Airbus, Rolls-Royce, Neste and German research center DLR have teamed for the world’s first inflight study of the effects on emissions and performance of using 100% sustainable aviation fuel (SAF) on a widebody passenger aircraft.  

The “Emission and Climate Impact of Alternative Fuels” (ECLIF3) project uses an Airbus A350-900 aircraft powered by Rolls-Royce Trent XWB engines. The project will support efforts at Airbus and Rolls-Royce to ensure the aviation sector is ready for the large-scale use of SAF. 

Fuel-clearance engine tests, including a first flight to check operational compatibility of 100% SAF with the aircraft systems, have started at Airbus facilities in Toulouse, the partners said March 18.  

Flight-emissions tests are due to start in April and will resume in the autumn, using DLR’s Falcon 20-E “chase plane” to carry out measurements to investigate the emissions impact of using SAF. Meanwhile, further ground tests measuring particulate-matter emissions are set to indicate the environmental impact of SAF-use on airport operations. 

The launch comes as SAFs are in the spotlight as part of wider aviation industry efforts to reduce environmental impact. The European Commission (EC) is set to present a proposal on SAF, including a mandate for their use. The new proposal is part of the broader European Green Deal which aims to see the continent achieve a net-zero-carbon economy by 2050. The EC has previously said the SAF proposal will be presented in the first quarter of 2021. 

The partners in the ECLIF3 project said both flight and ground tests would compare emissions from the use of 100% SAF produced with HEFA (hydroprocessed esters and fatty acids) technology against those from fossil kerosene and low-sulphur fossil kerosene supplied by Neste.  

The UK’s University of Manchester and the National Research Council of Canada will provide additional measurement and analysis for the characterization of the particulate-matter emissions during the ground testing. 

“SAF is a vital part of Airbus’ ambition to decarbonize the aviation industry and we are working closely with a number of partners to ensure a sustainable future for air travel,” Airbus New Energy program manager Steven Le Moing said. “Aircraft can currently only operate using a maximum 50% blend of SAF and fossil kerosene; this exciting collaboration will not only provide insight into how gas-turbine engines function using 100% SAF with a view to certification, but identify the potential emissions reductions and environmental benefits of using such fuels inflight on a commercial aircraft too.”

Boeing’s ecoDemonstrator program in 2018 marked the first time a large commercial transport was flown using 100% paraffinic SAF—though in that case the testing was performed using the freighter version of the 777.