Coffee biofuel to power the cars of the future

Coffee cup
18 Jun, 2014 7:00pm Joe Finnerty

Scientists find waste coffee can be made into biodiesel that could power our cars

Waste from Britain's ever-expanding glut of coffee shops could be used to fuel cars according to freshly-brewed research from scientists at the University of Bath.

Costa Coffee, Starbucks and Cafe Nero could be the next big petrol providers to rival BP and Shell if the process can be scaled up.

A coffee shop generates an average of 22lbs (10kg) of leftovers each day - enough to be converted into two litres of the biofuel. This would make it a relatively minor operation but coffee chains could use it to power their delivery vehicles.

These same delivery vehicles could be used to collect spent coffee grinds and take them to a central biodiesel production facility to be processed. Companies such as London-based bio-bean already produce biodiesel and biomass pellets from waste coffee grounds.

Rhodri Jenkins, a PhD student in Sustainable Chemical Technologies and first author of the study, said: “There is also a large amount of waste produced by the coffee bean roasting industry, with defective beans being thrown away. If scaled up, we think coffee biodiesel has great potential as a sustainable fuel source.”

The coffee fuel is produced by extracting oil from the coffee grounds and soaking them in an organic solvent. A special chemical process known as "transesterification" then converts them into biodiesel.

The fuel properties of the finished product vary depending on the type of coffee ground used but researchers found that all coffee grounds have a standard make up and relevant physical properties, irrespective of the source.

As part of the study, the researchers successfully made biofuel from ground coffee produced in 20 different parts of the world, including caffeinated and decaffeinated forms, as well as Robusta and Arabica varieties.

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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.”

Car's powered by Coffee? Whatever next? Tell us you thoughts in the comments section below...