Conversion of Rice Husk and Nutshells into Gaseous, Liquid, and Solid Biofuels

Nowadays, biomass is considered as a main renewable energy source with a high contribution value to the worldwide energetics. In general, biomass is represented by solid waste materials from plant and animal farming, horticulture, food processing, etc. All these wastes are nonedible and cannot be used as food or feed. Among the agricultural solid wastes, rice husk and nutshells are of a special attention due to their high production. In this chapter, the main approaches and concepts of the rice husk and nutshells transformation into valuable gaseous, liquid, and solid products are overviewed. In some cases, the initial biomass should be pretreated to enhance the efficiency of its further conversion. The transformation processes can be classified onto direct combustion (solid fuel), pyrolysis and hydrothermal methods (solid and liquid fuels) and gasification (gaseous fuel). The commonly used fixed-bed and fluidized-bed reactors including catalytic ones, auger reactor, and plasma gasifiers are widely applied.