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Bio-energy is obtained from biomass (any plant or animal matter). Bio-energy in the form of heat or electricity can be produced by using biomass directly as a fuel or by converting it to biogas or liquid bio-fuel. The main source of biomass include:
- Industrial and agricultural wastes and residues such as sugar cane waste (bagasse), wood waste from forestry operations,and residues from other short rotation crops such as straw and husks.
- Organic waste from animal husbandry.
- Energy crops, such as sugar cane,corn and trees grown in short rotation plantation.
The main processes of utilizing these biomass sources include:
- Direct combustion, usually of solids,in boilers or furnaces.
- Gasification via physical or chemical conversion processes to a secondary gaseous fuel, followed by combustion in a engine or turbine.
- Biological conversion via bacterial anaerobic digestion to methanol rich biogas for use as a gaseous fuel;
- Chemical or biochemical conversion to produce methanol, ethanol or other liquid fuels.
A bio energy project can often be designed to co-generate both heat and electricity. Such project may also create a cost-effective solution to the disposal of agriculture or industrial wastes that may otherwise become potential environment problems, for example UNIDO's sisal waste project in Tanzania.
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