Impact of alternative jet fuels on aircraft-induced aerosols

• Evolution of aerosols in aircraft plumes is simulated for alternative fuels.
• Composition of aerosols vary depending on fuel, which may modify their growth.
• Contrail formation is altered when using alternative fuels due to ice nuclei changes.
• Background particles can play an important role when alternative fuels are used.

While using alternative aviation fuels represents a promising approach to reduce the industry’s impact on climate change and local air quality, the influence of these new fuels on the chemical composition of exhaust plumes, and, in particular, on aviation-produced aerosols must be assessed. This paper studies the influence of using alternative jet fuels on induced particles, including contrails, in a near field of an aircraft.A computational model with detailed microphysics taking into account the condensation of organic species, homogeneous freezing, and soot activation was used to study the effect of different fuels on the formation and evolution of particulate matter in the exhaust plume of an aircraft flying at cruise conditions.Three different fuels were considered and compared: conventional kerosene (Jet A-1); a pure alternative fuel (with similar properties as Fischer–Tropsch (FT) or hydro-processed esters and fatty acids (HEFA) fuels); and a blend consisting of a 50/50 mixture of kerosene and the mentioned alternative fuel. Several conclusions can be drawn when using pure alternative and blended fuels instead of standard kerosene. The contribution of soluble organic matter in the composition of mixed aerosols increased on average by 29% with Jet A-1 to 45% with a blended fuel. The reduction in soot particles favors the homogeneous freezing pathway and the ice crystals formed were larger and evidenced lower number densities. The background particles can no longer be neglected, since they can account for more than 50% of the particles after 5 s behind the nozzle exit. All these changes are expected to alter the optical properties of contrails.