Can sustainable biofuels fully replace aviation jet fuel?

How much can sustainable biofuels actually reduce aviation emissions?

Sustainable aviation fuels (SAF) can deliver substantial greenhouse gas (GHG) reductions, but the exact amount depends heavily on the feedstock and production process. A comprehensive life-cycle assessment found that SAF made from waste or residues can cut GHG emissions by up to 35% compared to conventional JET A-1 fuel [3]. That means for every gallon of jet fuel replaced, you avoid about a third of the carbon pollution.

Even deeper cuts are possible with advanced production methods. One study of a net-zero biofuel plant design showed that combining renewable energy, renewable hydrogen, and carbon capture and storage (CCS) can reduce the carbon intensity of SAF to -3.5 grams of CO₂ equivalent per megajoule — meaning the fuel actually has net-negative emissions [5]. In plain terms, producing and burning that fuel removes more carbon from the atmosphere than it adds. The same plant could cut 514,000 metric tons of GHG per year compared to petroleum jet fuel [5].

A broader review of biofuel technologies confirms that jet biofuels could potentially reduce GHG emissions by up to 80% relative to fossil fuels [2]. However, these high reductions require optimized catalysts and feedstocks, and are not yet achieved at commercial scale.

Why can't we just use 100% biofuel in jet engines?

The main technical hurdle is that high blending ratios of biofuel can degrade engine performance, especially during atomization — the process of breaking fuel into fine droplets for efficient combustion. A 2025 simulation study found that when the biofuel blend exceeded 50%, the liquid film in the nozzle became thicker, which reduces atomization efficiency and can lead to incomplete combustion and more soot [1]. At low injection pressure (0.2 MPa), the difference in film thickness between low- and high-blend fuels was significant, hurting performance.

However, the same study showed that this problem largely disappears at higher operating pressures. At 1.0 MPa (typical of modern jet engines at cruise), the difference in liquid film thickness between a 40% blend and 100% biofuel shrank to just 4.2% [1]. This means that with proper engine tuning and higher pressures, very high blends — even 100% biofuel — could work. Fuel temperature also matters: warming the fuel from 0°C to 50°C reduced film thickness by 52.8% for high-blend fuels, making atomization much better [1]. So the barrier is not insurmountable, but it requires engineering adjustments.

Is there enough sustainable biomass to replace all jet fuel?

Feedstock availability is a major constraint. The aviation industry consumes 1.5–1.7 billion barrels of jet fuel per year, which is an enormous volume [2]. One promising source is lignin, a plant polymer that is currently burned for energy. A 2024 review estimated that lignin could meet the current demand for sustainable aviation fuel blendstocks 2.5 times over if fully utilized [4]. Lignin is abundant and has a higher energy density than other plant materials, making it an ideal candidate for producing the cyclic compounds needed in jet fuel [4].

But turning lignin into usable fuel requires advanced deoxygenation catalysts and depolymerization technologies that are still under development [4]. Other feedstocks like corn, oilseeds, and waste fats face competition with food production and have limited supply. The net-zero plant design mentioned earlier produces 170 million liters of SAF per year from corn — a significant amount, but only a tiny fraction of global demand [5]. So while the technical potential exists, scaling up production to fully replace fossil jet fuel would require massive land use, infrastructure investment, and technological breakthroughs.

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