Animals as energy resources. 

Animals as energy resources.

Biogas production from plants
What is biogas?
It is a methane that is produced from the rotting organic matter.

The waste plant materials.
1.  Cow dung.
2. Plant materials.
3. Animal urine.

Steps of making biogas digester.
The above materials are put into an air-tight container called a biogas digester.
where they are worked on by anaerobic bacteria to ferment and biogas is formed.
When the gas formation stops, the remains can be used as manure.

Structure of Biogas digester

biogas digester

Uses of the parts.

  • Inlet: For inserting in plant and animal matter.
  • Inlet pipe: allows plant and animal matter into the digester.
  • Outlet: For removing old used up matter to the garden.
  • Emptying tank: Where used up matter  is collected before it is taken to the garden.
  • Biogas tube: It traps biogas and takes it to the heating or lighting equipment.
    Uses of biogas
    1. For cooking
    2. For lighting
    3. For heating.

Advantages of using biogas
1. It is cheaper than using natural gas
2. It does not pollute the environment.
3. The materials are readily available in the environment.


  1. In which one way do plants depend on?
  2. Cattle    b) human beings      c) goats
  3. Mention any one advantage of using biogas over using firewood.
  4. How is a biogas digester important in the production of biogas?
  5. Cite any one thing used in the making of biogas.
  6. Write down any three ways how animals depend on non living things in the environment.
  7. In what way can a farmer use the residue left after making bio gas.
  8. State any two uses of biogas to human beings.
  9. Why is wind said to be a form of energy?
  10. How does use of biogas contribute towards the control of environmental degradation?
  11. What danger caused when biogas containers are kept near the reach of young children?