Coffee Could Fuel You, and Your Car

Jan. 20, 2008 -- Coffee can do more than just fuel you through an afternoon slump. It might also power your car.

That's the idea behind a new study that turned used coffee grounds into biodiesel fuel. Coffee will probably never replace petroleum, but discarded cappuccino scraps might someday help reduce our impact on the environment, say the study's authors. They imagine a day when the byproducts of your latte end up in the gas tank of your car -- with hardly any waste left behind.

"It's a very simple two-step process," said Susanta Mohapatra, a chemical engineer at the University of Nevada, Reno. "We can definitely make a big impact on our environment with fuel made out of nature."

Scientists have known for decades that coffee beans contain oil. Mohapatra and colleagues, however, were the first to analyze coffee grounds.

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Used grounds usually end up in landfills, though gardeners sometimes use them as compost material. The scientists collected used grounds from Starbucks, which gives bags of grounds away as part of the company's "Grounds for your Garden" program.

To prepare the grounds for analysis, the team first dried them in an oven. They mixed the resulting powder with a combination of solvents that caused the oil to separate from the solution. They extracted the oil, saving the solvents for the next round of processing. The remains could still be used as compost, ethanol feedstock, and fuel pellets.

"We're not wasting anything," Mohaptra told Discovery News. "It's a recycling process."