Recycle coffee grounds to curb global warming

1/23/2008 | By: John Trent  |

In the not-too-distant future, University researcher Manoranjan Misra can envision a day when customers might pull into the drive-through at Starbucks for a cup of coffee ... and then fill their cars with biodiesel made from the same coffee grounds that produced their tasty latte. Misra, a professor of chemical and metallurgical engineering, has developed a novel process - believed to be the first of its kind in the country - to extract high-quality biodiesel from spent coffee grounds. Misra’s process has important implications in the world’s efforts to combat global warming through the creation of alternative fuels such as biodiesel. What sets his work apart from other biodiesel efforts is the high quality of the biodiesel extracted from coffee grounds. The process also utilizes an inexpensive waste product, thus reducing overall cost. “We have found that biodiesel created from spent coffee grounds is stable over a longer period of time than other forms of biodiesel that have been created from feed stocks such as soy and corn,” Misra said. “Biodiesel from spent coffee grounds is a low-cost ‘green’ form of fuel that shows a significant reduction of carbon dioxide emission. It’s an excellent source for biodiesel.” Using Starbucks as an example, Misra said that the coffee-making giant generates more than 200 million pounds of spent coffee grounds per year in the United States. “We estimate that this could produce almost 3 million gallons of biodiesel per year,” Misra said. Misra’s process, which has been patented, involves two simple steps: the extraction of oil from the spent coffee grounds, and then the conversion of the oil to biodiesel. He said that the produced oil is a triglyceride, which is the chemical form in which most fat exists in food. The triglycleride-rich oil easily lends itself to biodiesel conversion, and serves as an agent to reduce carbon dioxide emissions when it is burned as fuel. Removal of one pound of triglyceride from coffee grounds would reduce about three pounds of carbon dioxide, making it a highly effective agent in battling the continued accumulation of greenhouse gases, Misra said. Worldwide, the potential for the new “coffee” biodiesel is great, Misra said. He noted that about 15 billion pounds of coffee is consumed in the world; of this, the new technology could potentially produce more than 200 million gallons of biodiesel. In northern Nevada alone, about 70 million pounds of coffee is produced at the Starbucks roasting plant in the Carson Valley. Misra said he created the technology almost by accident. “I had left my coffee out one night, and the next morning, I noticed that there was a kind of oil around the edge of the cup,” he said. “Every cup of coffee has it. I decided to do some tests on the oil.” He discovered that the oil, rich in triglycerides, could be easily converted to biodiesel. “The oil still smells like coffee,” he said. “It doesn’t change a lot during the process.”


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