What Is Sustainable Aviation Fuel and Why SAF Matters
Aviation accounts for roughly 2 – 3% of global carbon emissions, and that share is expected to rise as air travel grows (IAE). Sustainable Aviation Fuel (SAF) is widely regarded as the most immediate tool to reduce aviation’s climate impact. Unlike traditional jet fuel, which is derived entirely from fossil resources, SAF is produced from renewable or waste-based feedstocks and can cut lifecycle emissions by up to 70% compared to conventional jet fuel.
SAF is central to the aviation industry’s net-zero by 2050 commitment, endorsed by the International Civil Aviation Organization (ICAO) and industry leaders worldwide. The problem? Volumes. Today, SAF makes up less than 1% of global jet fuel supply (IATA). High costs and limited availability remain the main hurdles. Industry coalitions are pushing for wider adoption by accelerating investment, improving policy support, and expanding production capacity.
There are currently seven ASTM-certified production pathways for SAF, each converting different feedstocks into drop-in jet fuel. Among the most prominent are:
Hydroprocessed Esters and Fatty Acids (HEFA): the most commercially advanced, made from used cooking oil, waste animal fats, and other lipids.
Fischer – Tropsch (FT): converts biomass into syngas, then liquid fuels.
Alcohol-to-Jet (ATJ): converts ethanol or isobutanol into jet fuel.
Together, these technologies give SAF flexibility in sourcing while ensuring the end product is chemically identical to fossil jet fuel, certified under ASTM D7566.
For now, SAF is approved for use in blends of up to 50% with conventional jet fuel, although the first test flights on 100% SAF have already taken place in the U.S. and Europe. Moving toward 100% certification will be critical for unlocking SAF’s full decarbonization potential.
How Jet Fuel Is Made and Why Feedstocks Matter
To understand what makes SAF different, it helps to start with how conventional jet fuel is produced. Jet A/A‑1 fuel, the standard for commercial aviation, is refined from crude oil. At oil refineries, crude is separated into different fractions through distillation. The kerosene fraction is then treated and upgraded to meet strict performance and safety standards required for aviation. In short, petroleum feedstocks go in, jet fuel comes out.
With SAF, the process is similar, but the feedstocks are different. Instead of starting with fossil crude dug up from the ground, producers begin with renewable or waste-based feedstocks – carbon that’s already in the atmosphere – such as used cooking oil and waste fats, ethanol or other alcohols, municipal solid waste or biomass, and even captured carbon from the air.
These feedstocks are converted into synthetic hydrocarbons that are then upgraded into drop-in jet fuels chemically indistinguishable from petroleum jet fuel, but with significantly lower lifecycle carbon intensity.
A Brief History of SAF Technology and Production
The development of SAF dates back to the early 2000s, when concerns about aviation’s climate impact began gaining global traction. As the industry acknowledged its dependence on fossil-based kerosene and its growing share of greenhouse gas (GHG) emissions, research turned toward alternative aviation fuels. Inspired by the success of bioethanol and biodiesel in ground transport, early programs explored whether renewable resources could power aircraft, laying the foundation for today’s SAF pathways.
The first major milestone arrived in 2008, when Virgin Atlantic operated the world’s first commercial flight using a biofuel blend – a proof point that aviation biofuels were technically viable. Over the next decade, airlines and aircraft manufacturers launched a series of SAF demonstration flights. In 2018, Virgin Atlantic’s VS16 flight from Orlando to London Gatwick became the first transatlantic flight powered by ATJ SAF, produced by LanzaJet’s technology. That same year, All Nippon Airways (ANA) completed the first transpacific flight fueled by recycled-carbon ATJ SAF, also using the LanzaJet pathway.
Since then, SAF has moved from demonstration to integration. Over half a million flights worldwide have now used SAF blends (KMPG), supported by fuel suppliers, airports, and airlines aligning with ambitious climate goals set by the ICAO, International Air Transport Association (IATA), and national governments. Research and investment continue to broaden the feedstock base – from waste oils and agricultural residues to municipal solid waste and captured CO₂ – expanding the potential supply of low-carbon aviation fuels.
Technology #1: Hydroprocessed Esters and Fatty Acids (HEFA)
The HEFA pathway was the first to achieve commercial-scale production of SAF and remains the most widely deployed process today. HEFA converts waste oils and fats, such as used cooking oil, animal fats, and certain vegetable oils, into renewable hydrocarbons that can be refined into drop-in fuels like SAF and renewable diesel. Because it leverages existing refining infrastructure, HEFA has scaled more rapidly than other pathways and is the dominant source of SAF currently available on the market.
