Researchers from the United Kingdom’s University of Bath have discovered a way to turn used coffee grounds into an alternative fuel to power vehicles. The process, called transesterification, chemically transforms the grounds into biodiesel.

The study, which was published in the ACS Journal Energy & Fuels, explains how the researchers extracted oil from coffee grounds by soaking them in an organic solvent and then chemically transformed them into biodiesel.

“This oil also has similar properties to current feedstocks used to make biofuels. But, while those are cultivated specifically to produce fuel, spent coffee grounds are waste. Using these, there’s a real potential to produce a truly sustainable second-generation biofuel,” said Dr Chris Chuck, from the University’s Department of Chemical Engineering.

In all, the researchers made biofuel from ground coffee produced in 20 different geographic regions, including caffeinated and decaffeinated forms, as well as Robusta and Arabica varieties. While the researchers understand that coffee biodiesel would be a relatively minor player in the alternative fuel industry, it could be produced on a small scale by coffee shop chains to fuel vehicles used for deliveries. These same delivery vehicles could be used to collect spent coffee grinds and take them to a central biodiesel production facility to be processed.