Biogas Combustion

Biogas is a mixture of methane (60%) and carbon dioxide (40%), produced by anaerobic digestion of organic material, usually animal dung, human excreta and crop residue. Small-scale biogas digesters provide fuel for domestic lighting, cooling and cooking (see Anaerobic Biogas Reactor). Large-scale biogas plants are able to produce sufficient gas to fuel engines to generate electricity. The (thermal) energy available from biogas is about 6 kWh/m³. This corresponds to half a litre of diesel oil and 5.5 kg of firewood. 1 kg of human faeces generates about 50 litres of biogas: 1 kg of cattle dung delivers 40 litres of biogas, and 1 kg of chicken droppings generates about 70 litres of biogas.

Biogas as source of energy, in Bangladesh (for credits, click the picture)

Advantages	Disadvantages
Clean energy supply, reduces non-renewable energy use and decreases respiratory disease. Reduces workload in collecting firewood and in cooking. Deforestation and soil erosion can be reduced.	Biogas lamps have lower efficiency compared to using kerosene.

Applying conditions

• The main prerequisite of biogas use is the availability of specially designed biogas burners or modified consumer appliances.
• In some cases, especially at larger scale, further treatment or conditioning of biogas is necessary before it is ready to use. Treatment aims to remove water, hydrogen sulphide or carbon dioxide from the raw gas.
• Safety measures are needed, especially to reduce the risk of explosion in case of leakages.

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External links

• General information about Biogas as source of energy www.snvworld.org
• General information http://www5.gtz.de/gate/