Air travel may one day get a little greener thanks to an unlikely fuel source: coconuts.
Researchers at Osaka Metropolitan University have developed a biofuel made from coconut oil that can be blended with conventional jet fuel and used in existing turbine engines without significantly reducing engine efficiency.
The fuel may also help lower some harmful emissions from aircraft.
The idea behind coconut-based aviation fuel comes from the chemical structure of coconut oil. Its fatty acids have chain lengths similar to the hydrocarbon molecules found in jet fuel.
This means coconut oil could potentially be converted into aviation fuel without the complicated processing required for some other biofuels.
The researchers used a relatively simple production technique known as the cosolvent method. Coconut oil extracts are mixed with acetone and alcohol, allowing the biofuel to be produced at normal room temperature and pressure.
Because the process does not require extreme heat or pressure, it could reduce the amount of energy needed to manufacture the fuel.
The team produced two types of coconut biofuel. One, called FAME, was made using methanol, while the other, called FAEE, used ethanol. They then mixed different amounts of these fuels with Jet A-1, one of the most commonly used aviation fuels.
To see how well the mixtures performed, the researchers tested them in a small turbojet engine. They measured fuel consumption, engine efficiency and exhaust emissions.
As more coconut biofuel was added, the engine consumed somewhat more fuel. The researchers believe this happened because the coconut-based fuels contain less energy than conventional jet fuel. However, the engine’s overall thermal efficiency remained similar to that achieved with regular Jet A-1.
There was another encouraging result: hydrocarbon emissions decreased as coconut biofuel was added. Meanwhile, the researchers found no significant increase in carbon dioxide or nitrogen monoxide emissions.
Importantly, the experiments suggest that coconut-blended fuel could work in existing gas turbine engines without requiring major modifications or causing a substantial loss of performance.
Coconut biofuel could be particularly useful in Southeast Asia, where coconuts are widely grown.
According to the researchers, around 30% of harvested coconuts in the region are rejected because they do not meet commercial standards. Instead of being discarded, some of these coconuts could potentially become a local source of aviation fuel.
There is still plenty of work to do before airplanes can routinely fly on coconut-based fuel. The researchers want to improve fuel consumption and eventually develop technology that allows engines to operate on 100% biofuel.
They also plan to study long-term storage, compatibility with engine materials and the fuel’s total environmental impact.
If those challenges can be overcome, unwanted coconuts could someday help power aircraft while making aviation a little cleaner.
