Virgin Atlantic just operated the world's first transatlantic flight using 100% sustainable aviation fuel. Here's why critics aren't convinced it's game-changing.

• Virgin Atlantic Airways flew a Boeing 787 across the Atlantic in November using 100% SAF.
• The world first comes as airlines push biofuels as an effective way to decarbonize aviation.
• Critics are not convinced the industry can produce enough SAF by 2050 to make an impact.
• This article is part of "Future of Sustainable Aerospace," a series exploring the industry's green trends. 

Virgin Atlantic Airways just operated "Flight100" — the world's first transatlantic commercial flight using 100% sustainable aviation fuel, flying a Boeing 787 Dreamliner from London's Heathrow Airport to New York's JFK Airport with a mix of two different biofuels.

These included 88% HEPA — hydroprocessed esters and fatty acids — made from waste fats, and 12% synthetic aromatic kerosene, or SAK, made from plant sugars. Virgin said SAK makes 100% SAF possible because it produces the required aromatic compounds needed to meet engine-performance requirements.

This same SAK fuel allowed United Airlines to perform its one-off operation in December 2021 when it flew the world's first passenger flight using 100% SAF in one engine.

Current standards only allow up to 50% SAF in commercial jet engines, though Virgin received special permission to operate Boeing's Rolls-Royce Trent 1000 engines on the greener fuel. There were no paying passengers on the flight.

The historic trek comes as dozens of international regulators push to decarbonize the aviation industry and achieve net-zero CO2 emissions by 2050.

Along with building more efficient aircraft and engines, SAF has become a key factor in this industry goal. Forty global airlines, including United, Lufthansa, Air France, and Australia's flag carrier Qantas, have all invested in biofuels, according to the International Air Transport Association, or IATA.

Aviation makes up about 2% of global emissions, according to the International Energy Agency. But the IATA estimates that SAF could contribute to 65% of reduced aviation emissions by 2050.

With a strong focus on sustainability amid the age of "flight shaming" and rising climate-crisis concerns, some experts see Virgin's milestone flight as a significant step forward in the SAF market.

"I think the Virgin flight is really exciting because it shows it can be done," Andy Williams, a senior associate at law firm Reddie & Grose and former in-house attorney at General Electric, told Business Insider. "The advantage of this kind of fuel is that it will be a direct replacement, so you don't have to go to the expense of radically changing the engine design. That's the good thing about SAF."

Commenting on Virgin's public display of SAF capabilities, Richard Branson, the founder of Virgin Group who was on board the flight, boasted the airline's "pioneering spirit" and ability to question the "status quo."

"The world will always assume something can't be done until you do it," he said. "The spirit of innovation is getting out there and trying to prove that we can do things better for everyone's benefit."

Despite Branson's optimism, the UK does not currently have any commercial SAF plants available — one factor greatly limiting SAF production, though the government said it plans to start construction on five plants by 2025.

This lack of infrastructure, combined with costs and other supply-chain factors, has prompted critics to cast doubt on the industry's ability to mass produce the needed amount of SAF by 2050.

Critics are not convinced SAF is a realistic solution

Since Virgin announced its 100% SAF flight, experts and climate activists have debated what it means for the industry.

According to data from the accounting firm KPMG, a surge in SAF supply is expected by 2030 thanks to continued investment in this "waste-to-fuel production," but the market will still be limited due to factors such as feedstock constraints.

The firm also noted that future SAF mandates could outrun supply, forcing prices to further spike and turn off buyers. The high cost of biofuels is already one major obstacle facing airlines, which have argued that using SAF could lead to higher fares for customers.

Some activists have even taken a jab at Virgin, suggesting Flight100 represents an unrealistic way to decarbonize aviation.

"Unfortunately, running a plane on alternative fuels is less of a breakthrough and more of a gimmick," Alethea Warrington, a senior campaigner at the climate charity Possible, told BI, noting the immense cost and resources needed to meet the industry's 2050 net-zero goal.

Leah Ryan, the managing director at the advisory firm Alton Aviation Consultancy's Dublin office, shared data with BI that shows where the industry's SAF production needs to be in the next 26 years to make an impact.

According to the data, 500 flights used SAF in 2016. By the end of 2022, that number jumped up to 450,000 flights.

Converting that to volume, 80 million liters, or 2 million gallons, and 150 million liters, or 40 million gallons, of SAF were used in each respective year, Ryan said.

"The big takeaway is if we consider IATA's net-zero goal and its estimate that SAF could account for 65% of all the carbon migration in 2050, that would require an annual production of 450 billion liters of SAF — that's billions," Ryan told BI, noting that SAF only amounts to 0.1% of all fuel airlines consume today.

Data from IATA shows the same multibillion-liter number, noting the industry spent up to an estimated $510 million extra on SAF in 2022.

Ryan reiterated to BI that the lack of resources and the high costs of producing SAF drive its slow development: "We know we have to do this, but what does it mean for us and is it even going to be in our lifetime?"

Virgin has acknowledged the industry's SAF-production challenges

After Flight100 took off from London, Shai Weiss, the CEO of Virgin, acknowledged that "there's simply not enough SAF" available. He further said significant financial support and government backing are imperative in moving the needle.

According to the Air Transport Action Group, around 40 countries already have or are considering implementing SAF-related policies.

In the EU, regulators have passed the "RefuelEU aviation initiative" to kickstart the SAF market by placing obligations on fuel suppliers and EU airports regarding biofuel distribution and access.

For the US' part, the Biden administration's "Sustainable Aviation Fuel Grand Challenge" has set a goal to produce at least 3 billion gallons of SAF a year by 2030.

In an IATA report published on Wednesday, the organization said SAF production is estimated to hit 1.875 billion liters, or 495 million gallons, in 2024, up from 625 million liters, or 165 million gallons, in 2023.

But according to Williams, getting regulators and the general public to support SAF is going to be a tough road.

"The whole planet is so wedded to the use of fossil fuels, and they're still readily available — it's not like someone has turned off the tap," he told BI. "Human beings like taking the easy way out, and if they can avoid making a difficult decision, they will. It's human nature."