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Why Sustainable Aviation Fuel Isn’t Winning Against Cheap Fossil Jet Fuel

As air travel seeks greener skies, expensive production and cheap fossil fuels slow sustainable aviation fuel's breakout.

By Medha deb

Created on Sep 26, 2025

As air travel seeks greener skies, expensive production and cheap fossil fuels slow sustainable aviation fuel's breakout.

Sustainable aviation fuel (SAF) has long been hailed as a vital step toward reducing the carbon footprint of passenger and freight aviation. Airline executives, policymakers, and environmental advocates see SAF as a practical way to decarbonize a sector known for high emissions and slow progress on climate targets. Yet, despite bold promises and significant investments, SAF production and adoption remain limited, hindered by persistent economic and political barriers—and overshadowed by the relentless affordability of fossil-derived jet fuels.

What Is Sustainable Aviation Fuel?

SAF refers to non-fossil-derived jet fuel replacements made from renewable resources, such as waste oils, agricultural residues, municipal solid waste, or even algae. Unlike conventional jet fuels refined from petroleum, SAFs can, when made from truly sustainable feedstocks, slash lifecycle greenhouse gas emissions by up to 80% compared to fossil jet fuel.

Feedstocks: Cooking oil, animal fats, crop residues, waste wood, municipal solid waste, algae, and dedicated non-food energy crops.
Blending: SAF is typically “drop-in”—it can be blended with traditional jet fuel (up to 50% in most jurisdictions) without changing engines or infrastructure.
Certifications: Global organizations, including ASTM International, provide specifications ensuring quality and safety for SAF blends.

Why Airlines Want to Use SAF

Commercial aviation is under growing scrutiny for its carbon emissions. Governments and regulators are tightening emissions targets, with leading bodies like the International Air Transport Association (IATA) and many national regulators committed to “net zero” aviation by 2050. For the industry to meet these commitments, wide adoption of SAF is viewed as one of the only viable near- to medium-term options.

While full-electric or hydrogen-powered flight is a long-term goal, existing aircraft and infrastructure can already use SAF, making it attractive for near-term decarbonization. Airlines promote their use of SAF as proof of their climate commitments, often marketing SAF-powered flights to eco-conscious travelers.

Emissions Cuts: SAF can provide up to 80% lifecycle CO₂ reduction compared to fossil jet fuel, depending on the feedstock and production process.
Existing Fleet Compatibility: “Drop-in” fuels don’t require new airplanes or airport equipment.
Public Image: Early adoption boosts airlines’ sustainability branding and appeals to consumers and investors.

The Scale of the Challenge

Despite the promise, SAF currently supplies less than 1% of global jet fuel demand. Ambitious projections show that to reach net zero by 2050, the industry will need some 449 billion liters of SAF annually—a staggering scale-up from today’s output. This would require enormous new investments in feedstock infrastructure, processing facilities, supply chains, and market incentives.

Key hurdles include:

Production Cost: SAF is typically two to five times more expensive than fossil jet fuel, even with economies of scale and subsidies considered.
Feedstock Availability: Competition with food security, land use constraints, and environmental risks limit which feedstocks can be considered “sustainable.”
Scaling Up: Existing biorefineries are small compared to petroleum refineries, and expansion is capital-intensive.

Why Is SAF So Expensive?

The primary reason SAF isn’t taking off faster is its high cost versus fossil jet fuel. Several factors drive these costs:

Feedstock Price and Scarcity: Many preferred feedstocks, like used cooking oil or waste animal fats, are limited in supply. As SAF demand increases, these prices rise further.
Complex Processing: SAF production involves more complex chemical and biological processes than refining crude oil, requiring high-energy inputs and advanced technology.
Regulatory Compliance: Strict sustainability certification and quality testing add costs at each step.
Underdeveloped Supply Chains: Fragmented collection, transport, and conversion infrastructure for biomass raise overheads—costs that large-scale fossil fuel supply chains have long optimized away.
Market Scale: Fossil fuel refineries benefit from massive economies of scale; SAF production remains boutique by comparison.

Fossil jet fuels, for their part, are cheaper due to established infrastructure, market stability, and untaxed or subsidized extraction. Unless oil prices rise sharply or policy changes—like taxing jet fuel or mandating SAF blending—bridge the cost gap, airlines gravitate toward cheaper options.

Factor	Sustainable Aviation Fuel	Fossil Jet Fuel
Feedstock Cost	High, limited supply	Low, abundant crude
Production Technology	Complex, evolving	Mature, optimized
Supply Chain	Fragmented, small scale	Integrated, global scale
Price Volatility	High, due to input scarcity	Moderate, but stable
Life Cycle Carbon Emissions	Up to 80% lower*	Baseline (high)
Policy Support	Growing, but inconsistent	Longstanding subsidies or no tax

*Depends on feedstock and process; poorly chosen bio-based SAFs can have higher life cycle emissions than petroleum.

Unpacking the Emissions Debate

While SAFs offer the potential to dramatically curb aviation’s carbon footprint, not all so-called “sustainable” fuels deliver on this promise. The climate benefits of SAF depend heavily on the source of feedstocks, how they’re grown or collected, and how production impacts land use or food security.

