First in-flight 100% SAF emissions study of passenger jet plane shows early promise
The aircraft entirely with Sustainable Aviation Fuel
Initial findings from a world-first study of the impact of 100% Sustainable Aviation Fuel (SAF) on both engines of a commercial jet have provided promising early results.
The "ECLIF3" study, involving Airbus, Rolls-Royce, German research centre DLR and SAF producer Neste, marks the first time 100% SAF has been measured simultaneously on both engines of a commercial passenger aircraft – an A-350 aircraft powered with Trent XWB engines by RR.
In-flight emissions tests and associated ground testing on the programme began earlier this year and have recently resumed. The interdisciplinary team, which also includes researchers from the National Research Council of Canada and The University of Manchester, plans to publish its results in academic journals towards the end of next year and 2023.
Findings from the study 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. Aircraft are currently only allowed to operate on a 50% blend of SAF and conventional jet fuel, but both companies support the drive to certify 100% SAF use.
In April, the A-350 flew three flights over the Mediterranean Sea pursued by a DLR Falcon chaser plane to compare in-flight emissions of both kerosene and Neste’s Hydro-processed Esters and Fatty Acids (HEFA) sustainable fuel. The team also carried out compliance tests using 100% SAF and no operational issues were experienced.
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 also performed. The research team found SAF releases fewer particulates than conventional kerosene at all tested engine operating conditions, which points to the potential for reduced climate impact and improvement in air quality around airports.
In addition, Sustainable Aviation Fuel has lower density but higher energy content per kilogram of fuel compared to conventional kerosene, which brings some aircraft fuel-efficiency advantages due to lower fuel burn and less fuel mass to board to achieve the same mission. Detailed analysis by the team is on-going.
The DLR Falcon chaser aircraft is equipped with multiple probes to measure emissions at cruise level down to a distance of only 100 metres from the A350 and feed them into scientific instrumentation for analysis.
In 2015, DLR performed the "ECLIF1" campaign, investigating alternative fuels with its Falcon and A-320 ATRA research aircraft. These investigations continued in 2018 with the "ECLIF2" campaign which saw the A3-20 ATRA flying with a mixture of standard jet fuel and up to 50% HEFA. This research showed the advantageous emission performance of fuel mixtures up to 50% SAF and paved the way for the 100% SAF test flights for "ECLIF3".
AVIONEWS - World Aeronautical Press Agency