The ECLIF3 study of inflight emissions using SAF, with Airbus A350 jet and a DLR Falcon chaser aircraft.

Early Data from Airbus In-Flight SAF Test Called Positive

Nov. 29, 2021
Researchers say preliminary results show SAF releases fewer particulates than conventional fuel at all tested engine operating conditions, confirming the potential to reduce climate impact.

Airbus SA reported promising early results from its study of 100% sustainable aviation fuel’s (SAF) impact on both Rolls-Royce Trent XWB engines powering an Airbus A350 commercial jet. The ECLIF3 study united Airbus, Rolls-Royce, a German research center called DLR, and SAF producer Neste, and is described as the first time 100% SAF has been measured simultaneously on both engines of a commercial passenger aircraft.

In-flight tests featured a DLR Falcon chaser aircraft equipped with multiple probes to measure emissions at cruise level down to a distance of only 100 meters from the A350, which data were submitted for analysis using scientific instrumentation.

“In-flight testing of the A350 offers the advantage of characterizing direct and indirect engine emissions, including particulates from behind an aircraft at high altitude,” explained Steven Le Moing, New Energy Programme Manager at Airbus.

The interdisciplinary team also includes researchers from the National Research Council of Canada and The University of Manchester. Their results are expected late next year, as airframe and engine builders work to reduce the level of carbon emissions ascribed to commercial aviation.

SAF is produced using waste oils from biological sources (e.g., cooking oil, other non-palm waste oils from plants, agricultural residue, or non-fossil CO2), or solid waste from homes or businesses (e.g., packaging, paper, textiles, food waste.)

Currently, commercial aircraft are certified to operate on a maximum of 50% SAF blended with conventional jet fuel, though aircraft and jet-engine manufacturers have made commitments to increase the effective applicability of the alternative fuel.

Airbus reported that in-flight emission tests using 100% SAF and a HEFA/Jet A-1 fuel blend resumed this month, while ground-based emissions testing to quantify the benefits of SAF on local air quality were performed too.

Researchers found SAF releases fewer particulates than conventional kerosene at all tested engine operating conditions, confirming the potential to reduce climate impact and improve air quality near airports.

“SAF has been shown to have a significantly lower carbon footprint over its life cycle compared to conventional jet fuel and now we are seeing it is advantageous in reducing non-CO2 effects too,” stated DLR board member Markus Fischer. “Tests such as these are continuing to develop our understanding of 100% SAF, its use in flight and we are seeing positive signs for its potential in climate mitigation."

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