Abstract: A method for storing cellulosic feedstock materials, particularly corn cobs, to facilitate the production of ethanol therefrom is effective to store feedstocks having a moisture content between about 20% and 50%. The method is initiated with the piling of the feedstock into a smooth, substantially rounded pile. The cellulosic biomass desirably has a substantially uniform average moisture content throughout the pile. High and low moisture materials can be mixed uniformly before being accumulated in the pile. The incorporation of oxygen into the pile is controlled by packing the pile in accordance with the moisture content and by covering the pile with an impermeable material. The pile of cellulosic feedstock achieves a temperature from 150 to 170° F., which depletes oxygen and creates acetic acid to facilitate subsequent processing of the feedstock into ethanol.