Ethanol yield calculation method - "An unaccounted factor" responsible for yield variations

Bioethanol is considered as a promising alternative to petroleum as a transportation fuel. The ethanol production from corn involves converting starch to glucose, followed by fermenting glucose to ethanol by yeast. The ethanol concentration at the end of fermentation can be determined using chemical assays or chromatography techniques. However, calculations of ethanol yields (L/kg corn) is challenging because of difficulty in measuring exact liquid volume at the end of fermentation. Various theoretical and experimental approaches have been used in literature to calculate the ethanol yields. The objective of this work was to demonstrate the variation in the ethanol yield calculated using different methods, and need to identify a comprehensive and reliable approach. This paper discusses various methods reported in the literature and also present a new theoretical method to calculate ethanol yields. Ethanol yields obtained from the new method were similar to those obtained using comprehensive experimental approaches.