Coffee grounds — currently wasted or used as garden compost — could become a cheap and environmentally friendly source of biodiesel and fuel pellets, says a study. Spent coffee grounds contain 11–20% oil, depending on their type. "This is competitive with other major biodiesel feedstocks such as rapeseed oil (37–50%), palm oil (20%), and soybean oil (20%)," say researchers writing in the Journal of Agricultural and Food Chemistry
Scientists at the US-based University of Nevada, Reno, used an inexpensive process to extract oil from the leftovers of making espressos, cappuccinos and other coffee preparations from a multinational coffeehouse chain. This oil was then converted into biodiesel, which could be used to fuel cars and trucks. The world's coffee production is more than 7.2 million tonnes per year, according to US Department of Agriculture figures cited in the study. This could yield about 340 million gallons of biodiesel, say the researchers.
Source: Coffee as a source of biofuels