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Title: Novel technologies for enhanced production of ethanol: impact of high productivity on process economics

item AZAM, M - Rajendra Institute
item EZEJI, T - Ohio Agricultural Research & Development Center
item Qureshi, Nasib

Submitted to: European Chemical Bulletin
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2014
Publication Date: 8/29/2014
Publication URL:
Citation: Azam, M.M., Ezeji, T.C., Qureshi, N. 2014. Novel technologies for enhanced production of ethanol: impact of high productivity on process economics. European Chemical Bulletin. 3(9):904-910.

Interpretive Summary: To achieve sustainable and economical delivery of biofuels such as ethanol it is essential to produce them from renewable resources such as corn, corn stover, rice straw, or other agricultural residues. In addition to the use of the above agricultural products as feedstocks, price of ethanol is affected by fermentation productivity and economical recovery. In these studies, we improved ethanol productivity and concentration in the fermentation mixture by a factor of 4-5. As a result of these improvements it was projected that ethanol could be produced for $0.91/kg ($2.83/gal) from corn. It was also projected that further improvement in reactor or fermentation productivity could reduce these prices to $0.59/kg to $0.70/kg of ethanol. These production prices correspond to $1.83/gal to $2.18/gal of ethanol. Production of ethanol in this price range would tremendously benefit the automobile industry, the consumer, and the farmers. Use of agricultural residues is expected (corn stover, rice straw, wheat straw etc.) to reduce these prices further.

Technical Abstract: In these studies Saccharomyces cerevisiae NRRL Y-566 was used to produce ethanol from a concentrated glucose (250-300 gL-1) solution. When fermentation media were supplemented with CaCO3 and CaCl2, ethanol concentrations, yield, and productivities were improved significantly. In control batch fermentation, the culture was able to produce 20.87 gL-1 ethanol with a productivity of 0.25 gL-1h-1 when using 100 gL-1 sugar solution in feed. When supplemented with a solution of 0.40 gL-1 CaCl2, ethanol concentration, yield, and productivity were improved to 90.0 gL-1, 0.48, and 1.25 gL-1h-1 (500% increase), respectively. The effect of CaCO3 supplementation was not as pronounced as that of CaCl2. Using these parameters, the process economics for production of ethanol was performed and it was projected that supplementation with 0.40 gL-1 CaCl2 would result in the production of ethanol for $0.91 kg-1. It was also projected that improving productivity to 37.5 gL-1h-1 using cell recycle and supplementation with CaCl2 would result in the production of ethanol for $0.70 kg-1 employing S. cerevisiae NRRL Y-566. Using Z. mobilis in membrane cell recycle reactors and application of CaCl2 can result in achieving high productivities (500-600 gL-1h-1) and reduction in ethanol production price to $0.59 kg-1.