33 ddg produced in an ethanol plant can be used for

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33 DDG produced in an ethanol plant can be used for human consumption as long as the original ingredients (corn, enzymes, yeast) are GRAS (generally regarded as safe) and the processing plant is approved for food manufacture. Applications for DDG in the food industry would increase its value and demand, and would also change the design requirements for the process. Future directions for DDG price and demand remain uncertain. VII.1.2 Carbon Dioxide Fermentation of corn produces approximately equal amounts of CO 2 and ethanol. A few ethanol plants capture and sell this CO 2 , usually to an organization that specializes in cleaning and pressurizing it. For an ethanol producer to sell CO 2 , a user must be nearby and the amount of CO 2 generated must be great enough to justify the cost of the CO 2 recovery and purification equipment. VII.1.3 Corn Germ Current practice in most dry milling facilities today is not to degerm the corn but rather have the corn germ (and oil) be included in the DDG. Separation of the corn germ prior to fermentation should add to the profitability of the dry milling process. VII.2 The Future of Lignocellulose Process Co-Products VII.2.1 Electricity In the face of deregulation of the electric utility industry, relying on a high value for the excess electricity is difficult. For a plant to consider this a long-term revenue stream, optimizing the generation or sale of the power during peak consumption may be important. Storage batteries, storing boiler feed, banking steam, or employing turndown on the boiler or turbogenerator are all options for matching generation with demand and maximum value. Siting the plant must include negotiations with a power producer, with the hope of a long-term contract. Environmental regulations are different for power generators and there is a balance between ethanol or power generation as the primary function of the plant. The electricity value used in this analysis ($0.04 per kWh) comes from a study performed by an engineering firm for NREL in 1994. 34
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27 VII.2.2 Lignin Finding a way to make the lignin residue a higher-value co-product from the lignocellulose process is an important aspect of long-term commercial viability for the process. While it has value as a high/medium energy fuel, it is a new type of solids fuel and there is little demand for it outside of the plant boundaries, and the costs of drying it for transportation only subtract from its potential value. Gasification of the lignin could provide some help in converting it to a higher-value product with lower cost. Chemical or fuel production from lignin may be feasible; however the markets for potential products must be evaluated from both fledgling and mature ethanol industry views. VII.2.3 Other Co-Products Cell matter, furfural, and acetic acid have been identified as potential co-products.
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