From Grounds to Gas

Coffee grounds: one of the most prolific wastes on campus.  Sodexo sells coffee through many different vendors, and between those sales and the dining hall consumption, our coffee consumption produces about 415 pounds of used coffee grounds every week.  Currently, these grounds are composted to make fresh soil, but their usefulness could be extended further.  Elizabeth Conger, a junior environmental engineering major, is researching a process to produce biodiesel from the Wildcats’ favorite energy booster. Coffee grounds contain about 15% lipid content per mass, and specific lipids known as fatty acids can be chemically converted to fatty acid methyl esters, the components of biodiesel.  These chemical reactions require nothing more than common laboratory reagents, such as lye and hydrochloric acid, and heat. The remaining 85% of coffee ground biomass can still be used in compost, but the extracted fatty acids can help keep our university running using a little less gasoline. The project is still in its infancy, but Elizabeth is conducting experiments to provide the greatest yields from the reactions, as well as identifying methods to collect and process grounds on a university-wide scale. In the future, if you smell a whiff of coffee in the exhaust of a Northwestern shuttle, you may rest assured that your late-night caffeine run helped provide fossil fuel-free transportation to campus.


By: Elizabeth Conger, Northwestern University Class of 2015


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