Biojet FuelEdit
Biojet fuel, commonly referred to as sustainable aviation fuel (SAF), is a category of aviation fuels produced from renewable or waste-based feedstocks that can substitute conventional jet fuel in aircraft engines. SAF is designed as a drop-in fuel, meaning it can be blended with existing Jet fuelJet fuel without requiring changes to engines, fuel systems, or airport infrastructure. The appeal is that SAF can be integrated into current supply chains while delivering practical reductions in lifecycle greenhouse gas emissionslife-cycle assessment and helping with energy security by diversifying domestic feedstock sourcesCORSIA.
In recent years SAF has evolved from a research concept to a commercial option that multiple airlines, airports, and refineries are testing and deploying at scale. However, the debate surrounding SAF is serious and multifaceted. Supporters emphasize market-driven deployment, cost discipline, and real-world emissions benefits when feedstocks and pathways are carefully chosen. Critics point to the variability of environmental results across feedstocks, the cost burden relative to traditional jet fuel, and the risk that subsidies or mandates could distort markets or divert resources from other, potentially more effective climate actions. The conversation often centers on policy design, supply chain logistics, and the governance frameworks that certify sustainability and track emissions reductions across complex global supply chains.
Overview
Biojet fuel is produced through a range of technologies that convert renewable carbon sources into hydrocarbons compatible with standard aviation engines. Pathways include hydroprocessed esters and fatty acids (HEFA), Fischer–Tropsch synthesis from biomass, and Alcohol-to-Jet (ATJ) processes, among othersHEFA Fischer–Tropsch Alcohol-to-Jet. These fuels are intended to be compatible with existing aircraft and fueling infrastructure, allowing airlines to blend SAF with conventional Jet fuelJet fuel—a practice known as blending. Certification frameworks, notably ASTM D7566, set the technical rules for SAF to be used in commercial aviation, with some pathways approved for higher blend ratios as technology and production matureASTM D7566.
Feedstocks used for SAF span a broad spectrum. They include waste fats and oils, used cooking oilused cooking oil, municipal solid waste residues, forestry and agricultural residues, advanced non-edible oils, and, in some cases, specially cultivated energy crops. The diversity of feedstocks is a strength in theory, but it also raises questions about sustainability, land use, water consumption, and biodiversity. Sustainability certifications—such as the Roundtable on Sustainable Biomaterials (RSB) and the International Sustainability and Carbon Certification (ISCC)—play a key role in assuring buyers and regulators about feedstock provenance and process efficiencyRSB ISCC. Critics worry that some feedstocks could compete with food production or drive land-use change, while supporters contend that waste-based and residual feedstocks minimize these risks and create local economic benefitsIndirect land use change.
Feedstocks and Production
The SAF landscape recognizes multiple supply chains, each with different risk profiles and emission outcomes. Waste-derived feedstocks, including used cooking oil and animal fats, generally offer stronger greenhouse gas reduction profiles than crops grown specifically for fuel, assuming sustainable supply and proper accounting. Non-edible oil crops and agricultural residues provide additional options, though feedstock availability, price volatility, and seasonal supply cycles influence economics. Emerging pathways using gasification of biomass coupled with Fischer–Tropsch synthesis, or integrated biorefineries that upgrade various waste streams, aim to expand the mix of viable SAF sourcesFischer–Tropsch.
Sustainability accounting remains central. Lifecycle assessments quantify emissions from feedstock cultivation, processing, conversion, distribution, and end use. While some pathways demonstrate sizable net reductions in lifecycle greenhouse gas emissions, others can be closer to parity with conventional jet fuel, particularly when indirect land-use change (ILUC) and co-products are not fully accounted for. This has led to ongoing debates about the best methods for measuring and crediting emissions, and about the role of SAF in a broader climate strategylife-cycle assessment Indirect land use change.
Environmental and Economic Impacts
The environmental case for SAF rests on lifecycle greenhouse gas reductions relative to petroleum-based aviation fuel. Real-world outcomes depend heavily on feedstock choice, supply chain efficiency, and co-product credits. Waste-based feedstocks tend to deliver larger reductions, while some cultivated feedstocks raise concerns about land use, water use, or biodiversity impacts. The variability of outcomes is why independent verification, transparent reporting, and credible certifications matter.
