Last week marked a milestone in aviation as the world’s first transatlantic flight using sustainable aviation fuel (SAF) took off from London Heathrow and landed at New York JFK.
This Virgin Atlantic Boeing 787, named Flight100, demonstrated the potential of using SAF on long-haul flights, replacing jet fuel and playing an important role in decarbonizing the aviation industry.
It was the result of more than a year of collaboration between a Virgin Atlantic-led consortium including the University of Sheffield, Imperial College London, Boeing, Rolls-Royce, BP and others, and was partly funded by the UK Department for Transport.
Researchers from the University of Sheffield worked with their colleagues at Imperial College London to test and evaluate SAF. The team measured particulate matter emitted by a smaller aircraft engine and confirmed that SAF reduces the amount of carbon dioxide emissions by up to 70% compared to conventional jet fuel. We spoke to Prof Mohamed Pourkashanian, Director of the University of Sheffield Energy Institute and Sheffield’s Director, who was on the flight. Excerpts:
What does SAF consist of?
These are advanced fuels made from renewable sources, waste or recycled sources instead of fossil fuels extracted from the ground. Compared to traditional fossil aviation fuel, SAF can achieve emissions savings of up to 70% on a life cycle basis.
The SAF used on Flight100 was a blend of 88% HEFA (hydrogen processed esters and fatty acids) from AirBP and 12% SAK (synthetic aromatic kerosene) from Virent, a subsidiary of Marathon Petroleum Corp.
HEFA is made from waste fats while SAK is made from plant sugars, while the rest of the plant proteins, oils and fiber enter the food chain.
SAK is required in 100% SAF blends to provide the fuel with the aromatics required for engine function.
Researchers from the University of Sheffield worked with their colleagues at Imperial College London to test and evaluate SAF.
Researchers from the University of Sheffield worked with their colleagues at Imperial College London to test and evaluate SAF.What carbon emissions were produced during this test flight?
The total carbon emissions from this flight are currently being studied by another member of the consortium, which will publish its results soon.
Did the Boeing 787 aircraft that used SAF require mechanical changes?
No, SAFs work like traditional jet fuel, meaning they can be used on existing aircraft without modifications.
What engine powers this particular Boeing 787?
This aircraft is powered by a Rolls-Royce Trent 1000 engine.
This was the first long-haul flight to use SAF? Does this mean SAF will be used on short-haul flights?
SAF has been used safely in other demonstration flights; However, Flight100 is the longest flight ever with 100% SAF. It is the first time a commercial airline has used 100% SAF in both engines on a long-haul flight. Specifically, this was the first long-haul flight in which both engines were used at 100% SAF. Previous transit aircraft typically used up to 50% SAF or just one engine at 100%.
The currently maximum permitted mixing ratio for SAF is 50%. The 100% SAF flight across the Atlantic will expand the evidence base for the use of 100% SAF and demonstrate the longer-term potential of a SAF industry to decarbonize aviation.
Did Flight100 have passengers?
It was a non-commercial demonstration flight with no paying passengers or cargo. The flight was operated with a permit to fly issued by the British CAA. This includes permission to carry on board a number of observers who are critical to the project and critical to the success of the flight. The observers on board included consortium members, political representatives, media and industry partners who were expected to play a role in the further development of the SAF.
How much does SAF cost compared to traditional kerosene?
Currently SAF is more expensive than kerosene. The price depends on the production route. The HEFA route is the cheapest and the power-to-liquid route is the most expensive. However, this could change if the price of green hydrogen is reduced through projects like the US Hydrogen Shot. The price comparison between kerosene and SAF would change if there was a carbon pricing system or subsidies.
Even a partial admixture of SAF in engines can make a big contribution to low-carbon travel. Are you aiming for aircraft operating at full SAF? Could there be pressure from oil companies against SAF?
Global government policies (US IRA, UK 10% mandate and EU mandate) all call for 10% SAF by 2030. There is great opportunity here for oil companies to get involved in co-processing. Oil companies can use their facilities/refineries to convert hydrocarbons produced from sustainable sources into SAFs.
SAF achieves average savings in greenhouse gas emissions of up to 70% over the entire life cycle compared to kerosene.
SAF can help reduce the impact of air travel on the environment in both the short and long term.
Can SAF also be used in the automotive industry (passenger cars and commercial vehicles)?
There are already a number of technologies that can help reduce the automotive industry’s impact on the environment, such as electric vehicles and the emerging development of hydrogen as a fuel. However, decarbonizing aviation poses a greater challenge. SAFs are aimed at the aviation industry.
By-products of SAF production can be used to fuel ships as part of the optionality strategy, for example as biodiesel. Road transport is not such a difficult sector to decarbonise as electrification and hydrogen/fuel cells will solve this problem.
While doing this project with Boeing, did Airbus also show interest in SAF?
Airbus published information about SAFs in a post on its website, noting that SAF is one of the aerospace industry’s best decarbonization solutions, capable of being used in both operating fleets and the aircraft of tomorrow.