Having enough storage space to maintain the minimum level of inventory (10 days) is vital to how much a facility can store on site. The quality of space and level of automation of the handling systems can greatly affect feedstock logistics. While some advocate that outdoor storage is adequate for biomass, this statement cannot be generalized as a rule of thumb, as

(b)

was earlier pointed out for the outdoor storage of corn cobs. Poorly stored feedstocks in outdoor storage will biodegrade more rapidly than indoor storage. Biodegradation of feed­stock could result in nutrient variability in the feedstock that will negatively affect conversion, handling challenges in conveying and processing, and potential fire and health hazards because of spontaneous combustion and inhalation of mold spores from deteriorating biomass. In general, woody feedstocks are more favorable to outdoor storage than herbaceous biomass. Figure 7.9a, b provides a good pictorial comparison of indoor stored bales of plant biomass and outdoor pile subject to deterioration by inclement weather.