Environmental performance and energy recoverable from stored rice straw bales in humid climate

The environmental performance and recoverable energy from stored rice straw bales with different storage methods and time for energy production were determined. Rice plants were harvested, baled, transported, and stored with different methods. The effects of different storage methods and time on physical and chemical properties and energy were also determined. The high heating values of dry rice straw bale did not differ significantly whether they were stored under the roof and outside with and without tarpaulin cover. For wet rice straw bales, these did not also differ significantly among storage methods in wet season. In dry season, the high heating values of wet rice straw bale were higher with storage outside than under the roof. After four months of storage rice straw bales that were stored under roof and outside with HDPE tarpaulin covers had comparable reduction in high heating values (5-7%) while those stored outside without cover had higher reduction in high heating values (15-17%) and higher solid waste generation. The cost of rice straw bales stored outside (USD 25-26/t) was comparable to those stored outside covered with HDPE tarpaulin (USD 25/t); however the former had the lowest net income (USD 559-580/t) than with a tarpaulin cover (USD 733-767/t). Indoor storage had comparable net income USD733-756/t with outdoor storage with tarpaulin cover. From harvesting of rice to storage of rice, straw bales had very high net energy (98.2%) with climate change potential of 706 kg CO sub 2 emission/t rice straw bale. N, P and C content significantly changed during storage. The stored rice straw bales for four months under the roof and outside with tarpaulin cover had comparable loss in high heating values (3-6%) irrespective of seasons and initial moisture content. Outside storage of rice straw bales without cover had higher loss of energy of about 15-17%.