Butanol is increasingly being discussed as a possible gasoline blendstock, to be used as an alternative to ethanol in meeting government mandates for clean air standards and renewable fuel obligations. Butanol is a 4-carbon alcohol that can be produced by fermentation using the same or similar feedstocks as used in ethanol production, and this, along with some of its favorable properties, has led to considerable attention as the biofuel industry has developed in recent years.
Historically, beginning in the early decades of the 20th century, butanol was produced through the “acetone-butanol-ethanol” (ABE) fermentation process, which used different species of microorganisms of the genus Clostridium to convert feedstocks such as corn and molasses. Although first used in Britain during World War I to produce acetone, the ABE process later came to be used for the manufacture of butanol for the U.S. automobile industry, where it became an important chemical solvent as well as an ingredient for paints and surface coatings. Beginning in the 1950’s chemical production methods began to predominate, based on advances in petrochemical technology and the falling price of oil, and today, almost all the world’s butanol is manufactured using petrochemical processes.
Many observers feel that butanol overcomes many of the problems associated with the use of ethanol as a transportation fuel. Because butanol has a higher molecular weight than ethanol, it has lower vapor pressure, lower water solubility and most importantly a higher energy density. The low vapor pressure and lower water solubility mean that it can be more easily added to gasoline than ethanol. It is less corrosive than ethanol and so can be more easily transported in pipelines and used in vehicle engines in higher blend concentrations than ethanol without the need for extensive modifications; current standards in the U.S. and Europe allow a greater concentration of butanol in gasoline than is allowed for ethanol.
As noted above, biobutanol can be produced from the same organic feedstocks as ethanol, including conventional feedstocks like sugar cane, sugar beet or corn, and possibly also lignoceullulosic biomass from grasses, agricultural byproducts and other sources. Butanol can also be manufactured in facilities built for ethanol production. It has been asserted that some production technologies for biobutanol capture more biomass as fuel than is the case for fermentation of ethanol (that is, the butanol processes lose less of the organic carbon to CO2 than do ethanol fermentations). And at least one biobutanol producer believes that use of butanol as a fuel delivers greenhouse gas emission reductions that are at least as good as those seen with the use of ethanol. Butanol can also be used as a feedstock for biobased materials, including renewable hydrocarbons, chemicals and plastics.
Butanol has potential disadvantages as well. It is more toxic than ethanol and is reported to have a bad odor when hydrolyzed. Perhaps more importantly, while there are decades of experience in the use of ethanol in transportation fuels both as a blendstock and as a primary fuel, butanol has no such history. In spite of butanol’s long industrial usefulness as a solvent and for other purposes, it is far from clear whether it will be accepted by the transportation industry as a mainstream alternative fuel.
In view of the potential for butanol to serve as a renewable fuel in place of ethanol, there has been a resurgence of interest in developing improved fermentation approaches to the production of this chemical. In this entry of the blog, I’ll profile the companies that are known to be using advanced biotechnology to improve the fermentation processes that can be used to produce butanol or related molecules like isobutanol. It is hard to venture a guess at this time whether butanol will be successful in the marketplace either in its own right or as a replacement for ethanol. On the one hand, it is able to, and seems well-poised to, take advantage of the existing infrastructure for the production and distribution of ethanol, but the lack of a track record of its use as a transportation fuel will likely lead to a more difficult path to widespread market acceptance. Commercial production capacity for biobutanol seems to be coming online relatively rapidly (as I’ll discuss below), and the presence in the market of major players like DuPont and British Petroleum should guarantee that appropriate attention will be given to butanol’s potential as a transportation fuel. It is therefore possible to guardedly predict ultimate market success, but possibly only after a long “adoption” period as the market adjusts to this new role for butanol.
The following are the companies developing modified microorganisms for production of butanol, isobutanol, or related fuels.
- Arbor Fuels
- BUTALCO GmBH
- Bioenergy International*
- Butamax (DuPont/BP)
- Cobalt Biofuels
- Gevo, Inc.
- Green Biologics, Ltd.
- METabolic Explorer
- TetraVitae Bioscience
Several of these companies are also developing other fuels, and those marked with asterisks have been, or will be, profiled in other sections of the blog.
The following are brief profiles of companies that are developing engineered or modified microorganisms for the production of butanol, isobutanol or related fuels. These profiles have been adapted or excerpted from company websites and/or other publicly available information, and I don’t assume any liability for the accuracy, comprehensiveness or use of the information.
