University of Cincinnati researchers report they've successfully converted waste coffee grounds into energy sources, including biodiesel and activated carbon.
Grounds left over from brewing one of the world's most popular beverages are estimated at more than 1 million tons per year in the United Statesalone, with the majority of it getting dumped into landfills, the university said in a release Monday.
In 2010, researchers began recovering waste coffee grounds from a Starbucks store on the university campus, removing oils they then converted into biodiesel fuel. The coffee grounds were subsequently dried and used to further purify the biodiesel.
The oil content in the grounds was between 8.37 and 19.63 percent, the researchers said, and the biodiesel made from coffee oil meets international fuel standards with less emissions of carbon monoxide, hydrocarbons and particular matter than petroleum diesel.
Using coffee grounds to produce biodiesel would not only open landfill space, they said, but would create biodiesel from a natural product that's not also in high demand as a food source, such as corn and soybean crops used to manufacture biodiesel.