Spanish researchers say they have found an environmentally friendly use for the estimated 4 million tons of olive pits generated as waste by the olive processing industry each year: convert them to biofuels. Reporting in the Journal of Chemical Technology & Biotechnology, scientists from the Universities of Granada and Jaen said they created a biofuel by placing the pits, or stones, in a large pressure cooker and adding enzymes that degrade the pits and produce sugars. The liquid was then fermented to produce ethanol. The researchers reported a yield of 5.7 kg (12.5 pounds)of ethanol for every 100 kg (220 pounds) of olive pits. Using olive pits has a major advantage over corn, sugar cane, and other food-based biofuels because it uses inedible food waste and does not require planting new fields. The researchers said that although the number of olive pits available worldwide is not huge, their conversion to ethanol demonstrates the advantages of using food and forestry wastes in biofuel production.