Revived technique could yield diesel fuel

A long-abandoned fermentation technique once used to make explosives can be used to produce renewable diesel fuel to replace fossil fuels, U.S. researchers say. Chemists and chemical engineers at the University of California, Berkley, said they've produced diesel fuel from the products of a bacterial fermentation process discovered nearly 100 years ago. Those products can extracted and catalytically altered to make a fuel that burns like diesel, they said. The fermentation process was discovered in 1914, around the start of World War I, and allowed Britain to produce acetone needed to manufacture cordite, used as a military explosive to replace gunpowder. The process employs the bacterium Colostrum acetobutylicum to ferment sugars into acetone, butanol and ethanol. A catalyst then converts the ideally proportioned brew into a mix of long-chain hydrocarbons that resembles the combination of hydrocarbons in diesel fuel. The resulting product was found to burn as well as normal petroleum-based diesel fuel. While the fuel's cost is still higher than that of diesel or gasoline made from fossil fuels, the process would drastically reduce greenhouse gas emissions from transportation that contribute to global climate change, the researchers said. "Diesel could put Clostridium back in business, helping us to reduce global warming," biomolecular engineering Professor Douglas Clark said. "That is one of the main drivers behind this research."