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April 15, 2010 Volume 31, No. 27

Coffee beans to biodiesel

MU students recently collected used coffee grounds and turned the oil from them into biodiesel. Their project was part of ongoing research into using alternative feedstocks such as vegetable oils, used cooking oils and gasified shredded tires to produce biodiesel fuel. Biodiesel from these treated feedstocks is fed into diesel test engines to measure performance and efficiency.

The oil in coffee grounds is extracted by a standard method that uses hexane as a solvent. The oil content of spent coffee grounds is almost 14 percent. “The properties of the coffee oil are similar to the properties of soybean oil, the major source of biodiesel,” says Bulent Koc, assistant professor of agricultural systems management. Solids remaining after the conversion can be converted to ethanol or used as compost.