While the Brits might be known for their tea, it could be coffee that fills their biodiesel tanks. Researchers at the University of Bath have found a way to turn coffee grounds into biodiesel.
Oil can be extracted from coffee grounds by soaking them in an organic solvent, before being chemically transformed into biodiesel via a process called “transesterification”. The study, recently published in the ACS Journal Energy & Fuels, looked at how the fuel properties varied depending on the type of coffee used.
As part of the study, 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.
Dr Chris Chuck, Whorrod Research Fellow from our Department of Chemical Engineering, explained: “Around 8 million tonnes of coffee are produced globally each year and ground waste coffee contains up to 20 per cent oil per unit weight.
“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.”
The researchers found a surprisingly high level of consistency among the various types of coffee grounds for their appropriateness as a biodiesel feedstock.
The work seems to be in line with other studies we have reported on here on Domestic Fuel, including a London startup looking to turn coffee grounds into biodiesel and work at the University of Cincinnati.