WASTE coffee grounds could be a "sustainable fuel source" for powering vehicles, according to researchers at the University of Bath.
The study found different varieties of coffee, both caffeinated and decaffeinated, found all over the world had the relevant physical properties to make fuel.
This means all coffee waste could be a "viable" way of producing biodiesel, said scientists from the University's Centre for Sustainable Chemical Technologies.
Waste produced from the average coffee shop - around 22lb a day - was enough to produce about two litres of biofuel.
Research fellow Chris Chuck said: "Around eight 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 has similar properties to current feedstocks used to make biofuels. But, while those are cultivated specifically to produce fuel, spent coffee grounds are waste. With these, there's a real potential to produce a truly sustainable second-generation biofuel."
Oil can be extracted from coffee grounds by soaking them in an organic solvent before a process called transesterification transforms them into biodiesel, he said.
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