Can green jet fuel take off fast enough?

More than 100 airlines have started using sustainable aviation fuels (SAFs). But can the new fuels be scaled fast and cheap enough to meet future demand? Keystone / Silva Schnurrenberger

A Swiss start-up aims to produce clean jet fuel from renewable methanol. But while the promising technology is attracting airlines, investors and policymakers, a critical challenge remains: can sustainable aviation fuels be scaled fast and cheap enough to decarbonise global air travel?

In late August the Paul Scherrer Institute (PSI) and Swiss start-up Metafuels inaugurated the world’s first methanol-to-jet fuel demonstration plant at the institute’s campus in Villigen, canton Aargau.

The demonstration plant in Villigen produces just 50 litres of clean jet fuel a day, compared with roughly 4,000 litres of fuel burned on a London-Zurich flight, but Metafuels hopes it will serve as a proof-of-concept to attract funding for larger facilities. Simon Bradley, Swissinfo

“Sustainable aviation fuel is the single most important lever we have to decarbonise aviation,” declared Metafuels CEO Saurabh Kapoor at the inauguration event.

The pilot plant converts renewable methanol, made from green hydrogen and captured carbon dioxide (CO₂), into synthetic jet fuel. Recently certified for aviation use, it can cut lifecycle emissions – across manufacturing, transport and flight operations – by up to 90% compared with fossil kerosene and can be used in existing aircraft.

Until recently, synthetic jet fuel was largely confined to laboratories. Today, certified fuels are entering commercial aviation, meaning the industry’s biggest challenge is no longer proving the technology works but whether it can be produced at sufficient scale in time and at an affordable cost.

Why the Swiss approach is different

Aviation accounts for roughly 2-3% of global CO₂ emissionsExternal link and is among the fastest-growing sources of greenhouse gases. Because long-haul flights cannot yet be electrified, sustainable aviation fuels (SAF) – and ultimately synthetic e-fuels like the one by Metafuels – are widely seen by the aviation industry as the main decarbonisation pathway, potentially delivering up to 65% of emissions reductions by 2050.External link

According to the World Economic Forum,External link the US leads commercial deployment, China is rapidly expanding capacity and Europe is at the forefront of policy-driven innovation in advanced fuels.

SAF can be produced from various sources. More than 80% of SAF currently comes from waste oils and fats, but limited supplies have shifted attention to e-SAF made from renewable electricity, hydrogen, and captured CO₂.

Metafuels combines green hydrogen, generated via water electrolysis using renewable power, with captured CO₂ from biogenic sources (plants, wood or waste) or direct air capture to create green methanol. A catalytic process then converts the methanol into synthetic kerosene chemically identical to conventional jet fuel.

Illustration: Kai Reusser, Swissinfo

Camille Mutrelle, a clean aviation expert at the Brussels-based NGO Transport & Environment,External link says methanol-to-jet fuels stand out because they can be made using renewable hydrogen and captured CO₂, rather than sources with limited availability like waste oils or agricultural crops, making larger-scale production possible.

“Methanol-to-jet is not a silver bullet,” Mutrelle told Swissinfo, but she sees it as one of the most promising e-fuel technologies for helping the aviation sector cut emissions over the long term.

Can production keep up?

Metafuels is developing its first industrial-scale plant in the Dutch port of Rotterdam, aiming to produce 10 tonnes of fuel per day by 2028 and 1,000 tonnes per day by the mid-2030s.

Achieving net-zero aviation by 2050 is expected to require around 500 million tonnes of SAF annually.External link Without stronger incentives, supply is unlikely to match the industry’s climate goals, says the International Air Transport Association (IATA).

Global output will reach just 2.4 million tonnes in 2026. Production volumes are “disappointing”, far below what will be needed to decarbonise air travel, IATA Director General Willie Walsh saidExternal link in June. He blamed weak government policies and insufficient investment from major oil firms.

Experts also warn that many announced projects never reach production.

“Of the SAF production capacity announced as expected to be operational by the end of 2026, our recent analysisExternal link found that only 24% had been completed, while 26% had been paused or cancelled,” Alessandro Martulli, environmental economics researcher at Hasselt University, told Swissinfo. He said project announcements are an unreliable guide to future supply because many never proceed to construction.

