Rice straw as a lignocellulosic resource: collection, processing, transportation, and environmental aspects

As open-field burning of rice straw is being phased out in California, rice growers and government agencies are looking for new rice straw uses, The amount of rice straw that may be available as a feedstock ranges from 1.0 to 1.4 million t yr(-1). Irrespective of its actual use as a source of raw material for liquid fuel, fiber, or power generation, a study of issues dealing with its harvest is needed. This paper reviews possible harvesting systems and provides an analysis of operating parameters such as straw moisture, density, storage, and optimal number of transport units. A case study of rice straw production in the Sacramento Valley was conducted, which illustrates that 550 t d(-1) of straw can be accessed at an estimated net delivered cost of about US $20it (dry), which is generally considered attractive for an ethanol feedstock. Gainfully utilizing this residue can ease the disposal problem facing agricultural operations in the State. Furthermore, the potential environmental benefits of diverting rice straw from open-field burning will be to significantly reduce criteria air pollutants such as VOC, SOx, NOx, and PM10, and also silica emissions, which are not specifically monitored but can be a health hazard. (C) 2000 Elsevier Science Ltd. All rights reserved.