Abstract

Utilization of rice straw as renewable energy source has attracted increasing interest since the past two decades. However, rice straw has low heating value, low bulk density and significant amount of alkali and alkaline compounds. This makes it difficult to handle, transport and store efficiently hence limiting the commercial use of rice straw. These properties can be improved by pretreatment of the residue. This paper therefore explores the literature for information on some fundamental pretreatment techniques of rice straw to provide a basis understanding on how it could be improved as an attractive fuel for energy production. The pretreatment technologies discussed in this paper include sizing, torrefaction washing/ leaching, bailing and pelletizing. The aforementioned treatments improve both physical and chemical properties of rice straw by increasing the energy conversion and combustion efficiencies, reduce slag formation in the furnaces and grates etc thus minimizing the associated costs and logistics of handling, transport and storage which could encourage the commercial use of rice straw as a feedstock for heat and power production.

Key words: Rice straw, pretreatment, biomass, renewable energy, heating value, bulk density, conversion and combustion efficiency.