Biogas is a gas produced by the biological breakdown of organic matter in the absence of oxygen.
It is a mixture of methane(65%) , Carbon dioxide , hydrogen, hydrogen sulphide etc.
Its considered an ideal fuel because:
1. It burns without smoke and leaves no residue.
2. Its heat capacity is high.
3. Animal and food waste and sewage undergo natural anaerobic digestion in an oxygen-free environment.Therefore, biogas is included in the category of renewable energy sources because till humans and animals exist on the planet, biogas will go on being produced.