Ramon Gonzalez and Syed Shams Yazdani have identified the metabolic processes and conditions that allow a known strain of Escherichia coli to convert glycerin into ethanol through an anaerobic fermentation process. Gonzalez is currently the William Akers assistant professor in chemical and biomolecular engineering at Rice University, and Yazdani is a postdoctoral research associate.
Reprinted with permission from Elsevier from Current Opinion in Biotechnology, Vol. 18, Issue 3, June 2007, Pages 213-219. Yazdani SS, Gonzalez R, Anaerobic fermentation of glycerol: a path to economic viability for the biofuels industry. doi:10.1016/j.copbio.2007.05.002
In a comparison of feedstock and operating costs, Gonzalez found that ethanol from glycerol is 39 cents cheaper to produce than ethanol from corn. Feedstock costs per gallon were 53 cents for corn, versus 30 cents for glycerol. Per gallon operating costs were 52 cents for corn and just 36 cents for glycerol (see table above). "The main reason for the difference in costs is that there is no preprocessing," Gonzalez says. In feedstock operations, the corn must be ground and cooked, and the sugar extracted. "It is a process that is both capital and process intensive," Gonzalez says. "You need to work all the way from the corn grain until you get sugar, and then you start fermentation." Meanwhile, glycerin doesn't require those steps because it comes preprocessed. This means no enzymes to buy and less equipment.
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The implications of this research are so promising that the process may be commercialized before cellulosic ethanol. Gonzalez partnered with Paul Campbell, who researches, develops and markets blends of microbes for industrial, agricultural and environmental markets, to form Glycos Biotechnologies Inc. The company, which was funded by Houston-based venture capital fund DFJ Mercury, expects to complete its pilot plant in early 2008. "Once we have the pilot running and working properly, [commercialization] is a matter of months," Gonzalez says, noting that the pilot plant is being designed to be one step away from a commercial-scale plant. Gonzalez couldn't say how big the pilot plant will be, but he says it would be capable of fermenting at least 10,000 liters.
Glycos Biotechnologies will not develop and sell the technology, Gonzalez says. Instead, the company plans to form partnerships with those already in the biodiesel, glycerin and ethanol industries, he says. The company's Houston location lends itself well to working with biodiesel producers, as there are several in the region.
Gonzalez says this process could be collocated with either an ethanol or biodiesel facility, and there are advantages to each. If collocated with a biodiesel plant, costs to transport glycerin would be saved. At least initially, this will be the most likely deployment of the company’s technology.
Glycerol is the principal component of glycerin, a clear, odorless, viscous liquid. It is found in animal fats, vegetable oils or petrochemical feedstocks, and is derived through soap production and the transesterification process, in which fatty acids and alcohol are mixed. Although glycerin has more than 1,000 uses, including many applications as an ingredient or processing aid in cosmetics, toiletries, personal care, drugs and food products, it is typically used in a highly refined and purified form. Refined glycerin is mostly pure glycerol, with the salt, methanol and free fatty acids removed.
The rapid growth of the biodiesel industry changed the glycerin market. In fact, it was cited as the reason that Dow Chemical Co., which produced synthetic glycerin, exited the glycerin production business in North America in 2006. "The increased supply of glycerin in North America due to biodiesel production, which caused prices to drop, was a factor in that decision," says Catherine Maxey, business public affairs director for Dow Chemical. "However, we continue to produce synthetic glycerin in Europe for sales into specialized markets such as pharmaceutical, personal care and food applications, among others, where high quality is the major requirement. The high purity at constant quality levels of Dow's synthetic glycerin presents distinct advantages over natural glycerin in these specialized end applications."
Maxey's point about glycerin quality is important when considering the market for the biodiesel by product. Biodiesel production yields unrefined glycerin. Biodiesel producers will usually then boil the glycerin to recover the methanol. This results in what is called crude glycerin, which is the form of glycerin most biodiesel producers sell. "[In most commercial applications], the quality of the glycerin must be high," says Gonzalez. "It can't be the nasty thing that comes out of biodiesel plants. If you use a feedstock that is not pure oil in biodiesel production, the glycerin is not very nice." Glycos's technology, however, can use the "nasty" glycerin—both unrefined and crude.
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