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Jun 15, 2009 (Vol. 29, No. 12)

Alternative Feedstocks Boost Ethanol Production

Industry Increasingly Relies upon Cellulosic Biofuels to Meet Government Mandates

  • Cellulosic Ethanol Gains Ground

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    Coskata says that its three-step Flex Ethanol process, which combines gasification and fermentation, converts feedstocks into ethanol in an energy- and cost-efficient way.

    Wes Bolsen, CMO and head of government affairs at Coskata, discussed a recent Sandia National Labs and General Motors study demonstrating that 90 billion gallons of feedstock-flexible ethanol is possible in the U.S. without a significant change in current land use. The two major pathways used to produce cellulosic biofuels have traditionally involved the conversion of biomass using either biochemical (a combination of enzymatic hydrolysis and fermentation) or thermochemical (gasification and catalysis) methods, he explained.

    Bolsen described Coskata’s hybrid approach based on its Flex Ethanol™ technology, which combines gasification and fermentation in a thermo-biological pathway to produce fuel-grade ethanol that it contends can be cost-competitive with gasoline. The process is able to yield more than 100 gallons of ethanol per ton of dry biomass.

    Gasification of a carbon source “is commercially viable today,” Bolsen told the conference attendees, and Flex Ethanol technology can accommodate virtually any carbon-based feedstock, from traditional agricultural sources and construction waste to plastic, tires, and wood chips, converting the biomass to syngas, he said. “There are eight to ten different technologies we can use for front-end gasification.”

    Bolsen predicted that cellulosic ethanol production processes will become increasingly efficient at reducing carbon emissions. Coskata’s hybrid approach achieves as much as a 96% reduction in CO2, he noted. The next major issue in green fuel production will be water imbalance. Flex Ethanol technology has one of the lowest net water use numbers, according to Bolsen, compared to two to three gallons of water per gallon of gasoline produced, and two to four gallons of water per gallon of corn ethanol.

    Further, Bolsen reported that Coskata has licensed a variety of anaerobic bacterial strains capable of converting both CO and H2, and has patents pending for its bioreactor designs, which are scalable and capable of carrying out fermentation or converting syngas to ethanol at low-to-moderate pressures and low temperatures. The company is preparing for start-up of a semi-scale facility to demonstrate cost-effective cellulosic ethanol production.

    By 2012, Coskata envisions commercial production of 50–60 million gallons of ethanol per year, made by gasification of approximately 1,500 dry tons of biomass per day. With a projected production cost of $1–$1.50/gallon, Flex Ethanol will be cost-competitive with gasoline, claimed  Bolsen.

    Qteros is banking on its Q Microbe™ technology to make ethanol production from cellulose both cost-effective and commercially viable. Q Microbe is a lollipop-shaped microorganism that expresses a variety of plant-degrading enzymes, including cellulases, xylanases, and ethanol dehydrogenases, which are suitable for breaking down a range of feedstocks. Enzyme expression adapts to the feedstock available, explained Jef Sharp, evp at Qteros. If cellulose is the predominant feedstock, for example, cellulases are the main enzymes expressed by the microbe. Replacing cellulose with xylan results in the organisms producing more xylanase than cellulose.

    Q Microbe performs biomass breakdown and fermentation in a single step and can ferment both C5 and C6 sugars simultaneously, producing ethanol as the primary product. It hydrolyzes and liquefies biomass to yield a solution from which ethanol can be distilled.

    Qteros is working with the U.S. Department of Energy and the Department of Agriculture and is exploring scale-up with potential industrial partners. The company expects to begin operation of an internal pilot plant in 2009 and an external pilot plant in 2010, with a large-scale demonstration plant projected for 2011. Qteros plans to license Q Microbe technology to ethanol producers.

    Sharp predicted that the cost barrier for cellulosic ethanol production will be overcome within the next few months. This would open the market to ethanol that could be produced from the “420 million tons of biomass easily harvestable in the U.S.” Sharp also said that the ethanol generated from that biomass could replace at least half—about 45 billion gallons—of the oil the U.S. imports annually.

    While Q Microbe is not a GMO—it is a naturally occurring anaerobe that lives under the soil—the company is confident that the patents it is pursuing on the use of the microbe for ethanol production will yield a valuable intellectual property portfolio. Qteros has a genetic-engineering program in place to optimize the microbe for use in large-scale ethanol production.

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