Commercial alcohol production from natural sugar sources, namely the fermentation by common yeast of the sugars contained in fruits such as grapes, berries and apples, has been practiced for thousands of years. Fermentation of sugars derived from the starches of grains such as corn, barley and wheat, was developed later in history since another step, the conversion of the starches into C6 sugars, was required. The conversion of the starches is done by hydrolysis, which is simply the dissolution of starch compounds with water. The structural parts of plants are largely made up of polymers of sugar molecules. The most common polymer is cellulose, formed from C6 sugars, and a polymer called hemicellulose, primarily formed from C5 sugars. Since the mass of the structural parts of plants is much greater than the fruits or seeds, cellulose and hemicellulose are potentially significant sources of sugar for alcohol production. The conversion of cellulose and hemicellulose of plant stalks into their constituent sugars, however, is much more difficult than the same process for starches. Much research and development has focused on developing enzymes and acid treatment methods to free these sugars. Many companies, universities, and government organizations have made progress in the conversion of biomass to ethanol. Arkenol Inc. of Mission, CA, is developing a biomass to ethanol plant in California, based on a new strains of Zymonomas mobilis bacteria that can ferment five- and six-carbon sugars in biomass such as rice straw. Cayman Islands-based Agrol has developed a new technology using patented micro-organisms to convert materials such as household waste, paper pulp, forest waste, sawdust and straw into ethanol. Masada OxyNol LLC of Birmingham, AL, is building a plant in New York that will convert 230,000 tons/year of municipal solid waste (MSW) and 73,000 tons/year of sewage sludge into 9.5 million gallons/year of fuel grade ethanol. Ottawa-based Iogen Corp. is building a demonstration facility in Ottawa using enzyme technology to convert straw and other agricultural biomass to ethanol. Ethxx International, Toronto, Canada, has developed a process for converting biowaste into ethanol and other alcohols via syngas and Fischer-Tropsch routes. Another company that has been engaged in the development of biowaste-to-ethanol technology since 1992 is BC International (BCI), Dedham, MA. In 1995, the company announced that it would manufacture 20 plus million gallons of ethanol annually in the company's facility in Jennings, LA, using a technology that blends age-old sciences and leading-edge genetic engineering. The key to the technology is a proprietary microorganism that produces a high yield of ethanol from sugars derived from hydrolyzed organic waste (biomass), such as sugar cane residue (bagasse) and rice hulls. The microorganism works by breaking down the sugar compounds that are prevalent in biomass - sugars that current methods, which rely on fermentation, cannot utilize. The BCI process uses yeast and a genetically engineered organism to ferment all of the hydrolyzed sugars to alcohol. While the details of the new biomass to ethanol processes are considered to be proprietary, there have been a number of publications which generally describe the dilute acid route to biomass ethanol. A major contributor in this area has been the National Renewable Energy Laboratory (NREL) which has been working in this area for two decades and has built significant expertise. This new report from Chem Systems updates the production technology and economics for synthetic ethylene-based ethanol and fermentation ethanol (corn dry milling). For fermentation ethanol both industrial and fuel grade economics are presented. In addition, a speculative economic assessment of a biomass (corn stover) ethanol is presented. Nexant Chem Systems Merge Nexant, Inc., a leading provider of technology solutions and experienced-based technical and management consulting services to electric utilities, energy producers, oil and gas companies, governments, and energy end-users worldwide, has recently acquired Chem Systems. This acquisition, combining our services and products, allows us to span the full range of power, oil, gas, refining, petrochemicals and specialty chemicals sectors and provide our clients with a broader base of services in the energy and process industries. |