Arbor Fuel, Inc. is a technology company formed to utilize the power of biotechnology for the production of second generation alternative fuels, particularly butanol. Arbor is taking advantage of recent advancements in the understanding of microbiological processing of cellulose based plant material to engineer microbial strains and biological processes to convert cellulosic material into renewable bio-based fuel. The company’s strategy is to couple biotechnical approaches with advanced metabolic engineering technologies to create strains for cost effective generation of fuel from plant material. The company’s main area of focus is the development of microbial strains and processes to produce butanol from biomass. These patented microorganisms will use biomass as an environmentally sensitive and economically sensible feedstock for fuel production, and will be used in commercial biorefineries to generate long-term revenue either directly by Arbor Fuel or through partnerships with established commercial biofuel producers. Arbor Fuel has already developed a yeast strain that can grow on and digest cellulose and produce ethanol at greater than 90% of the theoretical maximum yield. The company is currently in the process of engineering new yeast strains that will produce butanol, maximizing on the latest in molecular biology technologies while utilizing well-understood processes and techniques.
BUTALCO GmbH, founded in August 2007 with headquarters in Zug, Switzerland, is developing new production processes for second generation biofuels and biochemicals based on lignocellulose. The company’s core technology based on genetically optimized yeasts enables increased yields in bioethanol production and the production of biobutanol. BUTALCO is developing a new process that would use C5/C6 sugars for fermentation of both ethanol and butanol, and is working together with its partners to develop an integrated lignocellulose-based bioethanol/biobutanol production process. This new process would cover the whole production chain including all steps from lignocellulose hydrolysis to downstream processing. BUTALCO has secured a first round of external financing from Volkswind GmbH based in Ganderkesee (Lower Saxony), Germany.
Butamax™ Advanced Biofuels was formed in 2009 by BP and DuPont to develop biobutanol, an advanced biofuel which the company expects will provide improved options for expanding energy supplies and accelerate the move to renewable transportation fuels. Butamax combines BP’s expertise in fuels technology, development and infrastructure with DuPont’s leading capabilities in biotechnology. The company’s near term focus is be to develop a technology program to produce biobutanol from many different types of feedstocks, including sugar and starch feedstocks and lignocellulosic feedstocks, at a price that is competitive with ethanol. In the future, Butamax expects to license the technology to produce biobutanol to other biofuel producers. The company will also work with fuel blenders and distributors globally to introduce biobutanol into the fuels market. The technology program will focus on how to produce biobutanol. Butamax intends to work closely with Kingston Research Limited to demonstrate production of biobutanol at a technology demonstration plant in the UK.
In October 2009, DuPont received a $9 million ARPA-E grant to develop Biomass Energy Production of bio-butanol from macroalgae (seaweed).
Cobalt Biofuels is developing innovative technologies to enable the next generation of biofuels. The company has assembled leaders in microbial physiology, strain improvement, fermentation and separation technologies, to make possible a new generation of fuels that burn cleaner, are more cost-effective, and have a smaller environmental impact than existing petrochemical-derived fuels.
Cobalt has developed proprietary, high-throughput processes for identifying and engineering the optimal microbial strains for converting a given plant material to alcohol fuels. This innovative technology makes it possible to process a range of feedstocks in the production of biobutanol and other high energy density biofuels. Cobalt’s current portfolio of technologies is aimed at advancing the commercial production of biobutanol from plant material. By optimizing fermentation productivity, yield, and titer, Cobalt hopes to make biobutanol a viable and economic transportation fuel.
Gevo Inc. is developing biological technologies to produce biobutanol for use as a gasoline blendstock. The company characterizes its approach as comprising three critical pieces of technology for the efficient and cost-effective production of advanced biofuels on a large scale. These are: (a) “Protein Engineering of Biocatalysts” to convert agricultural waste products into different types of renewable, alcohol-based, liquid fuels like butanol; (b) “Metabolic Engineering of Suitable Host Organism” to engineer suitable host organisms to efficiently produce fuel at increased yield and productivity sufficient for large-scale manufacture of commodity chemicals and fuels; (c) Process Engineering, a proprietary process technology to enhance productivity and lower product separation cost.