Whether Metafuels succeeds depends on overcoming the wider industry challenges: high production costs, financing and access to renewable energy and feedstocks.

Multiple obstacles

Scaling SAF remains constrained by cost, energy and resource requirements. Sustainable jet fuel presently costs two to six times more than fossil keroseneExternal link, depending on the production pathway.

Producing synthetic fuels requires vast amounts of renewable electricity, green hydrogen, water and CO2. A 2025 report by consultancy EYExternal link estimates that between $1 trillion to $1.5 trillion must be invested in SAF production by 2050 to reach net zero.

Mutrelle argues the biggest bottleneck is not technology but a lack of commitment from major fuel suppliers.

“The oil and gas sector clearly possesses the necessary capital. Europe has over 40 planned industrial e-SAF projectsExternal link, yet not a single one has reached a Final Investment Decision,” she said. Fuel suppliers who have to meet quotas under Europe’s ReFuelEUExternal link regulation have been slow to commit to the long-term purchase agreements needed to unlock investment, she added.

Martulli points to rising project costs, limited competitiveness of SAF, and shortages of key inputs such as affordable green hydrogen and biogenic CO₂.

Is regulation ahead of reality?

More than 100 airlines have started using SAFs. Swiss International Air Lines (SWISS) currently uses it for 0.9% of its fuel consumption, all of it produced from biogenic residues such as used cooking oilsExternal link. To secure future supplies, it has partnered with Metafuels and another e-SAF producer, ETH Zurich spinoff Synhelion.

“As a customer we are basically ready and could be transformed tomorrow if there was enough sustainable fuel available at the right price,” Jens Fehlinger, CEO of SWISS, told attendees at the recent Metafuels/PSI inauguration event.

Under EU rules, airlines must gradually increase SAF use, reaching 70% by 2050. Switzerland has aligned its revised CO₂ Act with the same targets.

Some industry observers fear regulators are mandating aviation decarbonisation faster than production can keep up, risking higher fares.

“The 2030 e-SAF targets by the UK and the EU are beyond unrealistic,” says Marie Owens Thomsen, IATA’s Senior Vice President Sustainability and Chief Economist. IATA notes that the EU and the UK will require about 0.6 million tonnes of e-SAF by 2030, while current operating and under-construction capacity amounts to only 0.02 million tonnes.

Switzerland and SAF

The Metafuels e-SAF project at PSI has been several years in the making and follows on the heels of the Swiss sustainable fuel start-up Synhelion, which was born out of research at the federal technology institute ETH Zurich.

Switzerland is positioning itself as an advanced research hub for next-generation fuels, backed by funding and top research institutes. Metafuels received CHF4.4 million in funding from the Swiss Federal Office of Energy. Under the new CO2 act, the Swiss government has set aside CHF390 million up to 2030 to support future projects that reduce greenhouse gas emissions in the aviation sector, with a focus on renewable synthetic aviation fuels.

“Switzerland won’t be a volume producer of SAF. But we are the place where the technology is invented, de-risked, and exported. That creates climate value and economic value,” says Francine Zimmermann, director general of the Swiss Federal Office of Civil Aviation (FOCA). 

“For the non-e-SAF component of the European mandate, announced capacity could, in principle, be sufficient by 2030,” said Martulli. But e-SAF remains a major concern, with only a small fraction of proposed EU production projects progressing to a final investment decision, threatening future supply targets.

Despite these concerns, the researcher says the targets remain achievable if governments reduce investment risks and provide long-term support and certainty, as they did for wind and solar power.

IATA saysExternal link accelerating SAF adoption will require coordinated action to expand renewable energy and  supply of fuel sources, ensure open access to fuel infrastructure and strengthen policy and investment frameworks, as well as creating a global SAF market.

Yet e-SAF remains scarce, and some experts argue technology alone cannot offset continued growth in air travel.

“Our studies at [the Paul Scherrer Institute] have shown that SAF will not be enough. We also have to reduce the number of flights,” said Marco Ranocchiari, head of energy system integration at the institute.

As companies such as Metafuels race to scale synthetic fuel production, the next few years will test whether policy, technology and investment can bridge the gap between climate ambitions and the realities of aviation growth.

Edited by Gabe Bullard/Veronica De Vore