From the dawn of flight, almost all planes have been powered by fossil fuels. A landmark flight has shown how that could change. On 28 November 2023, a Virgin Atlantic Boeing 787 Dreamliner took off from London’s Heathrow Airport to JFK Airport in New York. In almost every way it was similar to the tens of thousands of flights that day, except for the fact that it crossed the Atlantic fuelled by sustainable aviation fuel (SAF).
Aviation is one of the hardest industries in which to reduce carbon emissions. This is because for all but the smallest aircraft, there are currently few practical alternatives to liquid fuels. Battery-powered planes, for example, are still in the early stages of development and the batteries would need to be smaller and lighter before they could be used on a commercial aircraft.
Meanwhile, more and more people around the world want to fly. By 2040, it is forecast that there could be nearly 8 billion passenger journeys made each year. So, how can the industry handle this growth in air travel without a rise in emissions?
SAF is a term that is generally used to refer to jet fuel that is produced from a proportion of sustainable feedstock as well as conventional fossil fuel feedstocks. SAF is also used to refer to just the sustainable feedstock element. The lifecycle carbon emission savings mentioned in this article relate only to the sustainable feedstock element of the fuel.
In the short to medium terms, SAF will likely be the main route to help decarbonize carbon emissions associated with aviation. The sustainable feedstock portion (SPK) is made from organic materials, such as waste oils, fats, and specialized non-food crops. It’s chemically almost identical to conventional fossil jet fuel, which means it’s compatible with existing engines and infrastructure. It can also be transported using the same trucks and pipelines that transport traditional fuels.
But there is one big difference. The sustainable feedstock element of SAF (i.e. the renewable portion that is mixed with the conventional fossil jet fuel) can typically enable lifecycle carbon emissions savings of up to 80% compared to the conventional jet fuel it replaces.
At the moment, the SAF-fossil-blended fuel accounts for just 0.1% of the jet fuel used in the world. But that’s likely to grow massively in the next few decades, and bp wants to help meet the demand.
That’s why bp worked with Rolls-Royce, Virgin Atlantic and others to supply 56,300 litres of SPK to use in the SAF blend for this boundary-pushing flight. Writing on LinkedIn, Federica Berra, SVP Global Aviation and CEO Air bp said: “It’s really exciting to be on the plane knowing that we helped make history today – the first 100% SAF transatlantic flight by a commercial airline. On the plane are representatives from the consortium and other team members that contributed to making Flight100 happen; the hive of aviation expertise and knowledge from the brilliant people onboard today is quite exhilarating.”
Why was this flight necessary?
Rightly, aviation has some of the strictest safety standards in the world. If you want to introduce a new fuel standard, you need to test, test and test again.
Current regulations state that commercial aircraft can use a maximum of 50% renewable feedstock fuel (SPK) blended with conventional jet fuel. The purpose of this flight was to help build evidence that using 100% renewable content for the fuel is just as reliable – even over 5,000 kilometres of ocean.
The fuel for this flight was a blend of two renewable fuels. Around 88% was SPK. The remainder was synthesized aromatic kerosene (SAK), made from plant sugars, and supplied by Virent. The blend of the two fuels was necessary to ensure the fuel met the aircraft and engine requirements. A lot of science went into this!
But it wasn’t just a question of understanding the chemistry. The bp team developed a detailed plan for every step of the fuelling process, including details on logistics, quality control and safety.
All of this followed extensive trials with sustainable aviation fuel on aircraft powered by Rolls-Royce’s engines – and comes a year after the Royal Air Force took to the skies over Oxfordshire for the UK’s first 100% SAF test flight, for which the SAF was supplied by bp.
So what’s the result? There’s a lot more testing to do – with more flights and more engine types – before using SAF with 100% sustainable feedstock is approved for commercial air travel. But the evidence to date shows that it’s safe – and it works.
What’s next?
Working to help try to enable lifecycle carbon emissions savings associated with aviation is a long-term project. Commercial airlines operate on tight margins, and SAF is currently more expensive to produce than conventional jet fuel. This means the right policies will be essential for mainstreaming its use.
The good news is that in key countries, these are starting to fall into place. And the more bp tests and learns, the more it can bring down costs.
bp thinks SAF is part of the future, and it’s planning to invest in five new biofuels production facilities as part of its ambition to help the world get to net zero.