The world’s first transatlantic flight run on 100% sustainable aviation fuel is taking off today from London Heathrow, bound for New York.

The Virgin Atlantic Boeing 787 flight, which is taking off on 28 November 2023 from London Heathrow (LHR) to New York John F Kennedy Airport (JFK), is the first to showcase the feasibility of flying on 100% sustainable aviation fuel (SAF) over such a distance.  

Partly funded by the Department for Transport, the Virgin Atlantic-led project called Flight100 involves a consortium comprised of Imperial College London, University of Sheffield, Boeing, Rolls-Royce, BP, and others, to demonstrate SAF as an alternative to regular jet fuel. 

The project is a significant milestone in decarbonising the aviation industry, which accounts for around 3% of human influence on climate change as a result of CO2 and non-CO2 emissions. Using SAF could reduce carbon dioxide (CO2) emissions by up to 70% compared to fossil-based jet fuel over its lifecycle. 

"Historical data tells us that a significant proportion of LHR-JFK flights form contrails that we can see in satellite imagery. SAF-formed contrails are likely to be shorter-lived, so this provides us an unparalleled opportunity to track and analyse these contrails and study their likely climate effect.”  Dr Roger Teoh Department of Civil and Environmental Engineering

As well as CO2, flying also releases particulate matter (PM), which can cause contrails – white fluffy streaks in the sky – to form. Evidence is growing that contrails, especially those that persist at night, contribute significantly to the climate impact of flying by trapping heat and causing a greenhouse effect in the atmosphere – and that we can minimise their warming effects by using sustainable aviation fuel, altering flight altitude and flying during daytime. 

Imperial and Sheffield researchers are leading the scientific work to assess the climate effects of the Flight100. In the lead-up to take-off, the team, which includes Imperial PhD researchers Georgia Gamble and Joel Ponsonby, measured particulate matter emitted by a smaller scale aircraft engine, and confirmed that SAF reduced particulate matter emissions. The team also used historical air traffic and weather data to analyse the contrails formed on the LHR to JFK route and over the North Atlantic region generally. 

After the flight, they will analyse these effects using on-board flight data, weather data and satellite imagery to estimate the amount of particulate matter released and track any contrails formed by the flight. They hope to be able to compare the contrails produced by this specific flight to those of other flights that use fossil jet fuel in the same region at the same time. 

Dr Marc Stettler, from Imperial's Department of Civil and Environmental Engineering, who leads the Imperial team and is a passenger on the flight, said: “If the atmosphere is sufficiently cold and humid, water will form droplets on particulate matter emitted by the engine. These droplets quickly freeze and then collectively become a contrail. If there are fewer particles, as we expect from the use of SAF, the contrail won’t last for as long and will therefore have a smaller climate effect.” 

Dr Roger Teoh from Imperial’s Department of Civil and Environmental Engineering, who is part of the project team, said: “Historical data tells us that a significant proportion of LHR-JFK flights form contrails that we can see in satellite imagery. SAF-formed contrails are likely to be shorter-lived, so this provides us an unparalleled opportunity to track and analyse these contrails and study their likely climate effect.” 

As well as developing a better understanding of the science, the Imperial and Sheffield researchers have been working with Virgin Atlantic and partners, including the Rocky Mountain Institute and Breakthrough Energy, to evaluate how their flight planning process might be adapted to minimise warming contrails. 

"This is science in action – a unique opportunity to gather experimental data and test SAF use at scale. Although only one data point, Flight100 paves the way for gathering more evidence and ultimately working towards a future of more sustainable flying." Dr Marc Stettler Department of Civil and Environmental Engineering

Shai Weiss, Chief Executive Officer at Virgin Atlantic, said: “Flight100 marks an important milestone in aviation’s biggest challenge – decarbonisation. It’s taken radical collaboration and we’re proud to have reached this point, but we need to push further. Alongside fleet transformation, sustainable aviation fuel is the most readily available way for the industry to decarbonise, but we’re facing a lack of supply and price support. For long haul aviation to use 100% SAF on every flight, we need to see action towards creating a UK SAF industry. Flight100 proves that the SAF uptake challenge isn’t operational - if we can make it, we can fly it.”  

