|JANDA KONIECZNY, GERHARD|
Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2011
Publication Date: 4/5/2011
Citation: Nghiem, N.P., Ramirez, E., Mcaloon, A.J., Yee, W.C., Johnston, Hicks, K.B. 2011. Economic analysis of fuel ethanol production from winter hulled barley by the EDGE (Enhanced Dry Grind Enzymatic) process. Bioresource Technology. 102:6696-6701.
Interpretive Summary: We previously developed a new process that uses winter barley, rather than the more common feedstock, corn, to make fuel ethanol. Use of corn has been criticized because it is a food crop whereas winter barley is grown on fallow land and does not in any way compete with food production. The new process requires the use of some expensive enzymes, natural catalysts that are not used in the corn to ethanol process. Ethanol plant builders and operators are reluctant to use the new enzymes because their cost-benefit ratio is unknown. Therefore, we created the first computer process and cost model for the barley to ethanol process. With this model, we were able to show that under almost all market conditions, the use of beta glucosidase, an expensive enzyme, resulted in lower-cost production of the fuel ethanol. Only when barley prices were extremely low and when enzymes prices were extremely high, did it not pay to use the enzymes. This model and its results can be used by scientists, engineers, and technicians in the ethanol research and production areas to determine the most economic use of these processes and enzymes. Winter barley producers will benefit because of increased markets for this crop. Ethanol producers will benefit by lowering the cost of production and having alternative feedstocks to corn. The environment will benefit by increased production of winter barley, which acts as a winter cover crop, reducing erosion and nutrient loss into sensitive waterways, like the Chesapeake Bay.
Technical Abstract: A cost model was developed for fuel ethanol production from barley based on the EDGE (Enhanced Dry Grind Enzymatic) process (Nghiem, et al., 2008). In this process, in addition to beta-glucanases, which is added to reduce the viscosity of the barley mash for efficient mixing, another enzyme, beta-glucosidase, is also added to completely hydrolyze the glucose oligomers obtained during the hydrolysis of beta-glucans in barley grains by beta-glucanases to the fermentable sugar glucose. The model allows the determination of capital costs, operating costs, and ethanol production cost for a plant producing 40 million gallons of denatured fuel ethanol annually. The inputs to the model include barley cost, enzyme cost allowances, and potential selling price of the distillers dried grains with solubles (DDGS) co-product. A sensitivity study was also performed to examine the effects of alpha-glucosidase and barley costs on the final ethanol production cost. The results of this study clearly demonstrate the economic benefit of adding beta-glucosidase. Lower ethanol production cost was obtained compared to that obtained without beta-glucosidase addition in all cases except one where highest beta-glucosidase cost allowance and lowest barley cost were used. The economical benefits of adding beta-glucosidase significantly increase with decreases in beta-glucosidase cost and increases in barley cost.