A., Scheibe, M., Dörnbrack, A., Renard, C., Gauthier, M., Swann, P., Madden, P., Luff, D., Sallinen, R., Schripp, T., and Le Clercq, P.: Powering aircraft with 100 % sustainable aviation fuel reduces ice crystals in contrails, Atmos. Chem. Phys., 24, 3813–3837, doi: 10.5194/acp-24-3813-2024, 2024.