Mohr Davidow Announces Investment in ZeaChem, Developer of Hydrogenolysis Process for Cellulosic Ethanol
2 July 2007
|ZeaChem’s process combines the output of fermentation and gasification into a third process step, hydrogenolysis. Click to enlarge.|
Mohr Davidow Ventures (MDV), a leading Silicon Valley venture capital firm, announced today that it has invested in ZeaChem, the developer of a combined biochemical and thermochemical process for the production of ethanol from cellulosic biomass feedstocks. ZeaChem claims that its technology will produce 50% more ethanol per ton of feed than the current best-in-class technology.
The process combines the outputs of two traditional pathways (fermentation of sugars and gasification of biomass) into a third catalytically-driven step—hydrogenolysis—to produce ethanol. The process results in an energy output that is more than ten times greater than the total non-renewable energy input required to grow and deliver a biomass crop, according to the company.
ZeaChem is now building a biomass-to-ethanol pilot plant with this new process technology. Joining MDV in the $4 million round is Firelake Capital.
The biochemical processing step converts sugars in the cellulosic biomass into acetate via bacterial fermentation. The conversion can be either direct in a one-step fermentation process or via lactic acid to acetic acid in a 2-step process. (The production of lactic acid can provide an additional revenue source.) After fermentation, the acetic acid is extracted from the fermentation broth in an acid recovery stage and esterified.
The thermochemical processing step converts lignin and other non-fermentable materials in the cellulosic biomass into a syngas. The acetate ester from the fermentation pathway and the hydrogen from the syngas combine in a hydrogenolysis reaction to produce the ethanol.
Zeachem uses the thermochemical processing stage also to provide steam and power for the plant.
The Zeachem process thus can use all fractions of the plant—cellulose, hemicellulose, and lignin—producing much higher yield per ton of feedstock.
Because the yield is so much higher and because energy integration is tighter, the ZeaChem process is friendlier to the environment, according to the company. Ethanol produced by corn dry milling in the US has a net energy ratio of less than 1.6, meaning that fewer than 1.6 units of renewable energy are produced for each unit of fossil energy used in the production the crops and conversion of the crops into fuel ethanol. In contrast, ZeaChem claims a net energy ratio of 10-12.
The biochemical processing step can ferment any fermentable sugar, including simple sugars like those found in sugar cane juice, more complex sugars found in corn starch, and the mixed sugars commonly found in cellulosic hydrolyzates. Any material that isn’t readily fermented, such as lignin, can be processed via thermochemical means to produce hydrogen.
The Australian Sugar Research Institute has evaluated the ZeaChem process and confirmed the potential of the process to achieve significantly higher yields of ethanol from a variety of sugar process streams than conventional yeast fermentation process.
“Update on the ZeaChem technology for ethanol production from sugar process streams”; Edye, L. A., Lavarack, B. P., Bullock, G. E., Blinco, J. A. L., Hodgson, J. J., Hobson, P. A.; 2004 Conference of the Australian Society of Sugar Cane Technologists held at Brisbane, Queensland, Australia, 4-7 May 2004, 2004
“Reaction Paths in the Hydrogenolysis of Acetic Acid to Ethanol over Pd(111), Re(0001), and PdRe Alloys”; Pallassana V. and Neurock M.; Journal of Catalysis, Volume 209, Number 2, July 2002 , pp. 289-305(17)
Catalysis, James J. Spivey, Published 2004, Royal Society of Chemistry
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