Biobutanol can be produced by fermentation of biomass by the A.B.E. process. The process uses the bacterium Clostridium acetobutylicum, also known as the Weizmann organism. It was Chaim Weizmann who first used this bacterium for the production of acetone from starch (with the main use of acetone being the making of Cordite) in 1916. The butanol was a by-product of this fermentation (twice as much butanol was produced). The process also creates a recoverable amount of H2 and a number of other by-products: acetic, lactic and propionic acids, isopropanol and ethanol.
Biobutanol can also be made using Ralstonia eutropha H16. This process requires the use of an electro-bioreactor and the input of carbon dioxide and electricity.[5]
The difference from ethanol production is primarily in the fermentation of the feedstock and minor changes in distillation. The feedstocks are the same as for ethanol: energy crops such as sugar beets, sugar cane, corn grain, wheat and cassava, prospective non-food energy crops such as switchgrass and even guayule in North America, as well asagricultural byproducts such as bagasse, straw and corn stalks.[6] According to DuPont, existing bioethanol plants can cost-effectively be retrofitted to biobutanol production.[7]
Additionally, butanol production from biomass and agricultural byproducts could be more efficient (i.e. unit engine motive power delivered per unit solar energy consumed) thanethanol or methanol production.[8]
Company Retrofitting Ethanol Plants for Biobutanol
Posted on October 7, 2009 by Cindy Zimmerman
A Colorado-based company is working to develop a fleet of biorefineries based on retrofitting existing ethanol plants to produce biobutanol.
Last week, Gevo, Inc. announced the start up of the first biobutanol demonstration plant designed from retrofitting an existing demonstration scale ethanol plant in St. Joseph, Missouri. The company is using the plant to demonstrate the viability of its technology for retrofitting existing ethanol plants to make biobutanol, which can be blended directly into gasoline and be used to make renewable hydrocarbons (“green gasoline”), diesel and jet fuel, chemical intermediates and biobased plastics.
NEARLY a decade after the adoption of federal renewable fuel standardsled to a sharp increase in production of ethanol, some producers in the Corn Belt are considering making a different fuel. The fuel, butyl alcohol, or butanol, is worth more to refiners because it has more energy than ethanol, is easier to handle and more of it can be blended into each gallon of gasoline. But producing it will require costly retrofitting of ethanol plants, and plant capacity will be reduced.
Several companies are leading the push for butanol, including Gevo of Englewood, Colo., and Butamax Advanced Biofuels, a joint venture of BP and DuPont based in Wilmington, Del. They have developed ways to make butanol the same way ethanol is made, through yeast-based fermentation and then distillation.
“There are few if any new biofuel molecules that can be made from an existing ethanol plant,” said Paul Beckwith, chief executive of Butamax. “The beauty of what we’re offering is, it’s so similar.”
Continue reading the main storyRELATED COVERAGE
As U.S. Aid to Clean Energy Dwindles, Pondering What Could ComeOCT. 23, 2012
Excelerate Energy Hopes to Be an International Natural Gas SupplierOCT. 23, 2012
New butanol-specific plants could also be built, he said, including ones that, like cellulosic ethanol plants, use switch grass or other nonfood raw materials rather than corn.
Butamax is producing butanol at a demonstration plant in Hull, England. And in the United States, it has organized an alliance of ethanol producers who are considering making the shift. The idea, Mr. Beckwith said, is to convert many plants simultaneously, beginning in 2013.
Gevo began making butanol at a 22 million gallon a year ethanol plant in Luverne, Minn., in May, although it has now stopped production.
“We’re currently in the process of switching back to ethanol while we give engineering team to make some improvements,” said Chris Ryan, Gevo’s president.
The two companies also are involved in a legal dispute over patents that is working its way through the courts.
