Virgin Atlantic’s green fuel flight: a retrospective

The green fuel flight

Virgin Atlantic's historic flight on 100% Sustainable Aviation Fuel (SAF) took off from London Heathrow to New York JFK, marking the culmination of a year of radical collaboration, to demonstrate the capability of SAF as a safe drop-in replacement for fossil-derived jet fuel, compatible with today's engines, airframes, and fuel infrastructure.

SAF is strongly believed to have a key role in the decarbonisation of long-haul aviation, providing a pathway to Net Zero 2050. The fuel, made from waste products, delivered CO2 lifecycle emissions savings of up to 70%, whilst performing like the traditional jet fuel it replaced.

While other technologies such as electric and hydrogen remain decades away in aviation, SAF can be used today. Currently, SAF only represents less than 0.1% of global jet fuel volumes and fuel standards allow for just a 50% SAF blend in commercial jet engines. Flight100 proved that the challenge of scaling up production was one of policy and investment, and industry and government needed to move quickly to create a thriving UK SAF industry.

Besides proving the capabilities of SAF, Flight100 assessed how its use affected the flight's non-carbon emissions with the support of consortium partners ICF, Rocky Mountain Institute (RMI), Imperial College London, and the University of Sheffield. The research aimed to improve scientific understanding of the effects of SAF on contrails and particulates and help to implement contrail forecasts in the flight planning process. Data and research were shared with the industry, and Virgin Atlantic continued its involvement with contrail work through RMI's Climate Impact Task Force, which was part-funded by Virgin Unite.

The sustainable aviation fuel

The SAF used on Flight100 was a unique dual blend; 88% HEFA (Hydroprocessed Esters and Fatty Acids) supplied by AirBP and 12% SAK (Synthetic Aromatic Kerosene) supplied by Virent, a subsidiary of Marathon Petroleum Corporation. The HEFA was made from waste fats, while the SAK was made from plant sugars, with the remainder of plant proteins, oil, and fibres continuing into the food chain. SAK was needed in 100% SAF blends to give the fuel the required aromatics for engine function. To achieve Net Zero 2050, the innovation and investment needed across all available feedstocks and technologies had to be harnessed to maximise SAF volumes as well as continuing the research and development needed to bring new zero-emission aircraft to market.

Is it all positive?

Whilst the face value of something like SAF seems great, is it as black and white as it first seems? Is it simply a case of biofuel = sustainable = better, or is there more to it than that?

Despite what the name might lead you to believe, SAF produces equivalent carbon as traditional fuels when burned in flight, however, the key sustainability benefit lies in the greener production of the fuel. However, the key problem lies in whether or not this production is even sustainable in the long term. SAFs are believed to come with a considerable amount of caveats such as high costs of production, negative environmental impacts in production, and limited supply even if up-scaled.

Ramping up SAF production while reducing environmental harm to ensure these fuels are truly sustainable remains the goal. However, most experts agreed that even if SAF production were scaled up, the most promising biofuels in current scenarios are unlikely to provide enough emissions savings to stem aviation’s climate impacts.

Experts consulted for this article largely concur that if Sustainable Aviation Fuels (SAFs) are produced sustainably, using appropriate feedstocks, they can significantly reduce aviation’s heavy emissions burden. By 2050, it is anticipated that these fuels could account for 65% of the sector’s “carbon mitigation”. However, to achieve this, an annual production of 449 billion liters (119 billion gallons) is necessary, as per the International Air Transport Association (IATA). This figure starkly contrasts with the hundreds of thousands of liters produced annually at present.

The fundamental challenge for the sector is obtaining sufficient raw materials to manufacture the most promising fuels at competitive prices. A paper released earlier this year by supersonic aircraft manufacturer Boom Technology optimistically suggests that the SAF industry exhibits early-stage, exponential growth patterns similar to those seen in other renewable energy industries.

A prior review by a researcher at the University of Florence indicated that the massive scale-up of production, investment, and guaranteed availability of a variety of SAF feedstocks — especially those waste streams already utilized by other industries — are hurdles impeding growth. These are sticking points echoed by other experts. An interim target of achieving 10% of aviation fuel from SAFs by 2030 has been set by the industry and national governments, including the U.K. This objective would necessitate the construction of approximately 300 production plants globally.