The process begins with pre-treatment of fats and oils to remove impurities. These feedstocks are then hydroprocessed with hydrogen in the presence of catalysts. This step removes oxygen atoms, leaving hydrocarbon chains that are chemically almost identical to fossil-derived jet fuel. The hydrocarbons are then isomerized and distilled to meet the stringent performance and safety specifications required for aviation. In practice, the resulting HEFA-based SAF is virtually indistinguishable from conventional jet fuel, yet it can deliver significant lifecycle greenhouse gas reductions when sourced from truly sustainable feedstocks.
Despite its maturity, HEFA faces important challenges. The process is feedstock-constrained: the global availability of used cooking oil and waste fats is limited, and in some regions, demand has already outpaced supply. As a result, HEFA is often viewed as a bridge solution, critical for building SAF supply chains in the near term, but unlikely to scale alone to meet long-term aviation decarbonization goals.
For these reasons, industry stakeholders are investing heavily in next-generation SAF pathways – including Alcohol-to-Jet (ATJ) and Fischer – Tropsch (FT) – which can use a broader range of feedstocks, from municipal solid waste to captured carbon. These alternative routes are expected to complement HEFA over time, expanding both the feedstock base and the potential scale of SAF production.
Technology #2: Fischer-Tropsch (FT)
The FT pathway is one of the most versatile and technically mature routes for producing SAF. At its core, the FT process converts carbon-rich feedstocks — including biomass, municipal solid waste, forestry residues, or even natural gas — into liquid hydrocarbons that can be refined into drop-in jet fuel.
The process begins with gasification, in which solid or gaseous feedstocks are broken down at high temperatures to create syngas, a mixture of hydrogen (H₂) and carbon monoxide (CO). This syngas is then subjected to the FT catalytic reaction, which rearranges the molecules into longer-chain hydrocarbons. These hydrocarbons undergo upgrading through hydrocracking, isomerization, and distillation until they meet the strict performance standards of aviation fuel. Because the end product is chemically nearly identical to conventional kerosene, FT-based fuels can be blended seamlessly into existing jet fuel supply chains without modifications to aircraft or infrastructure.
A key advantage of the FT pathway is its feedstock flexibility. Unlike the HEFA pathway, which depends heavily on limited waste oils and fats, FT can utilize abundant resources such as woody biomass, MSW, or agricultural residues, making it attractive from a scalability perspective. Some projects are even exploring FT production from captured CO₂ combined with green hydrogen, which could unlock near-zero-carbon “electrofuels.”
However, FT also presents significant challenges. The process requires large-scale gasification plants, heavy capital investment, and high energy inputs. The overall carbon intensity of FT-based SAF is highly dependent on the type of feedstock used and the source of energy for gasification. For example, using biomass with renewable electricity can deliver deep emissions reductions, while relying on fossil feedstocks like natural gas risks undermining climate benefits.
In practice, FT is often seen as a high-potential but capital-intensive pathway. It could play a critical role in expanding SAF supply, especially in regions with abundant biomass or waste resources, but its long-term climate impact hinges on consistent use of sustainable feedstocks and low-carbon energy inputs. For this reason, ongoing R&D and demonstration projects, often backed by governments and international energy agencies, are exploring ways to improve efficiency, reduce costs, and scale FT technology for aviation.
Technology #3: Alcohol-to-Jet (ATJ)
The Alcohol-to-Jet (ATJ) pathway is an emerging but highly promising technology for producing SAF. In this process, alcohols such as ethanol or isobutanol are converted into jet-range hydrocarbons through a series of steps:
Dehydration – alcohol is dehydrated to form olefins.
Oligomerization – these olefins are combined into longer hydrocarbon chains.
Hydrogenation and Fractionation – the resulting molecules are hydrogenated and upgraded into drop-in jet fuel that meets ASTM D7566 specifications for aviation use.
Often referred to as the ethanol-to-SAF pathway, ATJ has strong potential because it leverages one of the world’s most widely produced bio-based intermediates: ethanol. Ethanol is already manufactured at scale from diverse feedstocks – corn, sugarcane, cellulosic biomass, municipal solid waste, and other waste-carbon sources – making it a flexible and abundant input for renewable jet fuel production.
