Coffee dregs can be used to produce biodiesel. That is the result of an experiment of the Polytechnic School's chemical engineering department at the University of São Paulo. Brazil is the world's leading coffee producer, second in coffee consumption and generates a great deal of waste that until now went unutilized.

The process involves extracting the essential oil of the dregs using ethanol as a solvent. Then the oil is put in contact with an alkaline catalyst that triggers a chemical reaction called transesterification — which produces biodiesel.

“We suggest this method for small agricultural communities for the production of their own biodiesel as a fuel for machinery. Producing at the industrial scale depends on educating the population for selective waste disposal,” Denise Moreira dos Santos, head of the study, told Tierramérica.