Sustainable Skies Will Require Much More Than SAF

The quest to reduce carbon emissions and find a sustainable flightpath for the civil aviation industry in coming decades remains in a state of flux.

Although progress has been made, notably the burgeoning scale up of sustainable aviation fuel (SAF) production, inconsistency in individual governments’ policies and investment continues to exert a drag on projects aiming to reduce aviation’s effect on climate change.

At the Sustainable Skies World Summit 2025 in Farnborough, UK, in May, several hundred representatives of airlines, SAF fuel producers, governments and research institutions debated the state of the industry’s commitment to being carbon net zero by 2050.

The UK government’s announcement of a revenue certainty mechanism (RCM) to encourage investment in SAF plants was a positive in a sea of uncertainty about how and when the industry will meet its goals. The RCM will operate via a guaranteed strike price in which SAF producers will be paid a fixed price, regardless of whether the market price dips below that level.

The UK government said it believed that the RCM, alongside the country’s newly introduced SAF Mandate, the Advanced Fuels Fund and its industrial strategy, would provide a launchpad to drive growth and investment in the sector.

This support was important, several speakers said, as it provided potential private investors with confidence to invest in a sector where the technology was still immature.

“Countries are slowly developing their individual policies on increasing the use of SAF, and sometimes it pays to pause slightly and take stock,” Qantas chief sustainability officer Fiona Messent said. “Twelve to 24 months ago, we were lamenting the lack of policy [in Australia]. But today, we’re quietly thankful that we’ve taken the time to see what works around the world. It’s been really useful to see what works, and what doesn’t, in places such as the UK and European Union.”

Qantas, Sydney Airport and Australian fuel retailer/refiner Ampol, supported by Qantas’ SAF Coalition partners, marked the largest-ever commercial importation of SAF into Australia—nearly 2 million liters of unblended SAF—in May. The fuel was imported by Ampol from Malaysia for blending with conventional kerosene before testing and certification, prior to distribution into Sydney Airport’s supply chain. Blended at a ratio of approximately 18%, the fuel could power the equivalent of 900 flights from Sydney to Auckland, New Zealand, on Qantas and Jetstar’s Boeing 737s, the Australian flag-carrier said.

The airline industry has warned for years that the high cost of SAF risks making tickets unaffordable. However, the small percentages of SAF being incorporated into fuel uptakes over the next decade or so means that any fare rises would be “a very digestible amount of money,” SAF producer Zaffra CEO Jan Toschka told the audience.

The sense of uncertainty in the aviation market has been heightened by moves by Airbus and Boeing to pull back from new-generation designs. Airbus is sliding back the expected arrival of a new hydrogen-powered aircraft, while Boeing has paused development of the X-66 truss-braced wing design.

Additionally, major fuel producers have gone cool on biofuels. BP is scaling back research on alternative fuels in the face of activist shareholders that want to focus on the bottom line, and Shell has paused construction of a new biofuel plant in Rotterdam, Netherlands.

CONTRAILS

The past few years have seen increasing attention and research paid to “contrail avoidance” but questions remain. American Airlines chief sustainability officer Jill Blickstein said flight plans aimed at avoiding altitudes where contrails form can have their own problems. “We’re getting turned down by air traffic control (ATC) more than we would expect,” she said, stressing this was not arbitrary but often linked to genuine issues like airspace congestion.

Additionally, software aimed at avoiding contrails sometimes gives flight plans that pilots would not accept because of unrealistically steep climbs or descents, Blickstein said, and avoiding contrail-generating altitudes can place airliners in areas of air turbulence.

Airspace modernization has been proposed as an efficiency measure to cut emissions, but speakers admitted that this type of development had not moved as quickly as required to offset the growth of airline fleets.

“At the moment, the way we’re doing it just takes too long—that’s my frustration,” UK ATC provider NATS sustainability, health and safety director Ian Jopson said.

Speakers noted that polling of airline passengers consistently shows climate change as being a high priority for travelers, despite resistance at having the cost of sustainability reflected in ticket prices.

Meanwhile, there is a “huge amount of uncertainty” as to whether the UK aviation sector can hit its environmental targets, UK regulator CAA’s sustainability head Harry Armstrong said. It would be “incredibly hard” to meet future emissions targets, especially with the UK government’s agenda of stimulating economic growth. Asked whether the UK government understood that “pushing in one direction causes problems in another,” Armstrong said he believed ministers accepted the potential dichotomy and were determined that economic growth had to be sustainable.

Talking on the sidelines of the event, Armstrong said that the level of uncertainty as to whether the UK could hit its targets arose “because you’re reliant on so many actors and so many things that need to happen” in areas such as infrastructure, sustainable fuel feedstocks, and research and development (R&D).

Meanwhile, SAF would only take the airline industry so far and zero-emission flight (ZEF) required much more attention, Fathom Consulting head of energy and climate Brian Davidson said.

“ZEF needs a lot of R&D, especially cutting-edge R&D, and Europe isn’t doing nearly as much as the US,” he said. ZEF had high upfront costs including R&D, certificating new aircraft and installing new airport infrastructure, he added, but it made strong economic sense for policymakers to support the complex R&D required to make ZEF a reality because of the wider economic benefits.