The aviation industry faces an unprecedented challenge: achieving meaningful decarbonization while maintaining the global connectivity that modern commerce and society depend upon. As the sector grapples with contributing 2.5% of global CO2 emissions—with 80% originating from long-haul flights—the search for viable alternatives to conventional jet fuel has intensified.

Alternative Aviation Technology Challenges
The promise of electric and hydrogen-powered aircraft has captured headlines and imagination, yet both technologies face fundamental barriers that limit their near-term viability for commercial aviation. Electric aircraft confront the harsh reality of battery energy density constraints. Current lithium-ion technology achieves approximately 200 to 250 watt-hours per kilogram (Wh/kg), with expectations to plateau at around 300 Wh/kg due to fundamental chemistry limitations, compared to 12,000 Wh/kg for jet fuel. However, studies have identified that electric aviation would require 400 Wh/kg for general aviation applications and 750 Wh/kg for commercial regional air service, representing a two- to three-fold improvement that remains beyond current capabilities. While electric aircraft may serve a role on short-haul regional routes, their energy density limitations constrain their applicability to the majority of commercial aviation.

The infrastructure implications are equally daunting. Electric aviation would necessitate comprehensive airport charging systems, overhauls of electrical grid capacity, and aircraft redesign. To date, not a single commercial electric aircraft deployment has occurred in scheduled passenger service, underscoring the technological and economic hurdles that remain.

Hydrogen propulsion presents similar challenges. While hydrogen offers impressive energy density by weight, its storage requirements create significant design constraints. Liquid hydrogen must be maintained at -253 degrees Celsius, requiring specialized cryogenic storage systems that fundamentally alter aircraft architecture. The safety considerations, airport infrastructure modifications and lengthy recertification processes have proven so challenging that even Airbus recently scaled back its hydrogen aircraft program timeline.

These realities underscore that electric and hydrogen technologies will require significant technological breakthroughs before their full potential can be realized, highlighting the aviation industry’s need for immediate solutions to achieve its decarbonization goals.

SAF: The Drop-In Solution
Sustainable aviation fuel (SAF) offers a direct path to decarbonization by working within existing systems rather than requiring wholesale transformation. Produced from renewable feedstocks—including alcohols, used cooking oil, animal fats, municipal solid waste, agricultural residues and even captured CO2—SAF can blend with conventional jet fuel without modifying aircraft engines or airport infrastructure.

This compatibility is critical. Airlines operate on thin margins, and aircraft lifecycles span decades. A fuel that integrates with existing fleets enables immediate deployment without the massive capital investments required by alternative technologies.

The market has responded. Global SAF production is projected to reach 6.1 billion to 8.2 billion gallons annually by 2030, according to RMI’s Sustainable Aviation Fuel Market Outlook, up from about 350 million gallons in 2024—underscoring both industry commitment and scalability.

Today’s Leading Pathway
The dominant SAF production technology today is hydroprocessed esters and fatty acids (HEFA), which converts fats, oils and greases into jet fuel through hydrogen treatment. Its appeal lies in compatibility with existing refinery infrastructure, allowing producers to leverage current equipment with modifications.

However, HEFA faces constraints that limit long-term scalability; chief among them is feedstock availability. The U.S. produces about 23 million tons of suitable feedstock annually, with soybean oil accounting for 57% of supply. Used cooking oil is limited by collection logistics, while animal fats are geographically concentrated in states such as Nebraska, Texas and Iowa, increasing transportation costs and carbon intensity.

Competition from the renewable diesel market further complicates HEFA economics, as incentives often favor diesel production and intensify feedstock competition. Maximizing SAF yields also generates substantial naphtha byproducts—up to 25% of total output—which can become a low-value burden for facilities located far from petrochemical markets.

These factors create a complex optimization challenge. HEFA produces only paraffinic components, while conventional jet fuel requires 8% to 25% aromatics for proper engine performance. As a result, HEFA SAF must be blended with fossil jet fuel, limiting its carbon reduction potential. Producers must balance feedstock costs, blending requirements and infrastructure proximity while navigating agricultural commodity volatility.

Innovation in SAF Production
The industry’s response to HEFA’s challenges has been to diversify production pathways and optimize existing processes. Fischer-Tropsch technology, which converts solid waste after gasification into syngas into synthetic fuels, offers access to more abundant feedstocks but at higher capital and operating costs. Alcohol-to-jet pathways provide another alternative, though current processes remain energy-intensive and expensive.

Current ASTM standards limit most SAF pathways to 50% blending with conventional jet fuel. Still, the industry is moving toward higher blend ratios and eventually 100% drop-in synthetic fuels. Achieving this goal requires addressing the aromatic component gap in HEFA SAF production, making economical sources of these molecules crucial for future fuel specifications.

One particularly promising area involves upgrading the naphtha byproducts from HEFA and Fischer-Tropsch (FT) processes into aromatic components of SAF that are otherwise missing from these outputs. Rather than treating these naphtha materials as low-value byproducts, emerging add-on technologies can convert them into high-value aromatics. For example, Universal Fuel Technologies has developed a chemical processing technology that complements HEFA and FT by converting their naphtha byproducts into high-quality aromatic components essential for jet fuel.

The challenge of upgrading naphtha byproducts stems from two key factors: the chemical properties of paraffinic molecules, which make them difficult to convert into aromatics, and the small quantities produced at individual HEFA facilities, which preclude economies of scale. These chemical and economic dual constraints explain why few technologies have emerged to convert this low-value stream into higher-value products. However, this approach not only improves the economics of existing SAF production, but also addresses a critical technical requirement for future 100% SAF blends.

Economic Viability Through Integration
The future of SAF production likely depends on integrated approaches that maximize resource utilization and minimize waste. Rather than viewing each production pathway in isolation, the industry must consider how different technologies can complement each other.

The flexibility to adapt to changing market conditions becomes crucial as well. Feedstock availability and pricing fluctuate in response to agricultural cycles, regulatory changes, and competing demand. Production facilities that can adjust their operations—switching between different feedstocks or product slates based on market conditions—will have significant competitive advantages.

Scaling for Impact
Meeting aviation’s decarbonization goals requires SAF production to scale from hundreds of millions of gallons annually to tens of billions of gallons per year. This expansion demands not only technological improvements but also supply chain development, policy support and effective financing mechanisms. The industry must also develop production technologies that can compete economically with conventional jet fuel while maintaining the performance characteristics that aviation demands. This requires continued innovation in processing technologies, feedstock development and systems integration. In many cases, investors may be reluctant to fund HEFA and FT plants where the naphtha byproduct stream cannot be effectively monetized. Technologies that solve this byproduct utilization challenge become critical enablers, potentially transforming otherwise uneconomical projects into viable investments and accelerating the deployment of SAF production capacity.

An Immediate Path to Sustainable Aviation
While electric and hydrogen aircraft may eventually transform aviation, SAF offers the most viable path to immediate emissions reduction. Unlike alternative propulsion technologies that require fundamental changes to aircraft design and infrastructure, SAF works within existing systems while delivering measurable environmental benefits.

The industry’s commitment to sustainability is clear, yet progress depends on solutions that can be deployed at scale. SAF provides that bridge, linking today’s fossil fuel reliance with a fully sustainable aviation future. By advancing production technologies that address current economic and technical barriers, the industry can accelerate SAF adoption while moving toward the goal of 100% SAF.

Author: Alexei Beltyukov
CEO, Universal Fuel Technologies

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