- Dec 30, 2006
Biobutanol - The Other White Meat
David Ramey is no chicken. Once he decided butanol could benefit from a decent advertising campaign, he flew the coop (A.K.A. Blacklick, Ohio) in the summer of 2005 and drove his unmodified 1992 Buick across America fueled by 100% butanol. Like pork is to chicken, butanol is to ethanol. Its virtues are overshadowed by the rising star of the E85 ethanol juggernaut. So in good conscience, we can refer to butanol as "the other white meat". Calls hawking the myriad benefits of butanol have heretofore been drowned out by the thunder of the corn lobby and the politically expedient clamor for ethanol production as an "alternative fuel" to increase our country's energy independence. But the times they may be a'changin' and Ramey's trip might just be the Paul Revere wake-up ride for a new alternative fuel invasion.
"This demonstration-test-drive was the culmination of my work to demonstrate to my colleagues that butanol definitely works as a superior alternative fuel to ethanol," Ramey told AutoblogGreen. But we need to face facts: Butanol is the toe-headed stepchild of the alternative fuel family. But spend more than one minute with Ramey and he'll have you wondering why we aren't jumping on the butanol bandwagon with all guns blazing
After six years of work on a grant from the Deptartment of Energy, he developed an economical method of making butanol by a fermentation process using corn, biomass or cheese whey. Can you say "Little Miss Muffett"? The conventional fermentation process for making biobutanol yields a number of products as well as butanol: acetic, lactic and propionic acids, acetone, isopropanol and ethanol production. Ramey's fermentation only produces hydrogen, butyric acid, butanol and carbon dioxide, and nearly doubles the butanol yield from a bushel of corn from 1.3 to 2.5 gallons per bushel - equivalent to corn ethanol's fermentative yield, but with higher heat content and hydrogen as a co-product. According to Ramey, his butanol production process yields about 42 percent more energy from a given amount of feedstock than existing ethanol production methods. Sounds promising, no? True geeks may enjoy perusing Dave's co-authored paper entitled "Effects of Butyrate Uptake and Long-term Stability of a Fibrous Bed Bioreactor on Continuous ABE Fermentation by Clostridium acetobutylicum" by Wei-Cho Huang, David E. Ramey, Shang-Tian Yang.
So what's the deal with butanol and why is it playing second fiddle to its ethanol cousin? Butanol serves up a big buffet of benefits. Let's step up to the table and see what's on the menu.
What is butanol anyhow? Butanol is also called butyl alcohol (and is named biobutanol when produced biologically), is an alcohol with a 4-carbon structure and the molecular formula of C4 H10 O. It can be produced from petroleum or from biomass. Of course, it's the biomass variety that's of keen interest to AutoblogGreen readers and to this author as well. Butanol is primarily used as a solvent, as an intermediate in chemical synthesis, and as a fuel. It has double the carbon amount of ethanol, which equates to a 25 percent increase in harvestable energy (BTUs). Loosely translated, this means you get energy in the form of butanol plus energy in the form of hydrogen from the fermentation involved in producing biobutanol. The fermentation can use corn, corn byproducts, grass, leaves, agricultural waste and other biomass.
Butanol can be blended with traditional unleaded gasoline just like ethanol, but it goes one step better than its ethanol cousin insofar as it can be combined with gasoline in larger concentrations than those of ethanol-gasoline blends. Butanol can also be blended with ethanol itself to reduce ethanol's evaporation rate. In addition, E85 (15 percent unleaded gasoline and 85 percent ethanol by volume) requires upgrades to the fuel system due to the corrosive nature of ethanol. Butanol can be used undiluted as a vehicle fuel without changing the components of the gasoline vehicle. (Note: some modifications such as increasing the amount of fuel injected will optimize engine performance when running on butanol, but modifications are not required to run successfully on butanol - Ramey's Buick was not modified for the cross-country trip.) What about diesels? Sorry diesel fans. Butanol's a non-starter as a diesel fuel.
Butanol yields an impressive 104,800 BTU/gallon far surpassing the meager 84,250 BTU/gallon of ethanol. Gasoline contains about 121,000 BTUs/gallon. This means the butanol in your Otto cycle internal combustion engine will yield fuel consumption close to that of gasoline. E85 increases fuel consumption by about 10 percent or more. The net energy released per air fuel ratio is higher for butanol than that of gasoline.
Butanol burns as clean or cleaner than E85. During Mr. Ramey's 2005 cross-country trip, butanol surpassed all the minimum emission standards in 10 states at the emission testing stations where he stopped. Test results in the 10 states duplicated the results at the Ohio EPA, Springfield test facility. With over 60,000 miles on his Buick, butanol reduced hydrocarbons emissions by 95 percent, carbon Monoxide to 0.0 percent, and nitrogen oxides by 37 percent.
Butanol is less corrosive and evaporates slower than ethanol. It has a Reid Value of 0.33 psi, which is a measure of a fluid's rate of evaporation. Gasoline's is 4.5 psi and ethanol's 2.0 psi. Unlike ethanol and hydrogen, it can take advantage of existing fuel distribution infrastructure. It does not have to be stored in high pressure vessels like natural gas, and can be (but does not have to be) blended (10 to 100 percent) with any fossil fuel. Butanol can also be transported through existing pipelines for distribution since it is less corrosive than ethanol and is less susceptible to separation in the presence of water. Butanol can help solve the hydrogen distribution infrastructure problems faced with fuel cell development. The employment of fuel-cell technology is held up by the safety issues associated with hydrogen distribution, but butanol can be very easily reformed for its hydrogen content and can be distributed through existing gas stations in the purity required for either fuel cells or vehicles.
History of Butanol
Production of industrial butanol and acetone via fermentation, using a bacterium called Clostridia acetobutylicum, started in 1916, during World War I. Chime Wizemann, a student of Louis Pasture, isolated the microbe that made acetone. England approached the young microbiologist and asked for the rights to make acetone for cordite. Up until the 1920s acetone was the product sought, but for every pound of acetone fermented, two pounds of butanol were formed. A growing automotive paint industry turned the market around and by 1927 butanol was the sought after primary product and acetone was bumped to byproduct status.
The production of butanol by fermentation declined from the 1940s through the 1950s because the price of petrochemicals dropped below that of starch and sugar substrates such as corn and molasses. The labor intensive of batch fermentation system's overhead combined with the low yields contributed to butanol falling out of favor. Fermentation-derived acetone and butanol production all but ceased in the late 1950s.
In the 1970s the primary focus for alternative fuels was on ethanol. People were familiar with its production and did not realize that removing water (a very energy-consuming step) was necessary in order to blend it with fossil fuels. Not much consideration was given to the difficulty of distribution; ethanol cannot be transferred through the existing pipeline infrastructure. The market preference for ethanol, a lower-grade, corrosive, hard-to-purify, dangerously explosive, and very evaporative alcohol is the result. Ethanol is still subsidized by the government, and without subsidies it is more expensive than gasoline. Over the past 30 years, despite subsidies, the very energy-intensive ethanol production has not solved our fuel, power or clean-air requirements.
Biobutanol Bumps in the Road
OK, biobutanol sounds good. It could be used in gasoline-electric hybrids for an environmental one-two punch. It won't do a thing for diesels. Currently no production vehicle is known to be approved by the manufacturer for use with 100 percent butanol. So we'll have to get the lawyers on board. The current party line reads something like this: "The use of butanol in a vehicle which is not approved for this is not recommended as it may cause damage to the vehicle."
If you want to split hairs, using biobutanol as a substitute for gasoline requires fuel-flow increases to match the combustion characteristics of gasoline. Another minor annoyance is that biobutanol may cause erroneous gas gauge readings in vehicles with capacitance fuel level gauging. The viscosity of biobutanol is much higher than for gasoline or ethanol, which could have negative effects on the fuel system. Biobutanol's viscosity is 3.64 centistrokes vs. 0.4-0.8 centistrokes for gasoline. Water is 1.0 centistrokes in comparison.
Cost is the real speed bump. Current prices for traditionally produced butanol (from petroleum) are about $3.50/gallon and up. Similar to its cousin, ethanol, biobutanol is a killer product in search of a killer price. Breakthrough production processes like David Ramey's may be just what the fiscal doctor ordered.
The tide may indeed be turning in biobutanol's favor. Two industrial heavyweights, Dupont and British Petroleum announced in June of 2006 they had joined forces to produce biobutanol from sugar beets. The first phase of the DuPont-BP venture consists of using existing technology to convert sugar beets into 30,000 tons, or 9 million gallons, of biobutanol annually at British Sugar's facility in Wissington, England, east of Cambridge. Check out the details here.
"We believe the time is right for this science and we can help grow the market for biofuel," said DuPont chairman and chief executive officer Charles Holliday. "By getting it out in the pump, letting consumers buy it ... I think that will help government get behind it," Holliday said.
The second phase of the venture involves developing a genetically-modified microbe, or "ultimate bug," as the catalyst for new technology to significantly improve the conversion ratio in processing feedstocks into biobutanol, boosting fuel yield and concentration. DuPont said it hopes to have the "generation 2" biocatalyst ready by 2010, but that there currently are no plans for a production facility in the U.S.
"We believe the opportune time to introduce this into the U.S. would be when the Gen 2 organism is available," DuPont chief innovation officer Thomas Connelly.
"Transportation is an important area to address since it accounts for around 20 percent of global emissions, and in the short- to medium-term, increased blending of bio-components represents one of the few real options for progress in this area on a global scale," said BP chief executive officer Lord Browne.
Praise that Lord and pass the biobutanol. Bring it on I say. The Dupont/BP timetable calls for biobutanol to be marketed in the UK sometime in 2007. For advocates like David Ramey, commercial scale biobutanol can't come to the U.S. soon enough.
Read more about butanol: