We are harvesting whole corn as it's great for weaning calves. But collecting the cobs for use in a furnace frees up the alcohol for other uses - like fuel for vehicles.
Alcohol Fuel Manual Ch17-18:
"Each 70 pounds of unshelled corn will yield a bushel (56 pounds) of shelled corn and 14 pounds of corn cobbs. The shelled corn, when processed, will yield about 2.5 to 2.7 gallons of alcohol. The corn cobbs, when dried and burned in a boiler, will produce 91,000 Btu which is enough to completely fuel the cooking and distillation operations. "