A team of aerospace specialists has launched the first in-flight emissions study using 100% sustainable aviation fuel (SAF) on a wide-body commercial passenger aircraft. Airbus, German research center DLR, Rolls-Royce and SAF producer Neste have teamed up to start the pioneering ‘Emission and Climate Impact of Alternative Fuels’ (ECLIF3) project looking into the effects of 100% SAF on aircraft emissions and performance.

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. 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 in flight on a commercial aircraft too.

—Steven Le Moing, New Energy Program Manager, Airbus

Findings from the study—to be carried out on the ground and in the air using an Airbus A350-900 aircraft powered by Rolls-Royce Trent XWB engines—will support efforts currently underway at Airbus and Rolls-Royce to ensure the aviation sector is ready for the large-scale use of SAF as part of the wider initiative to decarbonise the industry.

Fuel-clearance engine tests, including a first flight to check operational compatibility of using 100% SAF with the aircraft’s systems, started at Airbus’ facilities in Toulouse, France, this week. These will be followed by the flight-emissions tests due to start in April and resuming in the Autumn, using DLR’s Falcon 20-E chase plane to carry out measurements to investigate the emissions impact of using SAF.

The Airbus A350 source aircraft and the DLR Falcon chase aircraft are operated from Toulouse, France and Oberpfaffenhofen, Germany under regulations related to the COVID-19 pandemic. The Falcon will chase the A350 above the Mediteranean Sea.

Meanwhile, further ground tests measuring particulate-matter emissions are set to indicate the environmental impact of SAF-use on airport operations.

Both the flight and the ground tests will compare emissions from the use of 100% SAF produced with HEFA (hydroprocessed esters and fatty acids) technology against those from fossil kerosene and low-sulfur fossil kerosene.

By investigating 100% SAF, we are taking our research on fuel design and aviation climate impact to a new level. In previous research campaigns, we were already able to demonstrate the soot-reduction potential of between 30 and 50% blends of alternative fuels, and we hope this new campaign will show that this potential is now even greater.

—Dr Patrick Le Clercq, ECLIF Project Manager at DLR

The SAF will be provided by Neste, a leading worldwide supplier of sustainable aviation fuel. Additional measurement and analysis for the characterisation of the particulate-matter emissions during the ground testing will be delivered by the UK’s University of Manchester and the National Research Council of Canada.