Poor coffee grounds. The quintessential garbage component (think about it: have you ever seen a picture of “garbage” without old coffee grounds in it, right between the crumpled Chinese takeout container and the sprawled banana peel?), the best that soggy brown pile could aspire to was a trip to the compost bin.
But those cold grounds may soon be a hot commodity. As reported in the Journal of Agricultural and Food Chemistry, coffee grounds show promise as a cheap, renewable, widely available source of biofuel. The grounds you dump in the trash still contain 11-20 percent oil, by weight. This is comparable to biofuel crops like soybeans, palm, and rapeseed, but superior in that it capitalizes on a waste product rather than organics cultivated specifically for processing into fuel (which requires a lot more energy and expense, not to mention land). Coffee grounds could supply an estimated 200-350 million gallons of biodiesel per year, worldwide.
And with two Starbucks locations on every corner in the known universe, it won’t be hard to find a pump.