One of ATJ’s greatest advantages is its scalability. Global ethanol production exceeds 31 billion gallons per year, supported by well-established agricultural supply chains and processing infrastructure. And, today’s ethanol is much more sustainable fuel than it used to be. Over just the past decade, producers have boosted ethanol yields per bushel by nearly 10% (farmdoc daily) while cutting lifecycle greenhouse gas emissions by more than 20% (ANL). With regenerative farming and carbon capture, reductions of up to 70% are possible, making ethanol not only abundant, but also a rapidly improving low-carbon feedstock.
By redirecting a fraction of global ethanol capacity toward SAF, ATJ could help address the industry’s urgent need for larger-scale fuel alternatives. Because ethanol can be produced from waste biomass, agricultural residues, and non-food feedstocks, the pathway also offers strong sustainability benefits and avoids direct competition with food crops.
The flexibility of ATJ makes it particularly important in the broader SAF landscape. While HEFA and FT pathways face constraints related to limited waste oils or the capital intensity of large-scale gasification, ATJ can draw from the global bioethanol industry and adapt to local feedstock availability. Ongoing innovation, such as improving conversion yields, expanding to advanced cellulosic ethanol, and integrating carbon capture, is expected to enhance the economic and environmental performance of ATJ fuels.
In this sense, ATJ represents not only a near-term bridge to accelerate SAF deployment but also a long-term cornerstone pathway. With supportive policy frameworks (such as the U.S. Inflation Reduction Act and ICAO’s CORSIA scheme) and investment in commercial-scale facilities, ATJ has the potential to transform renewable ethanol into sustainable aviation fuel at volumes that can meaningfully reduce aviation’s carbon footprint.
LanzaJet’s Technology Leadership
LanzaJet has quickly established itself as a leading innovator in the SAF space, with its proprietary Alcohol-to-Jet (ATJ) technology at the core of its strategy. Founded in 2020, the company’s mission is to decarbonize aviation by delivering low-carbon, drop-in alternatives to fossil jet fuel. Unlike many early-stage SAF companies, LanzaJet has already attracted significant backing from airlines, fuel producers, corporate partners and government bodies, positioning it as one of the most commercially viable players in this rapidly scaling market.
At the heart of LanzaJet’s platform is its ATJ conversion process, which transforms ethanol produced from renewable feedstocks such as energy crops, agricultural waste, sugarcane, industrial off-gases, or municipal solid waste into jet-range hydrocarbons. The process begins with ethanol dehydration into ethylene, followed by oligomerization and hydrogenation to yield hydrocarbon chains that meet ASTM jet fuel specifications. Because ethanol is produced at massive global scale, the ATJ pathway offers both feedstock flexibility and scalability, making it more adaptable than SAF processes constrained by limited waste oils or energy-intensive processes. Importantly, the output is a drop-in fuel that requires no modifications to existing aircraft engines or fueling infrastructure, enabling immediate deployment at scale.
What sets LanzaJet apart is its ability to move from technical innovation to real-world deployment. The company’s Freedom Pines Fuels facility in Georgia, the world’s first commercial-scale ATJ plant, is expected to produce annually 9 million gallons of SAF and 1 million gallons of renewable diesel – a great source of energy for data centers’ backup generators. Beyond production, the project demonstrates that ethanol-to-SAF can transition from pilot-scale research to industrial reality, providing a replicable blueprint for global deployment.
Looking ahead, LanzaJet is positioned to be a cornerstone of the global SAF market. Its technology can integrate into existing ethanol supply chains worldwide, from U.S. corn ethanol to Brazil’s sugarcane ethanol and emerging cellulosic ethanol markets. With growing policy support through mechanisms like the Inflation Reduction Act, EU ReFuelEU Aviation mandate, and ICAO’s CORSIA scheme, the company is well-placed to accelerate SAF adoption at the scale aviation needs.
By bridging proven ethanol infrastructure with next-generation jet fuel technology, LanzaJet exemplifies the type of commercially viable, scalable SAF solution that can drive the aviation industry toward its 2050 net-zero commitments.
Upstream Innovation
While the ATJ pathway has historically been tied to carbohydrate- and sugar-based ethanol, LanzaJet is demonstrating that its platform extends far beyond conventional feedstocks. Through CirculAir™, a joint innovation with LanzaTech, LanzaJet is proving that ATJ can be powered by a broad spectrum of non-traditional carbon sources. CirculAir integrates LanzaTech’s carbon recycling expertise with LanzaJet’s commercially proven ATJ technology, enabling the transformation of waste streams such as agricultural residues, municipal solid waste, and industrial off-gases into ethanol, which can then be upgraded into drop-in SAF.
