Biodiesel from Waste Coffee Grounds


This article was published by Newsletter, issue #52, 2009-02-01.

Anyone who has experienced the energizing effects of coffee, will not be astonished to learn that researchers have reported that waste coffee grounds could be an inexpensive and environmentally responsible source of biodiesel fuel. Mano Misra, Susanta Mohapatra, and Narasimharao Kondamudi — scientists at the University of Nevada, Reno — published their findings online in the Journal of Agricultural and Food Chemistry, a publication of the American Chemical Society (ACS). They note that used coffee grounds comprise 11 to 20 percent oil, by weight, which is roughly equivalent to that of palm, rapeseed, and soybean sources. Given that coffee growers produce in excess of 16 billion pounds of coffee every year globally, it amounts to 340 million gallons of biodiesel. The use of spent coffee grounds as an energy feedstock, would be an alternative to its usual fate, as a soil conditioner, or as additional waste in our growing landfills.

The researchers confirmed the feasibility of this new feedstock, by collecting waste coffee grounds from a well-known coffeehouse chain, separating out the oil, and then converting all of it into biodiesel, utilizing an inexpensive and eco-friendly process. The resultant fuel — which naturally retains the aroma of coffee — possesses at least three major advantages over traditional biodiesel fuels. Firstly, it does not consume food, unlike corn-based ethanol, since it uses only a waste product. Secondly, it is more stable, as a result of the higher levels of antioxidants in coffee. Thirdly, even the leftover solids can be used as compost or for creating ethanol. The scientists estimate that, in the United States alone, this energy source could generate over $8 million of profit. They intend to develop a modest pilot plant in order to experiment in producing this new fuel.

Critics of coffee-based biodiesel argue that the maximum amount of fuel that could be produced is a tiny fraction of the total amount of gasoline used worldwide. According to motor gasoline data from the Energy Information Administration (EIA) for 2007, the United States alone consumes more than that 340 million gallons of gasoline, in less than half a day. On the supply side of the equation, by some calculations, a single gallon of biodiesel would require 47 pounds of coffee grounds. However, supporters of this new energy source point out that it is not intended to completely replace petroleum-based liquid fuels, but instead to be used in conjunction with all other forms of biodiesel — in other words, to serve as a part of the solution. It also can serve as inspiration to point up the countless untapped sources of alternative fuels that are ecologically sound and sustainable.

Detractors sometimes claim that shipping the spent coffee grounds to a processing plant, would waste energy. But the same trucks that deliver new coffee grounds could just as easily cart away the used ones.

Some critics point out that biodiesel has seen limited adoption in the United States. Yet proponents counter that diesel fuels are used successfully in Europe and Asia, and would work equally well in the United States if state governments ceased raising roadblocks to its adoption. The two largest car markets, California and New York, repeatedly ratchet up diesel standards, making it uneconomic for car makers to try to design, manufacture, and sell diesel vehicles into those states. Thus, it is not a problem of technological limitations, but rather the intellectual (and possibly ethical) limitations of state legislators.

If this potential source of biodiesel sees widespread deployment in the future, it would give new meaning to the phrase "unleaded coffee".

Copyright © 2009 Michael J. Ross. All rights reserved.

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