Brian D. Kletscher, chief executive of Highwater Ethanol in Lamberton, Minn., a member of Butamax’s alliance, said his company would talk with gasoline refiners before making a final decision to convert its plant. “We see a potentially valuable commodity here,” Mr. Kletscher said. “It could allow maybe a 20 to 30 percent increase in our margins. That’s the No. 1 thing that sparks us to look at it.”
Last year, Highwater used nearly 19 million bushels of corn to produce about 55 million gallons of ethanol, which was shipped by rail tankers to refineries on the East Coast. If the company decided to go ahead with conversion, the work would take up to a year, Mr. Kletscher said, although the plant would be shut only about two weeks.
Butamax estimates that converting an ethanol plant will cost 20 percent to 30 percent of a plant’s original price tag — perhaps $10 million to $15 million for one the size of Highwater’s, more for larger facilities. The conversion will also reduce a plant’s capacity about 20 percent, the company said, but the greater value of butanol should more than make up for the lost volume.
Mr. Ryan said Gevo’s conversion costs would be somewhat higher, at least initially. Most of the butanol produced at Luverne was sold to the chemical company Sasol, he said. Butanol has long been used in the chemical industry as a solvent.
Advertisement
Continue reading the main story
Advertisement
Continue reading the main story
But Mr. Ryan said Gevo was withholding some of the butanol to develop fuels, and it had a small contract with the Air Force to convert butanol to jet fuel.
Butanol offers several advantages to gasoline refiners, Mr. Beckwith said. It contains about 30 percent more energy than ethanol, and it can be blended with gasoline at a higher percentage — Butamax recommends 16 percent butanol, compared with the current 10 percent standard for ethanol. That would allow refiners to more quickly meet the Environmental Protection Agency’s renewable fuel standards, which were adopted in 2005 and mandate that transportation fuels contain increasing amounts of alternative fuels over time.
Because ethanol evaporates relatively easily, refiners have to remove some of the lighter components from their gasoline so the blended product meets air-quality standards. Butanol evaporates less readily, so refiners can leave many of these more volatile components in, saving money.
Michael McAdams, president of the Advanced Biofuels Association, an industry group, said butanol was a “drop-in” fuel, able to be used with existing gasoline pipelines and other equipment because it does not have a tendency to take up water, as ethanol does.
“It’s more fungible in the existing infrastructure,” he said. “You could blend it with gasoline and put it in a pipeline — no problem.”
Butanol would also help producers get around the so-called blend wall, Mr. McAdams said. Given the amount of gasoline used annually in the United States, and the blending limit of 10 percent ethanol, producers are close to their capacity limits, now about 13 billion gallons of ethanol a year.
With the 10 percent limitation, “you don’t have enough gasoline to put the ethanol in,” he said. “You don’t have that problem with butanol.”
This is the first time that an existing ethanol operation has been successfully retrofitted to produce biobutanol instead of ethanol. ICM’s pilot plant at St. Joseph has been designed and constructed as a reduced scale replica of a dry-milled ethanol production process. Additionally, Gevo’s biobutanol has higher energy content than ethanol and a lower Reid Vapor Pressure (RVP) – which means lower volatility and evaporative emissions. Importantly, standard automobile and small engines can run on biobutanol blended into gasoline at any ratio.
The retrofit of the pilot plant was completed in less than three months and the company says it also represents the first step along the route to produce cellulosic biobutanol which will be possible once biomass conversion technology becomes commercially available.
Before you get too far down the road on the retrofit, you need to look at the market into which the butanol is going. If it is fuel, the economics might not work out. However, if you can identify compounds that can be easily made from butanol (i.e. using basic chemical engineering processes) then the economics become much better. A group of chemical engineers or chemists should be able to identify these compounds and processes.
Doing business with the petroleum companies is a financially risky proposition. When we started working in this area, the business strategy was to find compounds that could easily be added at the production site that significantly increase the value. Then sell them to industries that need them and are tired of dealing with the petroleum companies. There are multiple compounds in this area... but you need a chemist and an chemical engineer to get an idea of which to make.