Chemical engineers at UC Berkeley have created a new, cleaner fuel out of an old concoction that was once used to make explosives.

The fuel, which uses a century-old fermentation process to transform plant material into a propellant, could eventually replace gasoline and drastically cut down on greenhouse gas emissions, according to the team of Berkeley scientists.

"It's a much more efficient way of (creating renewable fuel) than many of the other products being considered," said Harvey Blanch, a professor of chemical engineering at Berkeley. "This product is one that may be closest to commercialization."

The discovery, published in the journal Nature, means corn, sugar cane, grasses and other fast-growing plants or trees, like eucalyptus, could be used to make the propellant, replacing oil.

The process uses a fermentation system discovered around 1914 by Chaim Weizmann, a chemist who later became the first president of Israel. Weizmann used a bacterium called Clostridium acetobutylicum to ferment sugars and turn them into acetone, butanol and ethanol. The process, dubbed ABE, allowed the British to manufacture cordite and make explosives used during World War I.

The process was later used to manufacture synthetic rubber, but that was unnecessary after petroleum became widely available. The last U.S. factory using the process to produce acetone and butanol closed in 1965.

The research into creating a diesel substitute is part of a 10-year development program by the Energy Biosciences Institute, a collaboration among UC Berkeley, Lawrence Berkeley National Laboratory and the University of Illinois at Urbana-Champaign. The research, paid for using $50 million a year from the British oil company BP, has been going on for five years.

Blanch and Douglas Clark, a professor of chemical and biomolecular engineering, extracted the acetone and butanol from the fermentation mixture, according to their paper. Their co-author, chemistry Professor Dean Toste, then created a catalyst that converted the brew into a mix of hydrocarbons similar to those in diesel fuel.

The resulting substance burns as well as petroleum-based fuel and contains more energy per gallon than ethanol, according to the study. It can be produced using a variety of renewable starches and sugars that can be grown in crops.

"You can take a wide variety of sugar sources - from corn, sugar cane, molasses to woody biomass or plant biomass - and turn it into a diesel product using this fermentation process," said Blanch, adding that about 90 percent of the raw material remains in the finished product, reducing the loss of carbon. "Grasses are also a possible source. Eucalyptus could also be used. Anything that's fast-growing."

The blend could be adjusted for summer or winter driving, according to the researchers, who predicted it will be five to 10 years before the fuel is ready to be mass-marketed.

Blanch said it will probably take five years for the fuel to be perfected and become ready to be sold to the public. It could take another five years, he said, to develop a system that would produce the product on a scale large enough to meet the demand of the motoring public at a low enough cost to compete with oil-based products.

The expectation in California is that it will be used initially for niche markets, like the military, and eventually in trucks, trains and other vehicles that need more oomph than hybrid or battery power can provide.