August 12, 2006

Celunol's "wet" biomass conversion process

There are "wet" and "thermal" systems for converting biomass into cellulosic ethanol. Two companies' technologies are being combined to build one wet demonstration facility in Jennings, Louisiana. The final configuration involves pretreatment of cellulosic feedstock using an enzymatic hydrolysis system developed by SunOpta. The conversion of the glucose to ethanol uses a bacterial fermentation process developed by Celunol Corp.

By contrast, "thermal" systems typically use high heat to break down the chemical bonds of the feedstock. Gasification produce syngas that is fermented into ethanol in bioreactors.

Here are excerpts from the announcement as reported by Green Car Congress...

SunOpta Announces System Sale to Celunol for Cellulosic Ethanol Demonstration System

SunOpta Inc. has sold a continuous process system, including SunOpta’s patented and proprietary biomass conversion technology, to Celunol (formerly BC International) for Celunol’s cellulosic ethanol commercial demonstration facility in Jennings, Louisiana

The SunOpta Bioprocess Group has been designing, building, and optimizing biomass conversion plants for over thirty years. End products include cellulosic ethanol, cellulosic butanol, xylitol, and dietary fibre for human consumption. Raw materials include wheat straw, corn stover, grasses, oat hulls, wood chips, and sugarcane bagasse.

Celunol Corp. ( is a privately held company headquartered in Dedham, Massachusetts moving rapidly to commercialize its proprietary technology for producing ethanol from a wide array of cellulosic biomass feedstocks--including bagasse, agricultural waste, wood products and dedicated energy crops. The company is currently completing an expansion of its existing pilot facility and is moving forward to construct a demonstration plant based on its technology later this year. Celunol aspires to develop and build a portfolio of ethanol facilities in the U.S. and abroad. Shareholders in the company include Braemar Energy Ventures, Charles River Ventures, Khosla Ventures, and Rho Capital Partners.

Carlos Riva, President and Chief Executive Officer of Celunol, noted the advantages of acquiring the SunOpta technology, "Incorporating SunOpta's biomass pretreatment system into our proprietary process will further enhance the operating efficiencies of our Jennings facility, and will advance the rapid commercialization of Celunol's cellulosic ethanol technology."

The key element of Celunol’s technology is genetically engineered Escherichia coli bacteria that can ferment both C6 (hexose) and C5 (pentose) sugars present in cellulosic biomass. (Numerous research efforts around the world are tackling the same problem using different modified organisms such as Zymomonas, Saccharomyces, Lactobacillus, xylose-assimilating yeasts and Clostridium in addition to E. coli.)

E. coli ferments a range of sugars: arabinose, glucose, mannose and xylose. However, wild strains produce a range of fermentation products, but little ethanol. A recombinant E. coli for converting pentose sugars to ethanol was first developed in 1987.

Problems with the bacteria include the pH range for fermentation and the need to withstand the harsh production environment.

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