The HEFA Feedstock Crunch Is Coming for SAF

Is alcohol-to-jet the easy answer?

Aviation is critical infrastructure for global connectivity and economic growth—but it is also one of the hardest sectors to decarbonize. Sustainable aviation fuel (SAF) has emerged as the leading solution. Driven by expanding regulation, particularly in the EU, SAF demand is rising fast, placing growing pressure on feedstock supply and accelerating the need for alternative conversion pathways. As the hydroprocessed esters and fatty acids (HEFA) pathway meets supply bottlenecks, alcohol-to-jet (ATJ) is increasingly looking like a viable, bankable addition.

Demand to Outpace HEFA Feedstock Availability

To date, HEFA remains the only commercialized SAF production pathway. It works by converting lipid-based feedstocks such as used cooking oil (UCO) into drop-in jet fuel, leveraging existing refinery assets across a wide range of feedstock suppliers. This model was already proven for renewable diesel and is now being scaled even further to accommodate a growing demand for SAF.

Even though novel feedstocks such as intermediate crops are being introduced to this pathway, the math speaks for itself: The HEFA pathway will reach a feedstock-supply crunch causing market players to look for alternatives. Among a wide range of innovative pathways to SAF, one of them stands out in particular as the natural choice after HEFA.

ATJ: The Most Cost-Effective Alternative to HEFA

ATJ benefits from an already established supply chain for ethanol production and distribution while providing the most cost-effective alternative to HEFA. Worldwide existing SAF producers have come to the same conclusion and are positioning themselves for ATJ to become the dominating pathway for the future of SAF.

While refiners seek to grow their SAF business, new players are also entering the market. In an era of geopolitical uncertainty, ethanol producers are actively looking to diversify—and SAF is predicted to be their most attractive growth opportunity. Built in record time and known for their entrepreneurial drive, ethanol producers have a strong track record of innovation, with U.S. producers in particular delivering consistent year-on-year productivity gains.

In recent years, reducing the carbon intensity (CI) has been another key focus area, and various initiatives are being explored. Improving farming practices while introducing carbon capture and storage are seen as key levers in increasing the value of ethanol and making it more attractive as a feedstock for SAF. All these initiatives are placing ATJ in the front row for future SAF production.

Image: Topsoe

ATJet™ Powered by Proven HydroFlex™, H2Bridge™ Solutions

ATJet™, a solution from Topsoe, was specifically designed to deliver competitive levelized cost of SAF from ethanol by maximizing SAF yield while minimizing capital expenditure (capex). The solution integrates three core components: ethanol-to-ethylene (ETE) conversion, oligomerization, and the established HydroFlex™ and H2Bridge™ technologies already in commercial use for SAF production.

The first step in the ATJ process is dehydration of ethanol into ethylene—a well-established technology in the chemicals industry, where bioethylene serves as a building block for polymer production. For ATJet™, this step is delivered in partnership between Topsoe and leading ETE technology providers, combining complementary competencies to offer a reliable and cost-effective integrated solution.

While bioethylene has value in polymer production, the ATJ pathway directs it toward SAF through selective oligomerization. Catalyst selectivity at this stage is critical for maximizing SAF yield. The oligomerization platform integrated into ATJet™ draws on extensive experience in refinery catalyst development.

A key design principle of ATJet™ is minimizing complexity and cost across the integrated solution. H2Bridge™ addresses one of the more significant cost drivers in SAF production by recycling coproducts to generate renewable hydrogen on-site, removing the need to import green hydrogen. This integration of hydrogen and fuels processing reflects a broad track record in commercializing such combined systems.

Many ATJ Projects in Countries Importing, Exporting Ethanol

ATJ projects are emerging globally, with activity concentrated in countries that either produce or import ethanol for SAF production. Ethanol output has grown significantly in markets like Brazil and India, historically driven by gasoline blending, and producers are increasingly looking to SAF as an alternative demand outlet to sustain industry growth.

Projects vary considerably in scale and setup. Many are fast-paced and innovative, often located adjacent to existing ethanol plants to capture operational synergies, with SAF capacities sized accordingly. Others, typically led by refiners, take a more centralized approach, importing ethanol from multiple sources into a single large facility. This model offers economies of scale but must balance investment and transportation costs as well as CI impact.

The ATJet™ process can be configured to suit both approaches. Key design variables—including feedstock origin, plant scale and site conditions—are optimized to achieve competitive levelized cost of SAF. Regulatory frameworks and incentive structures also differ significantly by region: Whether ethanol is used domestically in the U.S. or exported from Brazil to Japan, understanding the local business case is essential to arriving at the right process design for each project.

Higher Fuel Prices Increase Focus on Energy Diversity, Security

Jet-fuel prices have doubled amid the Middle East conflict and Strait of Hormuz disruptions, with European airports facing potential supply shortages. The crisis has thrown Europe’s dependence on imported fossil fuels into sharp relief. For many, it is a wake-up call—and an opportunity to accelerate investment in domestic SAF capacity, strengthening energy independence and security while advancing decarbonization. This is particularly pressing for defense, where aviation is central and supply-chain control is increasingly critical in a deglobalized world.

Agricultural residues could be a cornerstone of European SAF supply. Europe’s farmland holds significant potential for cellulosic ethanol production, with a growing number of technology suppliers and project developers working to unlock it. Crucially, agricultural residues are already ReFuelEU aviation-compliant and can be converted into ethanol and onward to SAF at a competitive cost.

The opportunity is clear—connecting European farmers to aviation customers and domestic defense needs through a truly local supply chain. As the push for energy independence intensifies, this is a chance Europe cannot afford to miss.

The Value of a Trusted, Experienced SAF Partner

Working with a technology and catalyst provider like Topsoe allows those exploring ATJ to harvest decades of experience in catalyst development, hydroprocessing and hydrogen technology. As both a licensor and catalyst provider, Topsoe works closely with refiners, ethanol producers and project developers across the full project lifecycle, from feasibility and process design through to commissioning and operations.

This breadth of experience across feedstocks, regions and project configurations means that regardless of project setup, the relevant expertise and technology are available to optimize the ATJ process for the lowest levelized cost of SAF. For those looking to evaluate or advance an ATJ project, Topsoe is positioned to provide the technical and commercial insight needed to move from concept to commercial production.

Author: Mathias Bøje Madsen

Business Development Manager

Topsoe

mabm@topsoe.com