Improvements in ethanol’s energy consumption have continued since large- scale commercial production began in the 1970s. The process has become more efficient at using the starch in the corn kernel, approaching the theo- retical limit of about gallons of ethanol per bushel. Energy for conver- sion has fallen from as high as 70,000 Btu’s per gallon in the late 1970s (Wang, August 1999) to 40,000 Btu’s or less for modern dry mills and to 40,000-50,000 Btu’s for wet mills. Modern energy-saving technology and process optimization account for the improvement
