While coffee often perks up our morning or mid-day slumps, used coffee grounds are often left to sit in landfills. In a study published in the Journal of Environmental Chemical Engineering, researchers found that rather than going to waste, used coffee grounds can be efficiently repurposed as an environmentally-friendly biofuel.
Spent coffee grounds contain up to 20 percent lipids and lignocellulose (dry plant material), which can be used as bioenergy. Though methods of extracting these materials have existed for some time, the researchers in the new study described a more efficient method based on a process called “in situ transesterification.” Through the method, oils are extracted from the coffee grounds and converted into biodiesel by mixing them with hexane at 140 degrees Fahrenheit. After one to two hours, the hexane is then evaporated to leave only the oil. Other materials, such as methane, a catalyst, and a glycerol by-product, are then added to make the biofuel.
“Our findings reveal that in situ transesterification, a single step biodiesel production process with significant cost savings and potential might provide a new industrial potential for the recovery of fuel from spent coffee grounds,” the study said.