Students at the University of Missouri-Columbia collected used coffee grounds to employ as fuel stock to make biodiesel fuel. (Soybeans are the main fuel stock for conventional biodiesel production). A professor there said of their research, “the properties of the coffee oil are similar to the properties of soybean oil, the major source of biodiesel.”
Used coffee grounds have about 14 percent oil content. It’s the oil that is used for biodiesel production. The process for converting the oil usually is transesterification. This process was used with the coffee grounds oil, in the presence of hexane. Hexane helps separate the oil from other material in the oil. Once the oil is extracted it can be refined further, and the hexane can be recycled and used again.
World production of coffee from 2009 was estimated to be 127,000,000 60 kilo bags, or over 16 billion pounds. The top producers were Brazil, Colombia and Vietnam. (If you want to look at more coffee stats, visit the International Coffee Organization site.)
The MU press release doesn’t state the amount of biodiesel that was made from the coffee grounds. The US is a very large consumer of coffee so one might assume there could be a large potential for biodiesel production. However, the article does say about 340 million gallons of biodiesel per year could be produced from coffee grounds some day. Even that amount represents a tiny fraction of yearly fuel consumption. A research paper on using sewage for biodiesel says 1.8 billion gallons of biodiesel is still less than one percent of national petroleum consumption.
So does that mean coffee grounds won’t matter? No, it only means they probably won’t be a major component of total yearly fuel production. Although they might help produce biodiesel for companies with large amounts of coffee grounds, to assist in the powering of their own fleets, and all options are worth exploring when we import so much of our petroleum currently.
Image Credit: cgfan