Biojet fuel represents a significant advancement in the pursuit of sustainable aviation. It offers a pathway to reduce the environmental footprint of air travel by providing an alternative to conventional jet fuel. As the aviation industry seeks to address its carbon emissions, biojet fuel emerges as a practical solution, capable of powering existing aircraft infrastructure. This fuel supports efforts to decarbonize the global aviation sector.
What is Biojet Fuel?
Biojet fuel, also known as sustainable aviation fuel (SAF), is a type of jet fuel derived from biological resources rather than fossil fuels. It is chemically similar to traditional petroleum-based jet fuel, allowing it to be a “drop-in” replacement without requiring modifications to aircraft engines, fuel infrastructure, or distribution systems. This compatibility simplifies its integration into current aviation operations. Biojet fuel is designed to perform at parity with conventional jet fuel.
Biojet fuel is produced through various chemical conversion processes from renewable, biologically derived materials. This distinguishes it from conventional jet fuels, which are primarily refined from crude oil. The molecular structure of biojet fuel typically consists of a blend of hydrocarbons, ensuring its suitability for use in jet engines.
Environmental Advantages
The primary environmental benefit of biojet fuel lies in its ability to significantly reduce greenhouse gas (GHG) emissions compared to conventional jet fuel. Biojet fuel can lower lifecycle carbon dioxide (CO2) emissions by 50% to 80%, with some pathways potentially achieving up to a 98% reduction. This substantial decrease is attributed to the renewable nature of its source materials, where the carbon emitted during combustion is part of a more rapid, natural carbon cycle.
Beyond carbon reductions, biojet fuel also contributes to improved air quality. It generally contains lower sulfur content than traditional jet fuel, which leads to reduced sulfur oxide emissions and less particulate matter formation. The use of biojet fuel can also help mitigate the impact of aviation on climate change by decreasing reliance on fossil fuels and promoting sustainable practices.
Diverse Sources and Production Pathways
Biojet fuel can be produced from a wide array of biological feedstocks, which are broadly categorized into first, second, and third generations. These sources include used cooking oil, animal fats (tallows), agricultural waste (like corn stover or sugarcane bagasse), forestry residues, and dedicated energy crops such as camelina or jatropha. Algae also show promise as a feedstock.
Several certified production technologies convert these diverse feedstocks into biojet fuel that meets aviation standards, such as ASTM D7566. One prominent pathway is Hydroprocessed Esters and Fatty Acids (HEFA), which converts oils and fats through a hydrotreatment process. Another established method is Alcohol-to-Jet (ATJ), which processes alcohols into synthetic paraffinic kerosene. Other emerging pathways include Fischer-Tropsch (FT) synthesis, which converts solid biomass or waste gases into synthetic paraffinic kerosene, and Catalytic Hydrothermolysis (CHJ) from vegetable and algae oils.
Real-World Use and Future Trajectory
Biojet fuel is increasingly being adopted in commercial aviation, typically blended with conventional jet fuel. ASTM International standards, such as D7566, allow for blends of biojet fuel up to 50% with traditional jet fuel, ensuring safety and performance. Airlines are increasingly procuring sustainable aviation fuel, with major suppliers like Neste and World Energy emerging.
The adoption of biojet fuel is also supported by regulatory frameworks. The European Union’s ReFuelEU Aviation proposal mandates a 2% SAF blend from 2025, increasing to 70% by 2050. Despite current production representing a small fraction of global jet fuel use (around 0.2-0.3% in 2023-2024), projections indicate a substantial increase, with forecasts ranging from 2 billion to 8 billion liters by 2030. While challenges such as higher production costs and feedstock availability persist, ongoing technological advancements and policy support aim to expand biojet fuel’s role in aviation decarbonization, with continued research into diverse feedstocks and more cost-effective conversion processes.