Bioenergy Production: Special Emphasis on Rice Husks Usage in India - Implementing Environmental and Resource Management - page 15

3 Bioenergy Production: Special Emphasis on
Rice Husks Usage in India
Satyanarayana Narra
Chair of Mineral Processing, Brandenburg University of Technology (BTU),
Cottbus, Germany
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 account-
ing for about 40% of food grain production and over 30% of its cropped area. In-
dia'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 in-
dustries involves handling and transportation. Rice husk has a very low bulk den-
sity (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 microorgan-
isms, 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 en-
ergy is available at relatively high efficiencies. Under the best operating condi-
tions, 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 neu-
tral fuel. The CO 2 released is much less as compared to the amount of CO 2 seques-
trated during the growth of the rice. Thus, the net amount of CO 2 added to the at-
mosphere 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 poten-
tial 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-