This study, now nearly 12 years old, was conducted by the United States Department of Agriculture (July 1995) by Hosein Shapouri, James A. Duffield and Michael S. Graboski:
ABSTRACTFacts rarely get in the way of those with "old world" mentality. During the past 12 years, the ethanol industry has made technological and engineering advancements to make ethanol a clean, renewable domestic fuel.
Studies conducted since the late 1970's have estimated the net energy value of corn ethanol. However, variations in data and assumptions used among the studies have resulted in a wide range of estimates. This study identifies the factors causing this wide variation and develops a more consistent estimate. We conclude that the net energy value of corn ethanol has become positive in recent years due to technological advances in ethanol conversion and increased efficiency in farm production. We show that corn ethanol is energy efficient as indicated by an energy ratio of 1.24.
Source: Governor's Ethanol Coalition