Ethanol might reign as the king of biofuels, but several companies are betting that a close cousin may overcome some of its shortcomings. Butanol has traditionally been used as paint thinner, cleaner and adhesive, but as a fuel additive it contains more energy than ethanol and could be blended into existing cars at higher percentages. And unlike ethanol, butanol does not eat away at pipes so it doesn''t need to be shipped by truck. That could help the nation meet its aggressive renewable fuels standard of 36 billion gallons of biofuels to be blended into gasoline by 2022. According to the Associated Press, Chemical maker DuPont Co. and oil giant BP PLC are working on a pilot plant in the United Kingdom that will produce butanol from such feedstocks as wheat, corn, barley and rye. The two companies have also teamed with British Sugar to develop a commercial-scale ethanol plant that eventually would be converted to produce butanol once the process is perfected. Butanol has nowhere near the political support of ethanol and it still costs more to produce, but several companies are trying to develop technology that may make butanol cost competitive. Butanol producers to date have used Clostridium acetobutylicum bacteria to munch on a variety of sugary feedstocks to produce acetone, butanol and ethanol. The bacteria can be fed corn, sugar cane or cellulosic plant waste. More scientific research is needed to develop new bacteria strains and enhance yields, and engineers will have to address some challenges. Butanol is heavily toxic to the bacteria that breaks it down, so companies are going to have to move beyond simple distillation methods to extract the substance.