Gevo has partnered with Cargill to give Gevo exclusive rights to integrate Cargill’s proprietary microorganisms into its Integrated Fermentation Technology (GIFT®) process for the production of butanols from cellulosic sugars derived from biomass such as corn stover, switchgrass, forest residues, and other sustainable feedstocks. On November 13, 2009, Gevo announced that it has been awarded $1.8 million from the U.S. Departments of Energy and Agriculture’s Biomass R&D Initiative to help fund ongoing development of its yeast strain to produce biobutanol from cellulosic biomass, in this partnership with Cargill.
Gevo has also entered into a strategic alliance with ICM for the commercial development of the GIFT® process for the production of isobutanol and hydrocarbons from retrofitted ethanol plants. Gevo, has announced the start up of a biobutanol demonstration plant designed from retrofitting an existing demonstration scale ethanol plant. The company has claimed successful production of biobutanol at this 1 million gpy pilot plant in St. Joseph, Missouri., Gevo will be ICM’s exclusive technology partner for the production of butanols, pentanols and propanols.
Green Biologics Limited is a revenue-generating industrial biotech company based in Oxfordshire, U.K. aiming to become the world’s leading supplier of advanced fermentation technologies for conversion of biomass to renewable fuels and chemicals. One focus is on butanol, produced by microbial fermentation of sugars derived from biomass. GBL has isolated a cocktail of thermophilic (heat-loving) microorganisms for rapid enzymatic hydrolysis and release of fermentable sugars from biomass. Thermostable enzymes offer a faster, cleaner and more efficient process for biomass hydrolysis resulting in cost savings. GBL plans to integrate its patented hydrolysis technology with its proprietary biofuel fermentation process offering a reduction in both feedstock and manufacturing costs. GBL has developed superior butanol producing microbial strains using genetic engineering and will integrate these strains into a novel fermentation process. This technology advance should result in a step change in the economic viability of the fermentation.
METabolic Explorer, S.A., founded in 1999 and based in Clermont-Ferrand, France, is a green chemistry company that develops and patents innovative, fermentation-based industrial processes. The company’s processes are designed to use renewable resources to provide an alternative to petrochemicals for producing the bulk chemicals that are used in many everyday products. METabolic EXplorer is using its combined expertise in molecular biology, metabolic engineering and bioinformatics to design high-performance microorganisms that can transform plant-derived raw materials into an existing bulk chemical. METabolic EXplorer is developing a flexible and competitive fermentation process for butanol production. Butanol can be produced directly by fermenting starch, sugar, sugar cane juice, molasses and even hemicellulose.
TetraVitae Bioscience, Inc. is developing biobased chemicals, plastics, and fuels. The company’s proprietary technology and expertise in the fields of industrial fermentations, process engineering, microbiology, and cellulosic feedstocks are aimed at dramatically lowering the costs of production, providing the basis to compete with and replace petroleum-derived products.
TetraVitae’s focus is the production of biobutanol using a proprietary fermentation process and an enhanced microorganism platform. The company’s biobutanol technology has demonstrated significant improvements over conventional approaches and the company’s innovations have dramatically improved the efficiency of the historical microbial process that has been used for butanol production.
TetraVitae has patented a mutant strain of Clostridium beijerinckii that produces higher levels of butanol than wild-type strains and that is known for its stability, robustness, and responsiveness to genetic modification and improvement. This strain selectively produces high levels of butanol relative to any other known strain. An additional advantage of C. beijerinckii is the fact that the solvent-producing genes are located on the chromosome (rather than on the plasmid as is the case with some other species). This has the effect of making C. beijerinckii more genetically stable – an important requirement of a commercial deployment. Results from the current bench-scale integrated process demonstrated significant improvements in final solvent concentration, yield, and productivity over batch production methodologies.
TetraVitae is actively developing a microorganism platform that will have high yield on feedstock, high final product concentration (with reduced product inhibition), high selectivity for butanol production, and the ability to use low-cost feedstocks. These efforts will contribute to significant additional production cost reductions.
D. Glass Associates, Inc. is a consulting company specializing in several fields of biotechnology. David Glass, Ph.D. is a veteran of nearly thirty years in the biotech industry, with expertise in patents, technology licensing, industrial biotechnology regulatory affairs, and market and technology assessments. This blog provides back-up and expanded content to complement a presentation Dr. Glass made at the EUEC 2010 conference on February 2, 2010 entitled “Prospects for the Use of Genetic Engineering in Biofuel Production.” The slides from that presentation are available at www.slideshare.net/djglass99.