Yang Liu holding a vial of coffee ground-derived biodiesel
Coffee already fuels many of us throughout the day — according to figures from Statistics Canada, about two thirds of working-age Canadians are daily java drinkers. If research out of the University of Cincinnati pans out, coffee could start fuelling our cars too.
The research centres around the millions of pounds of spent coffee grounds that get thrown out each year. Yang Liu, an environmental engineering graduate student, gathered a five-gallon bucket of spent grounds from a local Starbucks and extracted the oil for use as biodiesel.
Liu's team is not the first to turn to used coffee grounds as a source of biodisel: a team out of the University of Nevada did something similar in 2008.
But Liu's team added this ingenious twist: after extracting the oil, they recovered the grounds, dried them out, and used them again, this time as a filter to purify the biodiesel by removing methanol, glycerin and other impurities. The fuel that resulted met the ASTM International D6751 standard for biodiesel, which means that it could theoretically be used in an unmodified diesel engine.
Liu and his team weren't done with the coffee grounds just yet though. They took what remained and burned it to produce electricity.
To be clear, the research is still in its early stages: dried coffee grounds aren't quite as effective as commercial fuel filters, and there's no large-scale collection method in place for spent coffee grounds.
But eventually, the researchers say, this development could lead to a plentiful new source of energy which isn't otherwise used in food production. Other biofuels have come under criticism for driving up the price of commodity crops like corn and soybeans due to increased demand (this is often referred to as the "food vs. fuel" dilemma), a problem that doesn't affect waste products like coffee beans.
Plus, of course, using grounds for fuel could help address the significant landfill burden caused by our collective caffeine addiction.