Rolls-Royce launches SAF research to reduce contrail formation

In the UK, Rolls-Royce is leading a new project to find smarter ways of using sustainable aviation fuel (SAF) to increase its effectiveness and role in reducing non-CO2 emissions, specifically those associated with contrail formation. Co-funded through the Non-CO2 Programme, part of the ATI Programme, the Quantifying Reduction in Thermal Contrails by Optimising SAF (QRITOS) project brings together Rolls-Royce, British Airways, Imperial College London and Heathrow.

The benefits of SAF for reducing end-to-end CO2 emissions from fuel are well understood, and SAF is expected to play a key role in aviation’s decarbonisation journey. However, in-flight measurements behind aircraft have also shown SAF’s potential to reduce the number of ice crystals in contrails and therefore the potential climate impact of these thin clouds of ice particles that can form behind aircraft.

The amount of SAF currently available is only a small proportion of aviation’s overall fuel requirements. It is typically mixed with conventional fossil fuel, resulting in wide-scale deployment at very low SAF blend ratios. However, SAF use is expected to increase in the UK with the introduction of the SAF mandate which came into force at the start of the year and will see 10% of SAF in the UK fuel in 2030 and 22% in 2040.

Constantly changing weather means different flights cause contrails at different times and locations, yet most of the potential climate impact comes from only a small proportion of flights. This creates an opportunity for smart SAF use targeting those flights expected to form persistent contrails. The QRITOS project aims to demonstrate the feasibility of this approach, at one of the world’s busiest airports. It will do this by combining data from British Airways flight trials, advanced modelling and satellite observations to monitor contrail formation following this targeted SAF usage.

The project aims to show that we can prioritise particular flights for SAF, focusing on where it can deliver the greatest environmental benefit and maximise the effectiveness of the current levels of supply.