Professor Mohamed Pourkashanian, Managing Director for the University of Sheffield Translational Energy Research Centre and Sustainable Aviation Fuels Innovation Centre, which undertook the testing, said: “Carrying out this vital research for Flight100 in partnership with Imperial has been an excellent example of how manufacturers and industry partners can work together with academic institutions to push boundaries and bring innovation to life. Using the facilities at the University of Sheffield Translational Energy Research Centre, including our auxiliary power unit and state-of-the-art measuring and monitoring equipment, we’ve tested the emissions of the fuel for the flight, and determined exactly how the fuels of the future might reduce the impact of flying on the environment. 

“It was great to bring together the resources of two leading energy research universities and take another step towards decarbonising aviation.”  

Professor Mary Ryan, Vice Provost (Research and Enterprise) at Imperial, said: "I'm pleased to see Imperial researchers contributing to a significant moment like this, as part of our commitment to tackling climate change and helping the world transition towards zero pollution. These kinds of big projects, bringing together experts from multiple partners across industry and academia, are key to finding the solutions the world needs. There is still a long way to go to sustainable aviation and we need to continue to think about how and why we travel – but real-world experiments like this can help us better understand the key challenges in transitioning to SAF, and hopefully untangle some of the science around the impact of contrails."

Professor Rafael Palacios, Director of the Brahmal Institute for Sustainable Aviation at Imperial, said: “SAF is the best available solution for long-distance flights that is compatible with a net-zero ambition. This demonstrator,  which is supported by Imperial in the assessment of the non-CO2 impact, is a major step forward in the maturation of this technology.” 

Sustainable aviation fuel 

SAFs are fuels derived from non-petroleum based renewable sources, like waste cooking fats or plant matter, that are capable of being used as a replacement for, or blended with, fossil fuels. When used as fuel and considering their full lifecycle, they emit up to 70% less carbon dioxide than fossil fuels. SAF can also provide a cleaner burning fuel, emitting less particulate matter and therefore form shorter-lived contrails. 

Commercial flights are currently allowed to use fuel comprising up to 50% SAF. This test flight is key in demonstrating that today’s engines, airframes and infrastructure are capable of safely flying using 100% SAF.?The consortium says that this flight, which allows us to explore the operation of 100% SAF in aircraft and infrastructure, is key to the approval of higher blends and reduced climate impact.     

Dr Stettler said: “This is science in action – a unique opportunity to gather experimental data and test SAF use at scale. Although only one data point, Flight100 paves the way for gathering more evidence and ultimately working towards a future of more sustainable flying.”  

The residual emissions of the flight will be mitigated using biochar carbon removals credits, a unique type of offsetting that represents a permanent removal of carbon from the atmosphere.  

SAFs look, smell and function like traditional jet fuel, meaning they can be used in existing aircraft without modifications. Dr Teoh said: “Our research suggests that a fleet-wide adoption of 100% SAF, similar to the fuel used by Flight100, could reduce overall contrail warming effects by 45%. For these reasons, the use of SAF can reduce the climate impact of both CO2 and non-CO2 pollutants.” 

The SAF used in the flight is a unique blend of two different types of SAF. 88% is made from waste oils and fats HEFA produced through the hydroprocessed esters and fatty acids (HEFA) pathway, and 12% is Synthetic Aromatic Kerosene (SAK), made from plant sugars. The plant sugars are derived from corn that is used for food, putting waste starches to use rather than competing with food sources. 

The government’s Jet Zero strategy, published in July 2022 as a roadmap for achieving net-zero aviation, includes SAF as a key consideration.  

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