Researchers from the University of Nevada, Reno, have discovered that coffee can be turned into an alternative fuel other than caffeine: biodiesel. And you can have your coffee and drink it too. No need to use the fresh stuff, old grounds are more than up to the task, according to material scientist Mano Misra and his colleagues.

Even after being subjected to the rigors of brewing, roughly 15 percent of the weight of dried coffee grounds is oil, which, much like palm and soybean oil, can be converted into biodiesel. The coffee has the added benefit of not being a food source, like palm oil and soybeans.

Nevertheless, more than 16 billion pounds of coffee are produced globally every year, according to the U.S. Department of Agriculture. Misra estimates that the grounds from that haul could be used to make as much as 340 million gallons of biodiesel. For their part, the researchers turned grounds donated by Starbucks into biodiesel that had the added advantage of smelling like a fresh cup o' Joe.

The researchers note that coffee's high proportion of antioxidants, such as chlorogenic acid, acts as a natural preservative for the resulting biodiesel, preventing it from going bad like other forms of biofuel and even petroleum diesel can. The researchers hope to set up a pilot plant to convert grounds into biodiesel next year and estimate that, for its part, Starbucks in the U.S. alone could turn a profit of $8 million a year from the process, assuming that both the biodiesel and leftovers of the process can be sold.

To chill this simmering cup a bit: the U.S. Department of Energy says that the U.S alone burns 40 billion gallons of diesel a year, meaning that converting all the grounds in the world wouldn't even contribute 1 percent of U.S. diesel consumption. Still, it's an idea that could perk you up.

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