The Growing Role of Biofuels in Aviation

The global aviation sector is under increasing pressure to decarbonize. Air travel accounts for roughly 2.5% of global CO₂ emissions, and with passenger demand projected to double by 2050, the need for sustainable alternatives to fossil-based kerosene is urgent. Biofuels — specifically sustainable aviation fuels (SAF) produced from biomass — have emerged as one of the most viable near-term solutions. Unlike electric or hydrogen propulsion systems, biofuels are drop-in compatible with existing aircraft engines and fueling infrastructure. This makes them a practical option for reducing lifecycle greenhouse gas emissions without requiring a complete overhaul of the current fleet.

Yet the path to widespread adoption is not straightforward. While biofuels offer notable environmental and strategic advantages, they also present significant economic, technical, and logistical hurdles. Understanding both sides is critical for stakeholders — from policymakers and airlines to fuel producers and passengers — as the industry moves toward its goal of net-zero carbon emissions by 2050.

Benefits of Biofuels in Aviation Propulsion Systems

Significant Reduction in Lifecycle Carbon Emissions

The primary argument for biofuels is their potential to lower CO₂ emissions. Unlike fossil fuels, which release carbon that has been locked underground for millions of years, biofuels are derived from recently living organic matter — such as oilseeds, agricultural residues, or municipal waste. The carbon released during combustion is roughly equivalent to the carbon absorbed by the feedstocks during growth. Depending on the feedstock and production pathway, SAF can reduce lifecycle greenhouse gas emissions by 50% to 80% compared to conventional jet fuel, according to the International Civil Aviation Organization (ICAO).

This carbon cycle advantage is particularly meaningful when using waste-based feedstocks (e.g., used cooking oil, forestry residues) because they avoid the land-use change emissions associated with dedicated energy crops. Moreover, certain production processes — such as the hydroprocessed esters and fatty acids (HEFA) route — have reached commercial maturity and are already supplying blended SAF to major airports.

Enhanced Energy Security and Feedstock Diversity

Biofuels reduce reliance on geopolitically unstable oil-exporting regions. Since feedstocks can be sourced locally from agricultural, forestry, or municipal waste streams, nations can diversify their fuel supply and buffer against price volatility. The International Air Transport Association (IATA) notes that a robust SAF industry could create new economic opportunities in rural and industrial sectors, from farming to waste management.

Additionally, the wide variety of potential feedstocks — including camelina, jatropha, algae, and even industrial off-gases — means that no single supply chain bottleneck can cripple production. This flexibility makes biofuels a resilient option for a rapidly changing global energy landscape.

Drop-in Compatibility with Existing Infrastructure

One of the most compelling advantages of biofuels is their drop-in nature. Blends of up to 50% SAF (by volume) with conventional Jet A/A-1 are certified for use in current aircraft engines without modifications. This means airlines can immediately start reducing emissions without waiting for new airframe or engine designs. Major airlines, including United, KLM, and Qantas, have already operated commercial flights using SAF blends. The only requirement is proper blending at the fuel terminal — no changes to aircraft hardware, fueling trucks, or storage tanks are needed.

This compatibility extends to the propulsion system itself. Biofuels have similar energy density, freezing point, and combustion characteristics to conventional kerosene, ensuring safe and reliable engine performance. Extensive testing by engine manufacturers such as Rolls-Royce, GE Aviation, and Pratt & Whitney has confirmed that approved SAF blends meet or exceed all relevant specifications (e.g., ASTM D7566).

Challenges of Using Biofuels in Aviation

High Production Costs and Limited Scalability

Despite technological progress, the cost of SAF remains two to four times higher than that of conventional jet fuel. This price premium is the single greatest barrier to widespread adoption. The production processes require significant capital investment, and many pathways (such as alcohol-to-jet or Fischer-Tropsch) are still at early commercial or pilot scale. As a result, SAF accounts for less than 0.1% of global jet fuel consumption.

Scaling up production to meet even 10% of global demand by 2030 would require dozens of large-scale biorefineries and a reliable, sustainable supply of feedstocks. The International Energy Agency (IEA) highlights that policy support — in the form of blending mandates, carbon pricing, and production tax credits — is essential to bridge the cost gap and incentivize investment. Without such measures, the economic viability of biofuels in aviation will remain marginal.

Sustainability Concerns: Feedstock Competition and Land Use

Not all biofuels are created equal. If feedstocks are grown on land that could otherwise produce food, or if forests are cleared to make room for energy crops, the environmental benefits can be partially or wholly negated. This indirect land-use change (ILUC) risk is a major concern for first-generation biofuels derived from food crops like corn, soy, or palm oil. Responsible certification schemes, such as the Roundtable on Sustainable Biomaterials (RSB), require producers to demonstrate that feedstocks do not compete with food or cause deforestation.

Advanced biofuels — from waste oils, agricultural residues, or dedicated non-food crops grown on marginal land — avoid most of these pitfalls. However, these feedstocks are often geographically dispersed, have lower energy density per hectare, and require more complex logistics. Ensuring that biofuel production remains truly sustainable demands rigorous lifecycle analysis and strong governance.

