Denatured ethanol for October delivery fell 8.9 cents to $1.854 a gallon on the Chicago Board of Trade. According to Bloomberg News, this was due to speculation the corn harvest will lower the costs to make the biofuel and boost supply. The price difference between the cost of the grain and a gallon of ethanol, reached the highest level this year. Corn for December delivery slumped 6.5 cents, or 1.4 percent, to $4.6875 a bushel in Chicago.