Economically, SAF faces cost premia compared with conventional jet fuel, driven by feedstock prices, conversion technology maturity, and scale. Price differentials can be amplified by carbon pricing, regulatory incentives, and mandates. Proponents argue that the long-run economics improve as production scales up, feedstock markets stabilize, and data on emissions reductions solidify. Critics warn that policy design must avoid masking true costs or creating dependency on subsidies that could distort airline pricing or consumer costs. The economics of SAF intersect with broader energy policy, including how governments price carbon, structure fuel mandates, and support research and development in biorefininglife-cycle assessment carbon pricing.
Policy, Regulation, and Debates
The policy discussion around biojet fuel blends into broader climate and energy policy. In the United States, SAF promotion has involved a mix of tax incentives, fuel-blending mandates, and research subsidies, alongside adherence to environmental and sustainability standards. In Europe, SAF policy intersects with RED II and broader transport decarbonization goals, leveraging carbon markets and sustainability criteria to drive demandRED II. International coordination, through bodies such as the International Civil Aviation Organization (ICAO), seeks to align aviation emissions goals with market-based measures like CORSIA (Carbon Offsetting and Reduction Scheme for International Aviation)CORSIA.
A central debate concerns mandates versus market-based incentives. Proponents of mandates argue for predictable demand that drives investment in SAF production and infrastructure. Critics contend that mandates without robust sustainability safeguards or with poorly designed price signals can raise airline operating costs and potentially shift costs onto passengers or downstream industries. A key right-of-center concern is to align public support with demonstrable performance—emphasizing transparent metrics, scalable private-sector investment, and a regulatory framework that avoids unnecessary burdens while ensuring real emissions reductionsRoundtable on Sustainable Biomaterials (RSB).
Controversies also arise around “greenwashing” concerns—where claimed benefits may be overstated or rely on questionable accounting methods. From a pragmatic standpoint, policy responses focus on independent verification, credible life-cycle assessments, and avoiding policy designs that deter innovation or create bottlenecks in fuel supply. Supporters argue that SAF is a pragmatic, scalable bridge to lower emissions in the near term, while detractors may call for delaying deployment until alternatives are available; the former view emphasizes near-term risk reduction and energy security, while the latter stresses the need for comprehensive decarbonization across all sectors.
Some critics contend that SAF subsidies could distort the aviation market by subsidizing fuel in a way that masks underlying cost pressures and delays the adoption of more transformative technologies, such as electrified propulsion for short-haul flights or improvements in air traffic efficiency. Advocates respond that SAF complements other measures and can be deployed within a reasonable policy framework that prizes accountability and real emissions reductions, while also supporting domestic industries and jobs in rural and industrial sectorsRSB ISCC.
Industry Adoption and Market Trends
Airlines, airports, and fuel suppliers have increasingly integrated SAF into routine operations, with test flights, limited commercial flights, and gradually expanding blending programs. Market adoption is influenced by policy incentives, certification timelines, feedstock availability, and the ability to scale production to meet growing demand. Major industry players have invested in SAF production facilities or partnerships, signaling a move toward greater supply diversity and price discipline through competition. The development of supply chains and logistics—ranging from feedstock collection to processing facilities and distribution—has become a core part of expanding SAF access to fleets worldwideSustainable aviation fuel feedstock.
Global Landscape
SAF deployment varies by region, reflecting differences in fuel mandates, carbon pricing, feedstock access, and regulatory rigor. International frameworks, such as CORSIA, aim to stabilize demand and credit emissions reductions from international flights, while national and regional policies shape the incentives and constraints within which SAF markets operate. The aviation sector’s progress toward substantial SAF use depends on continued public-private collaboration, investment in scalable conversion technologies, and credible sustainability verification across bordersICAO.
Safety, Certification, and Infrastructure
Biojet fuels must meet rigorous safety and performance standards to ensure compatibility with existing engines and fuel systems. Certification processes, fuel handling guidelines, and compatibility testing are essential as SAF pathways mature. The industry emphasizes that SAF, when properly certified and produced under credible sustainability standards, can be used safely at scale and without requiring changes to aircraft design or flight operations. Infrastructure considerations include storage, blending facilities, and logistics networks that can accommodate SAF alongside conventional jet fuelJet fuel.