Bio-energy includes those processes where biological forms of matter, such as plants, vegetables etc. provide the basis for energy or its conversion from one form to another form of energy. The widest use of bio-energy is in the traditional way where, wood plants and agricultural matter are directly burnt to provide heat.
Vegetable biomass is a new name for plant organic matter, wherein solar energy is trapped and stored through the process of photosynthesis in which CO2 and water are transformed and form energy rich organic compounds. Biomass covers a wide range of materials, encompassing all kinds of animal, organic and synthetic wastes and a special variety of vegetation-wild grass, shrubs and some plants and trees, especially cultivated to derive energy and useful by-products and this biotechnology is one of the oldest manufacturing activities, having started over since man learnt to produce bread, wine, bear and cheese.
However, only recently the process is well understood and mankind has started to move in the right direction to make better use of this revolutionary technology.The major components of biomass are mainly carbohydrates-sugar, starches and cellulose- with variable nitrogen and phosphorus contents. Animals, organic and synthetic wastes cover the balance components. There are three basic systems for conversion of biomass into energy resources.
(1) Combustion Pyrolysis:
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Chemical decomposition through high temperature (up to 50°C) in partial or total absence of air to produce fuel gas, oil (methanol) and charcoal.
(2) Biogasification:
Anaerobic digestion of biomass to produce combustible gas (biogas) comprising of methane, hydrogen etc.
(3) Fermentation:
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Conversion of sugar and starch into alcohol to produce ethanol and solid residual fuel.
Biogas has a wide range of applications, which include cooking, running engines and generation of electricity through cogeneration of gas turbines.
The slurry produced in the process of biogas generation is enriched manure. Ethanol has a competitive market for food and fuel applications. The potential of biomass in India is estimated at 1250 MMTPA which is about one-eightieth (1/80) of the global total. Energy available from such a massive biomass is equivalent to about 300 MMT of oil.
Apart from energy demand aspects, there is an urgent need to cultivate high density and short-rotation species of deciduous trees and shrubs to crub the violent erosion of top soil with uncontrolled and reckless deforestation in many parts of the country. Non-agricultural deforested and marginal lands may, thus, form an alternative land resource for cultivation of this multi-purpose biomass so as to avoid competition with food crops. These are immense benefits with such planned biomass cultivation. It offers clean fuel/ energy and maintains an unpolluted environment, reduces carbon dioxide content in the atmosphere improves soil and water retention, capacity of the marginal and threatened lands.
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Wasteland and other non-agricultural land can be utilized for planting fast growing varieties of trees. The wood harvested each year can be converted by direct combustion or gasification to power and charcoal. It has been estimated that about 1000 hectares can provide about 3 MW of power, besides providing fuel wood or charcoal which can support the energy needs of a population of 125-150 families.
In India, even if one fifth of the estimated 80 million hectares barren and wasteland can be covered by such a programme, a generation capacity of about 48000 MW can be created, which is considerably more than the entire installed power capacity in the country today from all thermal, hydro and nuclear sources. This would also provide fuel wood and charcoal to meet the cooking needs of rural poor, provide green biomass covers in arid zones and raise rural income. The investment cost for such projects could be only about Rs. 14,000 per KW. The
EPP programme has already been taken up by Department of Non-Conventional Energy Sources. Under this programme, plantations of several quick growing species have been set up at various places of the country. This would not only yield fuel for power, but also help in providing timbers, restore fertility of the land, halt deforestation, prevent soil erosion, reduce flooding and improve microclimate of the environment.