Biofuel from sugarcane to power planes

New York: A team of researchers that includes a number of Indian origin scientists has developed a process for producing drop-in aviation biofuel from sugarcane.

The discovery could revolutionise the aviation as well as sugar industry and can bring down the carbon emissions. Currently, aviation is the source of two percent of the annual greenhouse gas emissions from human activity.

While biofuels have proven to be an effective, renewable, low-carbon alternative to gasoline and diesel, jet fuels pose unique challenges.

"Jet fuels must be oxygen-free, have the right boiling point distribution and lubricity and a very low pour point, meaning the fuel can not become gelatinous in the cold temperatures of the stratosphere," said co-author Amit Gokhale.

These challenges have now been met with a new technique developed by researchers at the Energy Biosciences Institute (EBI).

"The recyclable catalysts we have developed are capable of converting sugarcane biomass into a new class of aviation fuel and lubricants with superior cold-flow properties, density and viscosity that could achieve net life-cycle greenhouse gas savings of up to 80 percent," said corresponding author Alexis Bell.

In a 2014 report, the Intergovernmental Panel on Climate Change (IPCC) in the US pointed out that drop-in biofuels are the only viable alternative to conventional jet fuels.

The process developed at EBI can be used to selectively upgrade alkyl methyl ketones derived from sugarcane biomass into trimer condensates with better than 95 percent yields.

These condensates are then hydro-deoxygenated into a new class of cycloalkane compounds that contain a cyclohexane ring and a quaternary carbon atom.

These cycloalkane compounds can be tailored for the production of either jet fuel or automotive lubricant base oils.

The ability of the EBI process to yield jet fuel or lubricants should be a significant advantage for biorefineries.

"Sugarcane biorefineries today produce ethanol, sugar and electricity. Expanding the product slate to include aviation fuels and lubricant base oils could allow for operators to manage their market risks better," Gokhale added.

Another important advantage offered by the new process is that it enables refineries to convert a portion of the bagasse - the fibrous residue that remains after juice is extracted from sugarcane stalk - into fuels and other products, the researchers said.

The rest of the waste biomass can be combusted to produce process heat and electricity to operate the refinery.

This new EBI process for making jet fuel and lubricants could also be used to make diesel and additives for gasoline, Gokhale said.

"With some minimal modifications to both the catalysts and the reaction schemes we can produce drop-in diesel as well."

The study appeared in the Proceedings of the National Academy of Sciences (PNAS).