The International Air Transport Association (IATA) states that sustainable aviation fuel (SAF) can reduce lifecycle carbon emissions by up to 80% compared to conventional kerosene-based fuel. SAF is manufactured using waste-based sustainable feedstocks, including biomass, used fat or oil, municipal waste, and agricultural waste and residues.
SAF is typically blended with up to 50% conventional jet fuel, requiring no aircraft or engine modifications. Currently, commercial and military aircraft, as well as helicopters, can fly with up to a 50% blend of SAF. Aircraft manufacturers, such as Airbus and Boeing, and many airlines worldwide have commenced flights using SAF blended with conventional fuel. It is common for airlines to perform flights with SAF on one of the two engines onboard the aircraft.
The 100% SAF flights
Current 100% SAF flights are such that both engines of a twinjet aircraft use unblended SAF. These are also mostly in the testing phase, conducted mainly by aircraft manufacturers. For example, Airbus conducted its first 100% SAF flight onboard the A350 in November 2021. To ensure that the aviation industry, particularly the narrowbody sector, is ready for the large-scale use of SAF, Airbus conducted another 100% SAF flight onboard the popular A321 aircraft in March.
Various aircraft and engine manufacturers, including Airbus and Rolls-Royce, aim to decarbonize the aviation industry by achieving net-zero carbon emissions by 2050. In October 2022, The ICAO led a two-week negotiation event involving 184 nations to agree on measures to reduce environmental carbon emissions. Some steps include innovative aircraft technologies, optimizing existing commercial flight operations, and increasing production and use of SAF.
How can we achieve completely Net-zero carbon flights?
As mentioned earlier, using unblended 100% SAF on both engines can reduce lifecycle carbon emissions by up to 80%. Assuming that the entire 80% is achieved through SAF, the remaining 20% still exists. Eliminating the remainder is often done by offsetting carbon emissions in methods not pertaining to the specific flight. For example, airlines such as Etihad Airways have achieved net-zero flights by using SAF across multiple flights to a particular destination or a flight corridor.
The first ever net-zero transatlantic flight will commence between London and New York later this year. A Virgin Atlantic Boeing 787 powered by Rolls-Royce Trent 1000 engines is expected to perform a net-zero flight. According to Shai Weiss, the CEO of Virgin Atlantic,
“This challenge recognises the critical role that SAF has to play in decarbonising aviation and the urgent collective action needed to scale production and use of SAF globally. The research and results will be a huge step in fast tracking SAF use across the aviation industry and support the investment, collaboration and urgency needed to produce SAF at scale. Our collective ambition of Net Zero by 2050 depends on it.”
The sole source of fuel for the flight will be unblended SAF. Additionally, the company will use biochar carbon credits to achieve further carbon removal. Biochar traps and stores carbon from the atmosphere through a permanent sequestration process. This process physically traps carbon in a stable form for long periods.
With the biochar method, carbon removal is quantified and verified for its quality. While the sole use of SAF can only offset carbon emissions by a certain percentage, combining it with the biochar credits can facilitate true net-zero flight.