Initial studies on use of 100% sustainable aviation fuels in commercial jets underway

A team of aerospace specialists launched the world’s first in-flight emissions study using 100% sustainable aviation fuel (SAF) on a wide-body commercial passenger aircraft. Teaming up with German research center DLR, Rolls-Royce, and SAF producer Neste, Airbus has started the pioneering Emission and Climate Impact of Alternative Fuels (Eclif3) project, looking into the effects of 100% SAF on aircraft emissions and performance.

The study will be carried out on the ground and air using an Airbus A350-900 aircraft powered by Rolls-Royce Trent XWB engines. In turn, results 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 more comprehensive initiative to decarbonize 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, in late March. These were followed by groundbreaking flight-emissions tests in April and 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 were 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 (hydro processed esters and fatty acids) technology against those from fossil kerosene and low-sulfur fossil kerosene. The SAF will be provided by Neste, a leading worldwide supplier of SAF. Additional measurement and analysis for the particulate matter emissions’ characterization during the ground testing will be delivered by the UK’s University of Manchester and Canada’s National Research Council.

“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,” said Steven Le Moing, New Energy Program Manager for Airbus. “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 certification view but identify the potential emissions reductions and environmental benefits of using such fuels in flight on a commercial aircraft, too.”

Dr. Patrick Le Clercq, Eclif Project Manager at DLR, said: “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. We hope this new campaign will show that this potential is now even greater.

“DLR has already conducted extensive research on analytics and modeling as well as performing ground and flight tests using alternative fuels with the Airbus A320 Atra research aircraft in 2015 and 2018 together with Nasa.”

Simon Burr, Director Product Development and Technology of Rolls-Royce Civil Aerospace, added: “In our post-Covid-19 world, people will want to connect again but do so sustainably. For long-distance travel, we know this will involve the use of gas turbines for decades to come. SAF is essential to the decarbonization of that travel, and we actively support the ramp-up of its availability to the aviation industry. This research is essential to support our commitment to understanding and enabling the use of 100% SAF as a low-emissions solution.”

Jonathan Wood, Neste Vice President for Europe, Renewable Aviation, added: “We’re delighted to contribute to this project to measure the extensive benefits of SAF compared with fossil jet fuel and provide the data to support the use of SAF at higher concentrations than 50%. Independently verified analysis has shown 100% Neste MY SAF delivering up to 80% reduction in greenhouse gas emissions compared to fossil jet fuel use when all life-cycle emissions are taken into account; this study will clarify the additional benefits from the use of SAF.”

Meanwhile, Airbus has also launched its Advanced Superconducting and Cryogenic Experimental Powertrain Demonstrator (Ascend) to explore the impact of superconducting materials and cryogenic temperatures on the performance of an aircraft’s electrical propulsion systems.

The introduction of superconducting materials can lower electrical resistance, meaning that electrical current can supply power without energy loss. When coupled with liquid hydrogen at cryogenic temperatures (-253 degrees C), electrical systems can be cooled to increase the overall electric propulsion system’s performance significantly.

Airbus will use Ascend to explore these promising technologies’ feasibility to optimize propulsion architecture ready for low-emission and zero-emission flight. Results are expected to show the potential for component weight and electrical losses to be at least halved as the volume and complexity of systems installation are reduced—a reduction in voltage to below 500V compared to current systems. Ascend will assess electric architectures from several hundred kilowatts to multi-megawatt applications with and without liquid hydrogen on board.

Airbus will design and build the demonstrator over the next three years at its E-Aircraft System House. Solutions that could be adapted to turboprop, turbofan, and hybrid propeller engines will be tested and evaluated by the end of 2023. This will support Airbus’ decision-making process for the type of propulsion system architecture required for future aircraft. Ascend is also expected to support performance improvements on existing and future propulsion systems across the entire Airbus portfolio, including helicopters, eVTOLs, and regional and single-aisle aircraft.

The demonstrator is hosted within Airbus UpNext, an Airbus subsidiary created to give future technologies fast-tracked development by building demonstrators at speed and scale, evaluating, maturing, and validating new products and services that encompass radical technological breakthroughs. (Story and photos courtesy of Airbus)

Watch this short video of an Airbus A350 taking flight using 100% SAF, or ordinary cooking oil: