1. Butanol Characteristics
Butanol is an alcohol (colorless liquid with a characteristic odor of fusel oil) containing four carbon atoms (C4H9OH). In addition to butanol, the family of alcohols includes methanol (2 carbon atoms – C2H5OH) and propanol (3 carbon atoms – C3H7OH). “Biobutanol” means butyl alcohol (butanol) produced from plant raw materials.
2. Butanol Applications
Butanol is used as a solvent in paint-and-varnish industry and in the production of resins and plastifiers, as well as in the synthesis of multiple organic compounds. It can be used as a component of traditional fuels or individually as a fuel for transportation vehicles.
3. Raw Materials for Butanol Production
Butyl alcohol (butanol) likewise ethyl alcohol (ethanol) can be produced by:
• processing sugar or starch of agricultural crops (biobutanol of the 1st generation);
• processing plant cellulose (biobutanol of the 2nd generation);
• synthesizing chemical source products (butanol).
Butanol made of biomass is commonly named as biobutanol, although its characteristics are absolutely the same as those of butanol made of oil (chemical raw materials).
4. History of Butanol Production
The industrial production of butanol was launched in 1916. At that time, an ABE (acetone, butanol, ethanol) fermentation method was used involving bacteria Clostridia acetobutylicum. This acetone-producing microorganism was discovered by Haim Weizmann (U.S. Patent #1 315 585). During the World War I, England addressed a young microbiologist requesting to sign away the right on acetone production to be used for making cordite (smokeless gunpowder). The process was employed as along as until 1920-s only for producing acetone. However, during the fermentation process two liters of butanol were received per liter of acetone. One day someone added nitrocellulose to butanol and received a quick-drying lacquer. Three years later, machine building industry modified dramatically the overall market and by 1927 butanol became the key product of ABE process while acetone was considered as a by-product. During the World War II, butanol served as a synthetic rubber.
Thus, in the first half of XX century, biobutanol was made of corn or molasses by fermentation involving Clostridium acetobutylicum. The final products consisted of acetone, butanol and ethanol and, thus, the process was referred to as ABE. By-products of ABE fermentation include hydrogen; isopropanol; acetic, lactic, propionic and butyric acids; carbon dioxide; and, lipids. The need to separate the main fermentation products and to remove by-products is causing an increase of the production cost of each liter of butanol.
Since 1954, the oil prices have been lower than those of sugar as the United States is receiving no more inexpensive sugar supplies from Cuba. As a result, despite the continually growing demand for butanol, the fermentation-based production began to decline. Currently, the most efficient methods for making butanol from oil are halogenalkane hydrolysis and alkene hydrolysis with hydration.
At present time, butanol is used primarily as a solvent for industrial applications. The estimated world market for this product is 350 mln. gallons per year, and the U.S. share of this amount is 220 mln. gallons per year.
5. Butanol as a Motor Fuel
Butanol can replace gasoline as a fuel even to a larger extent than ethanol due to its physical properties, cost effectiveness, safety and because its application does not require any automobile engine adjustments.
The main reason why nobody has considered butanol as an alternative fuel is that its production has never been deemed cost effective. As mentioned above, this product is applied mostly as an industrial solvent and its price is almost three times higher than the gas price. When the traditional fermentation process is used, from a bushel of grain (35 pounds of sugar) it is possible to get only 1.3 gal of butanol, 0.7 gal of acetone, 0.33 gal of ethanol and 0.62 pound of hydrogen. Such butanol production will not be competitive with ethanol production with the product yield of 2.85 gal per bushel. Biotech progress enabled to transform corn and other types of biomass into a rather cost effective source of biobutanol. However, the introduction of industrial-scale production depends on some other factors.
Butanol is generating a larger amount of clean energy per operating cycle than ethanol or methanol and approximately by 10% more than gasoline.
Since new highly effective technologies of biobutanol production have been developed, experts have put emphasis on butanol made of grain considering it as a potential fuel. There is a chance that in the next 10-15 years ethanol will be displaced from its top position.
The success is based on a number of butanol advantages over ethanol, including:
1. Energy content in butanol is 25% higher than in ethanol: 110.000 BTU per gallon of butanol vs. 84.000 BTU per gallon of ethanol. Gasoline contains about 115.000 BTU per gallon.
2. Butanol is safer for use since its evaporation is six times less than that of ethanol and its volatility is 13.5 times lower than that of gasoline. Reid vapor pressure of butanol is 0.33 pounds per square inch (psi), gasoline – 4.5 psi and ethanol – 2.0 psi. As a result, it is more safe to use butanol as oxygenate and no significant variations of proportions in the mixture are required in the summer and winter season. It is used now as oxygenate in the states of Arizona and California and other places.
3. Butanol is a significantly less aggressive substance than ethanol. Thus, it can be transported through the existing fuel pipelines, while for ethanol transportation it is necessary to involve rail or water transport.
4. Butanol can be mixed with gasoline;
5. Butanol can replace gasoline completely, while it is possible to use ethanol only as an additive to gasoline with the maximum share of 85% and only after major engine adjustments. Currently, most of the mixtures contain 10% of ethanol.
6. Butanol production is helpful for resolving issues related to hydrogen supply infrastructure.
7. Modified butanol is characterized by higher energy output (10 watt-hour/g) than ethanol (8 watt-hour/g);
8. No sulfur or nitrogen oxides are released through butanol combustion and it is considered as an additional ecological benefit. Thus, biobutanol is more cost effective vs. ethanol and gasoline mixture, it improves automobile fuel efficiency and increases distance run per unit of the consumed fuel. Biobutanol is produced from the same source products as ethanol – corn, sugar beet, sorgho, manioc, sugar cane, corn stems and other types of biomass, but it can replace gasoline in the equal volume.
6. Development of Butanol Production Technologies of Generation I
6.1. Environmental Energy
ABE fermentation using bacteria Clostridium acetobutylicum is one of the pioneering processes used for industrial butanol fermentation. Based on the application of the above anaerobic microorganisms, such industry as microbiological production was established. However, prior to the introduction of a new strain called Clostridium beijerinkii and the development of a novel technology by Environmental Energy Company, fermentation was a complicated and hardly controllable process.
The shift is initiated by the increase in butyric acid concentration over 2 g/l and the reduction of pH value <5. The traditional ABE fermentation process is characterized by a low butanol yield: about 15% and only occasionally above 25% (1.3 gal per bushel). Butanol production is limited, since at the concentration of 1.0-2.0% butanol is inhibiting cell growth and may interrupt fermentation. Therefore, within the traditional ABE fermentation process, the concentration of butanol usually does not exceed 1.3%. All attempts made over the last 20 years at most enabled to obtain butanol at the concentration less than 2.0%, with the productivity of 4.46 g/l/h and butanol yield less than 25% of glucose weight.
At the beginning of XXI century, Hans Blaschek, a Professor of the Food Microbiology Department, the University of Illinois, isolated a new Clostridium strain. In 2004, Clostridium beijerinkii was selected by the U.S. Department of Energy for gene mapping. The work was performed at the Joint Genome Institute, California. In April 2006, at the conference on bioenergy held in the University of Illinois, Professor Hans Blaschek gave a talk about the remarkable progress achieved in his development of butanol production technology.
Using a genetically modified microorganism - Clostridium beijerinkii patented by him, Hans Blaschek successfully transformed corn into butanol. The Professor received a microbial genome map and used it to initiate fermentation process. Based on the available results of genome analysis he is planning to develop the second generation of Clostridium beijerinkii with anticipated higher effectiveness.
Besides, Professor Hans Blaschek has developed fundamentals of butanol production technology through its extraction from gas. In this case, butanol will be inexpensive and contain no impurities (which could be found in the product if membrane-based technologies are used).
The scientist is planning to scale up the fermentation process of butanol production using the existing strain of Clostridium beijerinkii, identify effective cereal source materials and a type of cereal fibers to be used for butanol production and to create the second generation of microorganisms.
Later on, the company Environmental Energy added two new bacterial strains to the process and offered a number of engineering options and ultimately announced that a full-value technology of biobutanol production has been developed. The Company received a US Patent #5753474 “A continuous two-stage anaerobic fermentation process for producing butanol and other organic solvents involving two different bacterial strains.” The patent is describing a promising technology of efficient and cost effective butanol production. The use of continuously operating doubled bio-reactors with immobilized cells enabled the Company to increase butanol yield to 2.5 gal per grain bushel and additional 0.6 pound of hydrogen as a by-product.
Originally, the development was funded through a federal grant assigned by the U.S. Department of Energy within the program on small business promotion and in collaboration with Dr. S. T. Yang from the University of Ohio who provided a patented bioreactor to the company for these purposes.
The optimization of ABE fermentation process and the production of butanol using butyric acid transformed from carbohydrates substantially increased butanol yield, volume output and concentration. The use of immobilized cultures of Clostridium tyrobutyricum and Clostridium acetobutylicum by Environmental Energy Company ensures the optimal butanol productivity of 4.64 g/l/h and the output of 42% of glucose weight or 2.5 gal per bushel of grain (35 pounds of starch/lactose/sugar).
In contrast to the traditional ABE process, the technology proposed by Environmental Energy is free from such undesired by-products as acetic, lactic and propionic acids, acetone, isopropanol and ethanol. This technology maintains carbon and its final products include carbon dioxide, hydrogen, butyric acid and butanol. The output of butanol has been doubled from 1.3 gal to 2.5 gal per bushel of grain.
In addition, this new technology is generating such by-product as hydrogen which is also an alternative fuel. In view of the availability of such by-product as hydrogen, the new technology enables to generate additionally 42% of energy per grain bushel vs. the traditional method of ethanol production (25% of this difference is made up by butanol and 18% – hydrogen). It is important to emphasize that even with a lack of technical grounds for using hydrogen as an alternative energy source, it is still a valuable chemical required for multiple sections of chemical industry.
Environmental Energy Company has set up a biobutanol production unit in the United States. According to company’s experts, through the operation of this unit biobutanol can be produced from everything growing on the Earth. At first, the company is planning to launch biobutanol production for the market of solvents and later to sell it as an alternative fuel.
6.2. DuPont è ÂÐ
In 2006, BP and DuPont announced about their joint efforts in the production of advanced biofuel putting emphasis on biobutanol. In 2008, the company was informed about fuel testing results, including the following:
• mixtures with high butanol proportion have demonstrated their positive characterisitcs;
• energy density of biobutanol is close to that of nonleaded gasoline;
• biobutanol is not mixing with water.
Earlier in 2008, the companies declared that their partnership was focused on the development of butanol-1 and butanol-2. The latter is called “butanol isomer.” It contains 4 carbon atoms, but alcohol atoms are arranged in a different way. The partnership objective is to develop by 2010 a process of biobutanol production economically equal to the process of bioethanol production. At present, the companies have filed applications for over 60 patents in the following areas: biology, enzymatic treatment, chemistry and final use of biobutanol.
In general, BP and DuPont will invest about US$400M to the construction of a new facility. The facility will initiate bioethanol production, and the second small-scale pilot unit will start biobutanol production. Later, the overall facility could be upgraded for making butanol.
An ethanol producing plant will be set up at the already existing chemical facility of BP. Its construction will be completed by the end of 2009. Its capacity will reach 420 million liters of bioethanol per year. Ethanol will be made of wheat. A pilot line installed at the site will have the capacity of 20,000 liters of biobutanol per year and use various biological sources of plant raw materials, primarily sugar- and starch-containing cultures.
6.3. Fermentation Biotechnology Research
First, the microbiological fermentation process is characterized by one paradoxical feature: though butanol-forming bacteria generate enzymes which convert simple sugars into alcohol, butanol itself is toxic for these microbes. As result of such inhibition by butanol, there is a low alcohol concentration in the fermenting medium. Thus, butanol yeild is reducing and production costs are growing. These challenges occur through the use of highly purified raw materials. When less expensive biological raw materials are used, the additional bacterial inhibitors are produced at the stage of preliminary treatment.
Strategies are being developed to reduce butanol toxicity and increase its output, including several integrated levels in the process of control of microbiological cultures. The overall process developed by Qureshi’s team for butanol production includes the following four stages:
• hydrolysis of hemicellulose and cellulose to obtain simple hexose and pentose sugars, using enzymes;
• fermentation of simple sugars into butanol, using a pure culture of Clostridium beijerinckii P206, anaerobic bacteria;
• butanol production.
The process has a unique feature: the three last stages are combined and performed in the same reactor. Qureshi’s team is now dealing with a patenting procedure for this process. Qureshi collaborates with Lars Angenent, an expert in ecology from the Washington University, and other experts from the USDA ARS with the aim of increasing profitability of hydrolysis stage. The idea is to replace the required enzymes (sometimes they are quite expensive) with a mixed microbial culture. In collaboration with Qureshi, Angenent is going to use the microorganisms collected from residues in sludge digestion tank and the microbes from sheep rumen for fermenting the preliminarily treated corn fibers into butyric acid. The findings will be delivered to Qureshi laboratory to be used for fermentation into butanol with Clostridium monoculture.
The collaboration is still at the stage of inception and funded through the USDA grant. Currently, Angenent’s team is focused on the optimization of butyric acid production by modifying such parameters as pH and temperature. As soon as they identify conditions facilitating the production of butyric acid in large quantities, Qureshi will undertake the lead in this effort.
7. Development of Butanol Production Technologies of Generation II
7.1. Open Joint Stock Company “Corporation ‘Biotechnologies’”
The JSC “Corporation ‘Biotechnologies’” is staking on the production of biobutanol of Generation II which is made of renewable non-food sources of raw materials – wood chips, straw and peat. This approach is not only resolving the issue of non-target use of agricultural products but also helps to overcome another challenge – the all-round accumulation of waste or littering of territories.
The JSC “Corporation ‘Biotechnologies’” has developed and is offering a technology of biobutanol production using cellulose-containing waste from agricultural and timber industry as fresh raw materials. This technology is absolutely unique and innovative. Actually, a fermentative butanol is obtained from cellulose-containing raw materials. This technology has been developed as an outcome of team efforts, as the prominent Russian experts working in this area were involved in its development and introduction. The technology was tested by a leading Russian research institute – the Open Joint stock Company “GosNIIsintezbelok.”
As regards cellulose, the key problem has a pure scientific nature: how to achieve its disintegration for enabling enzymes to make their job. The Russian invention is suggesting the following option for handling this issue: to grind cellulose to micron-size particles at the first stage of cellulose uncovering.
Many foreign companies have already invested millions of Dollars into the development of similar technologies. But all their attempts failed, especially at the industrial scale. As declared by OJSC “Corporation ‘Biotechnologies,’” their R&D efforts turned out to be more successful. The project has brought together specialists from the leading scientific schools: the Chemical Department of the Moscow State University; the Bauman Moscow State Technical University; the Moscow Engineering Physical Institute; and, the Bakh Institute of Biochemistry. A desired outcome has been achieved and received a positive peer review of the Russian Academy of Sciences.
Moreover, on September 09, 2008, for the first time in the world, biobutanol from wood was produced successfully with the use of this technology at the pilot line of the Open Joint Stock Company “East-Siberian Combine ‘Biotechnologies’” (VSKBT) located in Tulun, the Irkutsk Oblast. Three cars “Lada Kalina” fueled with the manufactured biobutanol (in different proportions with gasoline) made a successful run from Tulun to Tolyiatti under the joint project with the Open Joint Stock Company “Avtovaz.” Using biofuel (a mixture of gasoline and biobutanol) they covered the distance of 4 thousand km and reached the final destination without any trouble. The interim and final measurements demonstrated that hazardous environmental emissions from the automobile engines reduced dramatically.
VSKBT has been established at the base of the Open Joint Stock Company “Tulun Hydrolysis Plant.” It is a targeted biobutanol producing facility. According to the present estimations of the OJSC “Corporation ‘Biotechnologies,’” it is an optimal site for launching this technology both on a trial basis and at the industrial scale.
The Open Joint Stock Company “Tulun Hydrolysis Plant” is one of a few facilities in the domestic hydrolysis industry which have managed to survive.
It is possible to make a statement that a new industrial sector has already been conceived. In short-term, its development will require upgrades and launch of additional four similar facilities in Siberia. As estimated by the OJSC “Corporation ‘Biotechnologies’” and reflected in the worked out plans, the Russian biofuel industry will include up to 30 dedicated plants. The estimates look realistic taking into account a potential volume of product sales. The list of 30 facilities will cover both the old plants of hydrolysis industry and the distilleries (only 1/3 of their capacities is currently used).
It is worth noting that the use of capabilities of distilleries will help to resolve another Russian problem which is far from ecology, i.e. a “shady” component of the alcohol market.
It is not a secret that according to official statistics these capacities stand idle, but in reality many of them are used for making illegal alcohol “during the third work shift.”
The only nuance – Russia so far has no legislative framework for regulating issues related to biofuel production. However, this situation does not reduce heavy requirements of international companies for Russian biofuel. Probably, this requirement and the world market demand will facilitate the development of necessary legislative acts. And the latest Baikal Economic Forum has demonstrated that the demand for the product does exist even today. At this Forum, the OJSC “Corporation ‘Biotechnologies” concluded contracts on buiofuel supplies with the two world largest traders - Vertical and Noble Group.
Materials are prepared by analysts of Research Company Abercade