From coffee shop to biodiesel source in one step

Spent coffee grounds have been turned into biodiesel by researchers from Portugal and Spain, who combined two separate processes to produce the biodiesel in one step.

Spent coffee grounds contain up to 20 weight per cent lipids, most of which are triglycerides that can be extracted and converted by transesterification into the fatty acid methyl esters that make up biodiesel. Pedro Simões from the New University of Lisbon and colleagues produced the esters in a 93 per cent yield, combining the extraction and transesterification processes in one step.