Selecting technology when off by a factor of 50 is not going to provide the anticipated results.
For what it's worth, I think you will find that the average acre of corn in the US will now produce about 437 gallons of ethanol. The 138 bushel per acre yield and the 2.7 gallon per bushel distillation rate are based upon 1996 - 2005 averages. Both the yield and the efficiency of distillation are increasing at a pretty good clip.