Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 21, 2002
Publication Date: N/A
Technical Abstract: Fuel ethanol production in the USA has grown from an insignificant amount in the late 1970's to a record of 1.85 billion gallons in 2001. More than 95% of this fuel ethanol is produced by fermenting glucose derived from corn starch. Various lignocellulosic agricultural residues such as corn fiber, corn stover, rice straw, wheat straw, and sugarcane bagasse and energy crops such as switchgrass are available as low-cost feedstock for production of biofuels and value-added chemicals by fermentation. The process of converting these materials to ethanol includes feedstock pretreatment, enzymatic saccharification, fermentation, and product recovery. At present, no commercial process exists in the USA for such manufacturing, although efforts are underway. Success depends primarily on the development of an effective pretreatment process for rapid enzyme accessibility while minimizing the formation of fermentation inhibitors, as well as highly efficient enzymes for conversion of pretreated substrates to simple sugars. Pretreatment options include dilute acid, steam explosion, ammonia fiber explosion (AFEX), alkali, and alkaline peroxide treatment. Currently, the cost of cellulase enzymes is 50 cents per gallon of ethanol produced from pretreated corn fiber substrate. Research emphasis is being directed towards lowering the cellulase enzyme cost by a factor of 10. A number of recombinant microorganisms have been developed at various laboratories in the USA to ferment mixed sugar substrates to ethanol. In this presentation, the current state of technology research and process development in the United States, and efforts to bring this technology into the market place will be reviewed. Recent research progress dealing with the production of other value-added chemicals such as xylitol, mannitol, arabitol, 2,3-butanediol, and lactic acid will be described.