Waste coffee grounds can provide a cheap, abundant, and environmentally friendly source of biodiesel fuel, according to a study by researchers at the University of Nevada-Reno.
With world coffee production at more than 16 billion pounds per year, the scientists estimate that spent coffee grounds could potentially add 340 million gallons of biodiesel to the world’s fuel supply.
For the study, the team collected grounds from Starbucks facilities in Reno. They used an inexpensive process to convert 100 percent of the oil from the grounds into biodiesel. The resulting coffee-based fuel—which smells like java—is more stable than traditional biodiesel due to coffee's high antioxidant content, according to the researchers. Solids left over from the conversion can be converted to ethanol or used as compost.
The researchers plan to develop a small pilot plant to produce and test coffee-biodiesel in 2009.