Hay producers have long been aware of the risks of storing this combustible material. Images of barn fires caused by tight stacks of high-moisture bales are always in the back of their minds. So, as cellulosic biofuel demonstration projects were conducted over the past decade, great care was taken to develop biomass storage procedures to avoid spontaneous combustion. Additionally, this effort was highly successful because, to our knowledge, no fires in herbaceous feedstocks (such as corn stover or switchgrass) have been attributed to spontaneous combustion. However, fire remains a significant risk for facilities that handle and store biomass. Nearly every company with large volumes of corn stover or switchgrass in storage has experienced a major fire. Lastly, these fires are especially troubling because the most common ignition sources?lightning and arson?are essentially unavoidable.