Researchers are exploring the potential of olive stones, otherwise a waste product of the olive processing industry, as a substrate for bioethanol production. The stones are rich in polysaccharides (cellulose and hemicellulose) that can be broken down into sugar and then fermented to produce ethanol.

In a pilot study, the olive stones were pre-treated using high-pressure hot water before the addition of enzymes which degrade plant matter and generate sugars. The hydrolysate obtained from this process was then fermented with yeasts to yield about 5.7 kg of ethanol per 100kg of olive stones.