Technical Barriers in Engine Integration and Performance

Although most approved SAF blends work seamlessly in current engines, certain technical challenges persist at higher blend ratios. For example, biofuels generally have lower aromatic content than conventional jet fuel. Aromatics are essential for swelling fuel system seals and ensuring proper lubrication. At blend ratios above 50%, some engines may experience seal shrinkage or reduced lubricity, requiring modifications or special additives.

Another technical hurdle is the impact on aircraft range and payload. While the energy density of SAF is similar to Jet A-1, it is still lower than the theoretical maximum. For ultra-long-haul flights, where weight and fuel volume are critical, airlines may need to accept slightly reduced payloads or additional fuel stops. Testing is ongoing to certify 100% SAF blends for all engine types — an important milestone for achieving maximum carbon reduction.

Cold flow properties also require attention. Certain biofuels, especially those derived from animal fats or some vegetable oils, can have higher freezing points than conventional kerosene. Additives or blending with other fuel components may be needed to prevent wax formation at cruising altitudes of −50°C and below.

Regulatory and Certification Hurdles

Aviation fuel is one of the most tightly regulated commodities in the world. Every new fuel pathway must undergo extensive testing and certification before it can be used in commercial aircraft. The ASTM D4054 evaluation process can take years and cost millions of dollars. While this ensures safety, it slows down innovation and makes it difficult for novel production routes (e.g., power-to-liquids, algae-based) to reach the market quickly.

In addition to certification, a complex web of carbon accounting standards, sustainability criteria, and blending mandates varies across jurisdictions. The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) allows airlines to count SAF towards their emissions reduction targets, but only if the fuel meets specific lifecycle thresholds. Harmonizing these rules globally would reduce administrative burden and increase investor confidence.

Pathways Forward: Economic Viability, Innovation, and Policy

Cost Reduction through Technology and Scale

The road to cost parity runs through scale, learning curves, and technological breakthroughs. As more SAF production plants come online, capital and operating costs will fall — similar to what happened with solar and wind energy. Research into advanced feedstocks, such as genetically modified algae or gasified municipal solid waste, could drastically lower feedstock costs and improve yields.

Drop-in fuels from the power-to-liquids (PtL) process — which uses renewable electricity to split water and combine the hydrogen with captured CO₂ — offer virtually unlimited feedstock potential and very high lifecycle carbon savings. Although currently one of the most expensive pathways, PtL could eventually become competitive as renewable electricity prices decline. Governments and private consortia are already funding demonstration plants in Europe, the US, and Asia.

The Role of Policy and Market Instruments

Blending mandates are the most effective tool for driving SAF adoption. The European Union's ReFuelEU Aviation regulation requires fuel suppliers to blend increasing percentages of SAF from 2025 onward, rising to 70% by 2050. Similar mandates are under consideration in the UK, Japan, and the US (via the Sustainable Aviation Fuel Grand Challenge). These regulatory signals give producers the long-term certainty needed to invest in large-scale facilities.

Carbon pricing mechanisms, such as emissions trading systems (e.g., EU ETS) or CORSIA offset credits, further improve the relative economics of SAF by putting a price on the carbon emissions of conventional fuel. Book-and-claim systems, where the environmental attributes of SAF can be sold separately from the physical fuel, also help airlines access the benefits of SAF even if it is not available at their home airport.

Comparison with Other Sustainable Aviation Technologies

Biofuels are not the only game in town. Hydrogen and battery-electric propulsion are being actively developed for short-range aircraft, but both face fundamental barriers for long-haul operations. Hydrogen has a lower volumetric energy density than kerosene and requires entirely new aircraft designs, cryogenic storage, and airport infrastructure. Battery-electric systems remain far too heavy for commercial passenger jets, and are unlikely to power anything larger than regional turboprops before 2050.

By contrast, biofuels (and synthetic PtL fuels) can be used in existing aircraft and infrastructure, offering immediate emission reductions. They are a bridge technology that can start decarbonizing aviation today while other technologies mature. Even after hydrogen and electric aircraft become viable, SAF will likely still be needed for long-haul flights, where the energy density requirements are highest.

Conclusion

Biofuels offer a credible, actionable path to reducing aviation's carbon footprint without sacrificing the safety, range, or convenience that passengers and cargo operators rely on. Their benefits — lifecycle emissions savings, energy diversity, and drop-in compatibility — are well documented and increasingly backed by real-world operations. However, the challenges of high cost, sustainable feedstock supply, technical integration at high blend ratios, and regulatory fragmentation remain formidable.

Overcoming these barriers will require a concerted effort from industry, governments, and researchers. Accelerating certification processes, scaling up production capacity, and aligning sustainability standards across markets are essential steps. With appropriate policy support and continued innovation, biofuels can play a central role in the aviation industry's transition to net-zero emissions, helping to keep global connectivity sustainable for future generations.