Corn cobs were once viewed as an important biofuel feedstock early in U.S. history to heat houses, farm buildings, and small businesses. However, with the advent of combines, which left the cob in the field, the use of corn cobs as a biofuel declined dramatically. Corn cobs are used on a limited basis for industrial purposes in the United States for bedding, oil sorbents, polishing agents, and other uses. Now, corn cobs are reemerging as a potential biofuel feedstock for direct combustion, gasification, and cellulosic ethanol and appear to have numerous advantages over many competing feedstocks.
Corn cobs are dense and relatively uniform, and they have a high heat value, with low N and S contents, and can be collected during corn grain harvest. Harvesting cobs has little potential impact on soil residue, soil carbon, or the nutrient requirements of subsequent crops. Corn cobs appear to be a relatively sustainable, but relatively low-yielding, feedstock that can be used effectively in cellulosic ethanol, gasification, or co-firing applications. Two of the limiting issues are the need for a significant local resource base and the development of harvesting equipment, which is compatible with current corn-harvesting systems.