Main Concerns:

Land Use Change: Biofuels from crops like corn or soy often require clearing land or displacing food crops, leading to indirect emissions that cancel out climate gains.
Feedstock Sourcing: Waste and residue-based SAFs (e.g., used oils, ag residues) have lower impacts but are limited in volume.
Certification Complexity: Proper lifecycle analysis is essential, but modeling is fraught with uncertainty and subject to regulatory influence.
Regulatory Roadblocks: Recent U.S. government guidance expanded tax credits for SAFs made from some crop-based feedstocks, which critics argue could increase net emissions by incentivizing land conversion and food price hikes.

Environmental groups stress that only truly waste-based or well-managed residue sources—never food crops or indirect land-use drivers—should qualify for “sustainable” status and policy incentives.

Rival Green Technologies: Electric and Hydrogen Flight

SAF isn’t the only tool in the airline industry’s decarbonization kit—but alternatives face steeper barriers:

Hydrogen-Powered Aircraft: Promising for the long term, but require radical new aircraft designs and a massive hydrogen production and distribution network. Major airframes may not debut before 2035.
Full-Electric Aircraft: Great for short-haul flights with small payloads, but limited by battery weight and energy density. Commercially feasible only for niche markets in the coming decade.

Until these technologies mature, SAF is viewed as the critical bridge to lower emissions with the existing fleet and infrastructure.

Current Investments and Notable Initiatives

Global investment in SAF is ramping up. Governments, major oil and chemical companies, and research consortia are channeling funds to scale up feedstock production and build SAF-specific biorefineries.

Royal Dutch Shell: Constructing an 820,000-ton-per-year biofuels plant in the Netherlands—the largest in Europe for renewable diesel and aviation fuel from waste products.
LanzaJet Freedom Pines: U.S. facility with $50M investment from Microsoft, set to produce 10M gallons of SAF and renewable diesel each year, starting 2023, drawing from sustainable ethanol and waste.
Omega Green Project: Underway in Paraguay, this will provide substantial SAF batches from plant-based sources with the goal of regional supply.
Mexico’s SAF Cluster: National and multinational actors join to develop a reliable, economically viable chain from feedstock supply to airline uptake, building localized value streams.

Yet despite marquee projects, global SAF volume remains minute compared to fossil jet fuel—further highlighting the cost and supply gap.

Policy, Incentives, and the Future Trajectory

Bridging the cost gap will hinge on well-designed policies, rigorous sustainability criteria, and direct public funding or mandates. Among the emerging approaches:

Mandated Blending Quotas: Governments may require a minimum SAF percentage in all jet fuel sold—rapidly enlarging the market for producers.
Direct Subsidies and Tax Credits: The U.S. Inflation Reduction Act, for example, offers tax incentives for SAF adoption—though some experts warn these must be tightly linked to environmental performance.
Carbon Pricing: Raising or introducing a carbon tax on aviation fuels would make SAF relatively cheaper.
International Standards: Robust, transparent certification for what counts as truly sustainable SAF is critical to avoid unintended climate harms.

A key concern is that poorly targeted subsidies could encourage large-scale crop-based biofuels, risking greater emissions and global food insecurity. Policies that prioritize waste and residue-based inputs, and invest in next-gen feedstocks, offer the best route to meaningful emission reductions.

Frequently Asked Questions (FAQs)

Q: If SAF reduces emissions, why not switch immediately?

A: SAF remains two to five times more expensive than fossil jet fuel and is not yet available at the required scale. Widespread adoption demands substantial investment, supply chain buildup, and supportive policy intervention.

Q: What is the difference between biofuel and sustainable aviation fuel?

A: All SAFs are a subset of biofuels, but not all biofuels are sustainable. SAF stresses the use of waste or non-food crops, minimizing land use change and delivering net emissions cuts via strict lifecycle analysis.

Q: Can the aviation sector ever be fossil-free?

A: In the long run, yes—through a mix of SAF, hydrogen, electric aircraft, demand reduction, and carbon offsets. Over the next few decades, SAF will play the most prominent role, until hydrogen and electric options mature.

Q: Is there enough feedstock to supply large-scale SAF demand?

A: Not with current methods. Waste-based feedstocks are limited, and expansion risks land competition and food price inflation if not managed carefully. Breakthroughs in new, scalable inputs—like algae or industrial residues—are needed for SAF to truly scale sustainably.

Q: Will government mandates make SAF cheaper?

A: Mandates can drive up demand and production, gradually lowering costs via scale and technological advances. However, without adequate sustainability safeguards, mandates could incentivize less sustainable practices.

Conclusion: Charting a Viable Flight Path for Green Aviation

Sustainable aviation fuel offers the most immediate option for cleaning up the skies, but comes with a stiff economic price tag and thorny sustainability tradeoffs. Breaking SAF’s reliance on premium feedstocks, closing the cost gap, and ensuring robust environmental safeguards are essential for making cleaner flying a reality.

Ultimately, cheap fossil jet fuels and the aviation industry’s appetite for low costs remain significant headwinds to progress. Closing the price gap—through a mix of technological, regulatory, and economic shifts—will decide whether SAF helps aviation truly soar into a greener future.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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