Outdoor field storage of round-baled rice straw to suppress the cost of producing bio-ethanol from rice straw was investigated. Harvested rice straw was dried, collected, compressed and packed into round bales (rolls) by a round baler. Usually, the rolls are stored in a warehouse, or outdoors wrapped in a film coat. However, these storage costs push up the price of the bio-ethanol produced and reduce energy efficiency. To avoid this, outdoor field storage of rice straw rolls with or without film wrapping (wrapped rolls or non-wrapped rolls) was investigated in this study. The rolls were stored for about 9 months, from 19 December 2008 to 9 September 2009, taking into consideration the supply of rice straw for demonstrating a bio-ethanol pilot plant throughout the year. No significant increase of temperature in each roll was observed during the storage term, even though an increase was reported in previous studies. However, the straw should be stocked for other seasons, and it is important to grasp any problems during the storage period. In this study, no significant change was observed in the non-wrapped rolls throughout the term, suggesting that non-film wrapping round-baled rice straw can be stored in fields outdoors.