Beyond waste biomass, CirculAir also supports the production of Power to Liquids (PtL) or e‑fuels, converting captured CO₂ – whether from direct air capture (DAC) or industrial emissions – into SAF precursors. This flexibility allows the platform to aggregate, synthesize, and ferment diverse carbon-rich inputs into a renewable ethanol stream, ultimately broadening the scope of feedstocks that can contribute to global SAF supply.
LanzaJet’s ability to harness this feedstock diversity sets it apart from other SAF pathways that remain constrained by finite resources such as waste oils and fats. By leveraging the abundant global ethanol supply chain and extending it with novel carbon inputs, LanzaJet ensures both flexibility and scalability in its SAF production.
The company’s global footprint underscores its ambition. Beyond its flagship Freedom Pines Fuels facility in Georgia, LanzaJet is advancing major projects in the UK, France, Japan, Australia, and India. Each regional deployment leverages local feedstocks and policy frameworks, creating a decentralized yet globally connected production network.
With ATJ and the CirculAir integration, LanzaJet is future-proofing the industry’s fuel supply by unlocking new carbon sources, aligning with global sustainability mandates, and building a replicable global infrastructure. This positions the company as a transformative leader in aviation’s pathway to net zero.
Government Support Driving SAF Industry Growth
Government policies remain essential to scaling SAF globally. While the approach and pace may differ across regions, one constant is clear: long-term investment in SAF is increasingly seen as a strategic pathway toward cleaner skies and stronger energy systems.
The U.S. has made significant strides in recent years, including the introduction of SAF-specific incentives. While federal SAF policy is evolving under new leadership, support for domestic ethanol producers, rural job creation, and energy security continues to resonate across the political spectrum. In parallel, a number of states are advancing their own efforts to accelerate SAF deployment, adding valuable momentum to the broader U.S. landscape.
Europe is moving forward with long-term regulatory clarity. The ReFuelEU Aviation Regulation mandates SAF blending targets beginning at 2% in 2025 and ramping up to 70% by 2050. This provides a strong signal for investment and gives fuel producers a stable foundation to scale SAF infrastructure across the region.
The UK has committed to a 10% SAF mandate by 2030 and is actively supporting the development of domestic SAF production through capital grants and policy incentives. With strong airline engagement and a coordinated industry-government approach through initiatives like the Jet Zero Council, the UK is positioning itself as a leader in the next generation of clean aviation technologies.
Japan has set a national target for SAF to make up 10% of jet fuel consumption by 2030. Backed by the Ministry of Economy, Trade and Industry (METI), the country is investing in domestic SAF production and forming partnerships to accelerate deployment. With a focus on energy security and international collaboration, Japan is emerging as a key player in the regional SAF ecosystem.
Australia is stepping up its SAF ambitions through state and federal initiatives. Programs like the Jet Zero Council and funding support from the Australian Renewable Energy Agency (ARENA) are helping to advance SAF projects, with a focus on regional development, domestic fuel resilience, and decarbonization.
India is emerging alongside these international developments. In a notable step, state‑controlled refiner Indian Oil Corporation aims to achieve at least 1 percent SAF blending in jet fuel by the July – September quarter of 2025, ahead of the government’s official 2027 target for international flights. That SAF mandate is set to double to 2 percent by 2028, and plans are underway to build dedicated SAF production facilities to support India’s net‑zero ambition by 2070.
From established policies to new pathways under development, governments around the world are helping lay the foundation for a cleaner aviation future – and SAF is increasingly at the center of that transition.
The Future of Flight Depends on SAF
SAF isn’t just a niche solution. It’s the key to ensuring that aviation remains a viable and responsible mode of transportation. As air travel continues to grow, so does the urgency of reducing its environmental impact. SAF provides a real, scalable solution to cutting aviation’s lifecycle emissions while maintaining the connectivity and economic benefits that air travel enables. Unlike other aviation technologies that require entirely new infrastructure and aircraft designs, SAF can be used in today’s jets, making it the fastest and most effective way to decarbonize the industry.
But for SAF to reach its full potential, it needs investment, policy support, and public awareness. Scaling SAF requires building production facilities, expanding supply chain infrastructure, and ensuring that airlines have access to affordable, low-carbon fuel. Governments play a crucial role in setting policies and incentives that encourage SAF production, but so do businesses, investors, and everyday travelers.
If you’re an airline passenger, you can support SAF by choosing flights that use sustainable fuels and advocating for cleaner aviation. If you’re in business or government, you can push for policies that accelerate SAF adoption and invest in solutions that will secure the future of sustainable aviation. The transition to SAF is happening now, and with continued momentum, it will play a defining role in shaping the future of flight.