Biogas
- Is a renewable source of energy that is made mostly of methane.
- The gas is formed when biological matter like cow manure or kitchen waste is decomposed in special biogas digesters.
Production of biogas
- Fresh cow dung is collected and then mixed with water to form sludge.
- Organic wastes are added to the digester and mixed with water.
- The anaerobic bacteria start to break down the organic wastes. Solid wastes collect at the bottom.
- The biogas rises to the top of the digester and the gas can be piped off and used in homes for cooking, lighting.
- The digested sludge (slurry) is collected and used as a fertiliser for farms or gardens.
- The digester is built underground so that the heat produced during decomposition is retained and facilitates further decomposition of the cow dung
Factors affecting the production of biogas
- Nature of waste
- Time
- Anaerobic bacteria
- pH between 6 & 8
- Suitable temperature of about 25-60oC
- Air
Uses of biogas
- Cooking – Lighting
- Operating a refrigerator