Bioenergy Production: Special Emphasis on Rice Husks Usage in India
Rice is a staple food crop. Its annual production in India and the world is about 90 and 400 Million Tons (MT) respectively. Rice is a major cereal in India accounting for about 40% of food grain production and over 30% of its cropped area. India’s share
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3.1 Introduction Rice is a staple food crop. Its annual production in India and the world is about 90 and 400 Million Tons (MT) respectively. Rice is a major cereal in India accounting for about 40% of food grain production and over 30% of its cropped area. India’s share in world rice production is about 22% (Baruah and Jain 1998). Rice is the edible form of paddy and in the process of conversion from paddy, rice husk and rice bran are generated as by-products. The rice husk is generally used as a fuel the form of bricks, furfural and many others. The use of husk in industries involves handling and transportation. Rice husk has a very low bulk density (112-144 kg/m-3), which increases the handling and transportation costs. In the past, rice husk was mostly dumped as waste causing a waste disposal problem for the mills (Beagle 1981). Also, when rice husk is fermented by microorganisms, methane is emitted contributing to global warming problem (Bhattacharya et al. 1999). Rice husk is a fine and light particle and can cause breathing problems (Beagle 1981). Hence, rice mill owners must find the proper way to deal with this waste. The onsite usage of rice husk would reduce the handling and transportation costs. Technology for the conversion of rice husk into electricity and thermal energy is available at relatively high efficiencies. Under the best operating conditions, an efficiency of up to 65% can be achieved. The usage of rice husk would also reduce the greenhouse gas emissions as rice husk is considered as carbon neutral fuel. The CO2 released is much less as compared to the amount of CO2 sequestrated during the growth of the rice. Thus, the net amount of CO2 added to the atmosphere during energy production through the use of rice husk over the entire life cycle is nearly zero (Mann and Spath 1997; Hall and Scrase 1998). The availability of rice husk depends on the paddy production. The availability of this material is only 7 months (June to December) in a year. Total energy potential would depend upon the calorific value (12.1-15.2 MJ/kg) (Beagle 1981). The potential of rice husk depends on the quality (different varieties of rice husk) and quantity available. Variations in rice husk availability are dependent on the geo-
M. Schmidt et al. (eds.), Implementing Environmental and Resource Management, DOI 10.1007/978-3-540-77568-3_3, © Springer-Verlag Berlin Heidelberg 2011
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Satyanarayana Narra
graphical distribution, seasonal distribution and also on the capacity of rice mills. The basic idea of rice husk as an energy source relates to its thermo-chemical conversion. Gasification of rice husk to produce a gas has a high potential in India. The produced gas can be used to generate electricity (15% efficiency) using an internal combustion engines. Another usage of rice husk would be the generation of thermal energy (55% efficiency). However it is expected that the efficiencies of over 40% could be achieved for electricity generation through rice husk gasification. Cogeneration of electrical and thermal ene
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