As studies continue to examine new value added uses for ethanol coproducts, it is important to have means to easily determine the feasibility of the processing steps involved. Many industries widely use computer simulation programs for this purpose, and for planning the use of resources and equipment capacities, and to determine processing costs. The objective of this project was to determine the sensitivity of 40 million gal/y corn-based ethanol plant model to changes in input material prices, product market prices, and various coproduct processing scenarios (i.e., oil extraction and drying of DDGS). The techno-economics of the base case ethanol plant were examined by factorially adjusting material and market costs, as well as adjusting the quantities of distillers wet grains (DWG), distillers dried grains with solubles (DDGS), and corn oil produced. The simulations verified that corn price has the greatest impact on the overall annual operating costs for the ethanol plant, and that the market price of ethanol has the greatest impact on annual revenues. The effect of coproduct processing on utility usage was also observed; oil extraction and drying of DDGS consumed substantially more energy and had higher capital costs than production of DWG alone. It was apparent that coproducts are an essential component to the sustainability of an ethanol plant in that: 1) they have continued marketability to the livestock industry, and 2) processing is not overly-expensive. This study has provided a basis for further exploration of the feasibility of new coproduct processing options, and illustrates the use of the model for determination of processing costs and revenues, as well as mass and energy balances. ABSTRACTAs studies continue to examine new value added uses for ethanol coproducts, it is important to have means to easily determine the feasibility of the processing steps involved. Many industries widely use computer simulation programs for this purpose, and for planning the use of resources and equipment capacities, and to determine processing costs. The objective of this project was to determine the sensitivity of 40 million gal/y corn-based ethanol plant model to changes in input material prices, product market prices, and various coproduct processing scenarios (i.e., oil extraction and drying of DDGS). The techno-economics of the base case ethanol plant were examined by factorially adjusting material and market costs, as well as adjusting the quantities of distillers wet grains (DWG), distillers dried grains with solubles (DDGS), and corn oil produced. The simulations verified that corn price has the greatest impact on the overall annual operating costs for the ethanol plant, and that the market price of ethanol has the greatest impact on annual revenues. The effect of coproduct processing on utility usage was also observed; oil extraction and drying of DDGS consumed substantially more energy and had higher capital costs than production of DWG alone. It was apparent that coproducts are an essential compon...

Cereal Chem. 90(1):70-79Wider exploration of ethanol coproduct uses is necessary as the ethanol industry continues to face challenges. Currently, process streams such as thin stillage and condensed distillers solubles (CDS) are processed into distillers dried grains with solubles and used as animal feeds, but other higher value opportunities may exist. The objective of this study was to identify chemical components and quantify physical properties of CDS and thin stillage. Protein, organic acid, and sugar profiles were determined. Zein protein was identified, and glycerol was determined to have a concentration of 18.8 g/L in thin stillage and 63.2 g/L in CDS. Physical properties including density, thermal conductivity, thermal diffusivity, and rheological behaviors were also examined. Thermal conductivity of thin stillage and CDS was approximately 0.54 and 0.45 W/m°C, respectively. Quantification of the physical properties and identification of the chemical constituents pave the way for exploration of new value-added uses for thin stillage and CDS.

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Coproducts, such as Distillers Dried Grains with Solubles (DDGS), produced during ethanol production are essential to the economic sustainability of each ethanol plant as they provide an additional source of revenue. DDGS is extensively used as animal feed, but has a relatively low market value compared to the biofuel. By fractioning DDGS into lighter and heavier fractions, the overall composition changes potentially increasing the value of the coproducts as they become more desirable to different markets. Earlier studies have examined fractionating DDGS using sieves and aspirators. This project examined the techno-economics of adding fractionation systems onto an existing 40 million gal/y ethanol plant. The model allowed for estimations of fixed capital costs, annual operating costs, annual revenues, and net profits, in order to determine the economic feasibility of adding three different fractionation systems. The first fractionation system consisted of a single sieve, and the retained material was passed through an aspirator. The second system was similar to the first but with a second sieve and aspirator. The third system added a third set of them. In addition to utilizing different fractionation systems, the scenarios examined the effects extracting corn oil and producing DWG in addition to DDGS. The fractionation systems examined in this study increased the capital costs associated with the facility, but did not greatly affect the overall annual operating costs. The net profits in the four most profitable scenarios were $0.349/gal EtOH/y (scenario 14), $0.350/gal EtOH/y (scenarios 6 and 10), and $0.351/gal EtOH/y (scenario 2).

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