Air travel is an important part of modern life, but it also contributes significantly to climate change.
The aviation industry produces a large amount of greenhouse gas emissions, and finding cleaner fuels for airplanes has become a major global challenge.
Now, researchers at the University of Illinois Urbana-Champaign have developed a new method that can turn food waste into sustainable aviation fuel (SAF).
The approach could help reduce waste while also lowering the environmental impact of flying.
Sustainable aviation fuel is made from renewable materials rather than fossil fuels. It can potentially reduce the amount of carbon released into the atmosphere.
However, producing enough SAF to meet the needs of the aviation industry remains difficult.
The researchers used food waste as their starting material.
Instead of sending leftover food to landfills, they converted it into a type of crude oil using a process called hydrothermal liquefaction, or HTL. This process uses heat and pressure to mimic the natural formation of crude oil, but it does so in a much shorter time.
After producing the crude oil, the team refined it into jet fuel.
Their new method differs from earlier approaches because it relies less on expensive chemical catalysts and makes greater use of distillation, a common industrial process used to separate different substances.
According to the researchers, this simpler process is both cheaper and more environmentally friendly.
The fuel produced by this method does not yet match the quality of standard jet fuel on its own. Instead, it needs to be mixed with conventional jet fuel before it can be used.
The researchers say this is not necessarily a problem. They compare it to ethanol, which is commonly blended with gasoline for cars. Their experiments focused on a mixture containing 50% sustainable aviation fuel and 50% conventional jet fuel. If a 50-50 blend works, lower blends of 10% or 20% should also be possible.
The team tested several important properties of the fuel to make sure it could meet aviation standards set by U.S. regulators. So far, the work has been done on a small scale. The researchers can now produce several liters of fuel in their laboratory, enough for diesel engine tests. The next major step will be testing the fuel in jet engines.
One of the biggest challenges is collecting the food waste itself. Most food waste ends up in landfills or wastewater treatment facilities. Gathering and transporting these materials for fuel production can be difficult and costly.
The HTL process also creates a liquid byproduct called HTL aqueous phase, or HTL-AP. This byproduct contains nutrients but can also be toxic. To deal with it, the researchers explored an electrochemical treatment method that can recover valuable acids and nutrients.
Although this treatment currently adds significant costs, the researchers believe future technological improvements could make it much more affordable.
Their analysis also suggests that the process could potentially achieve negative carbon emissions, meaning it could remove more greenhouse gases from the atmosphere than it produces.
The study demonstrates a promising way to transform urban food waste into cleaner jet fuel, creating a circular system where waste becomes a valuable resource while helping the aviation industry move toward a more sustainable future.
