Butanol Could Power Up Biofuel

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.

By Dirk Lammers, Associated Press 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, says Andy Aden, a research engineer at the National Renewable Energy Laboratory. "Our existing infrastructure has too many bottlenecks, and it's just not going to cut it," Aden insists.
'A Fair Way Off'
Chemical maker DuPont Co. and oil giant BP 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. According to DuPont Vice President John Ranieri, the pilot plant should be operational by next year, and the companies are working to make butanol cost-competitive with grain ethanol by 2010. "Once we are commercial with biobutanol, we intend to combine our technologies to make biobutanol from non-food feedstocks," Ranieri says. Moreover, Aden believes that butanol as a fuel holds promise, but the technology is still in a low level of development: "Despite what companies are saying, it's still a fair ways off."
Backing From Branson
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. Gevo Inc., an Englewood, CO-based company backed by venture capitalists Richard Branson and Vinod Khosla, says that it's solving that problem with a form of E. coli bacteria. Butanol producers to date have used Clostridium acetobutylicum bacteria to munch on a variety of sugary feedstocks to produce acetone, butanol and ethanol. By substituting an E. coli derivative developed by scientists at the University of California in Los Angeles, Gevo is able to produce only isobutanol, says Pat Gruber, the company's chief executive. The bacteria can be fed corn, sugar cane or cellulosic plant waste. "That bug eats most anything thrown at it, so it's already shown it can do cellulosics," Gruber admits. "All I need is to have some low-cost cellulosic supply available." Gruber says the process is already underway at a small 20,000-gallon-per-year pilot plant in Colorado. The next step is to partner with ethanol plant designer ICM to build a larger scale facility at ICM's biofuels research center in St. Joseph, MO. Gevo's business model is to take existing ethanol plants and retrofit them into butanol plants, a transformation Gruber estimates would cost between 25 and 30 cents per gallon in capital. "All we're doing is changing the bug, adding some skids of equipment. Voila. It is now a butanol plant," he says.
Several Challenges
Aden believes that the concept is feasible, but that butanol faces several challenges if production costs are to be reduced. More scientific research is needed to develop new bacteria strains and enhance yields, plus engineers will have to address some other 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. But Aden sees butanol eventually providing another choice for the consumer who pulls up to the pump. Gruber believes butanol could change the biofuels market. Removing water from isobutanol produces isobutalene, which can then be converted into iso-octane, which can be made into gasoline, diesel and jet fuel. So a Midwest biorefinery that now makes ethanol could one day deliver homegrown gasoline right to the pump, he says.