Environmental Engineering Reference
In-Depth Information
30
Sunflower
Sanjeev K. Sharma
Unichem Laboratories Ltd.
Krishan L. Kalra and Gurvinder S. Kocher
Punjab Agricultural University
contents
30.1 Introduction ........................................................................................................................ 717
30.2 Lignocellulosic Biomass ..................................................................................................... 718
30.3 Lignocellulosic Biomass Conversion .................................................................................. 719
30.4 Pretreatment ........................................................................................................................ 719
30.4.1 Mechanical Pretreatment/Milling ........................................................................ 720
30.4.2 Physicochemical Pretreatment ............................................................................. 720
30.5 Cellulase Production ........................................................................................................... 721
30.5.1 Cellulolytic Microorganisms ................................................................................ 722
30.5.2 The Cellulase Complex ........................................................................................ 722
30.5.3 Cellulase Production ............................................................................................. 722
30.6 Saccharification .................................................................................................................. 725
30.6.1 Acid Saccharification ............................................................................................ 725
30.6.2 Enzymatic Saccharification .................................................................................. 726
30.6.3 Simultaneous Saccharification and Fermentation ................................................ 727
30.7 Ethanol Fermentation ......................................................................................................... 727
30.7.1 Ethanol Production ............................................................................................... 728
30.7.2 Ethanol Recovery ................................................................................................. 729
30.8 Conclusions ......................................................................................................................... 729
References ...................................................................................................................................... 730
30.1 IntroductIon
Limited stocks and exorbitant prices of petroleum products create the need of finding some suitable
alternative fuels or fuel supplements (Wyman 1996; Lynd et al. 2005). Ethanol has especially
attracted interest as an alternative transportation fuel for two reasons: (1) the oil crisis in the mid-
1970s stressed the dependence on the supply of petroleum, which can be reduced by the use of
alternative fuels such as ethanol from renewable resources; and (2) if the ethanol production process
only uses energy from renewable energy sources, no net carbon dioxide is added to the atmosphere,
making ethanol an environmentally safe fuel (Kheshgi et al. 2000).
Ethanol can be blended approximately 10-15% with gasoline, as it is now in the United States,
or it can be used as 22-25% blends, as in Brazil. These blends realize three major benefits. First,
the gasoline consumption is reduced, thereby lowering oil imports. Second, ethanol increases the
octane number of the gasoline, thereby improving the engine performance. Third, ethanol provides
oxygen for the fuel, resulting in better combustion. Ethanol can also be used as a nearly pure or
“neat” fuel. Hydrous ethanol containing approximately 95% ethanol and 5% water is used as a fuel
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