This paper analyzes the Illinois State Variety Test results for total and extractable starch content in 708 samples of 401 commercial varieties of corn. It is shown that the normally distributed extractable starch content has the mean of 66.2% and the standard deviation of 1.13%. The corresponding maximum theoretical yield of ethanol is 0.364 kg EtOH/kg dry corn, and the standard deviation is 0.007. In the ethanol industry units, this yield translates to 2.64 gal EtOH/nominal wet bushel, and the standard deviation is 0.05 gal/bu.The U.S. ethanol industry consistently has inflated its ethanol yields by counting 5 volume percent of # 14 gasoline denaturant (8% of energy content) as ethanol. Also, imports from Brazil and higher alcohols seem to have been counted as U.S. ethanol. The usually accepted USDA estimate of mean ethanol yield in the U.S., 2.682 gal EtOH/bu, is one standard deviation above the rigorous statistical estimate in this paper.
[1]
T. Patzek.
Thermodynamics of the Corn-Ethanol Biofuel Cycle
,
2004
.
[2]
E. J. Fox,et al.
A 100-g Laboratory Corn Wet-Milling Procedure
,
1996
.
[3]
Ian W. M. Smith,et al.
Supporting Online Material
,
2004
.
[4]
Andrew D. Jones,et al.
Supporting Online Material for: Ethanol Can Contribute To Energy and Environmental Goals
,
2006
.
[5]
Michael Q. Wang,et al.
The Energy Balance of Corn Ethanol: An Update
,
2002
.
[6]
David Morris,et al.
The Carbohydrate Economy, Biofuels and the Net Energy Debate
,
2005
.