Main constituents of biogas are methane and carbon dioxide.

1. Methane:
- Methane is the major component of biogas, typically making up 50-75% of its composition.
- It is a greenhouse gas that is produced during the anaerobic digestion process by the decomposition of organic matter in the absence of oxygen.
- Methane is a valuable fuel because it can be burned to produce heat, electricity, or used as a transportation fuel.

2. Carbon Dioxide:
- Carbon dioxide is the second most abundant component of biogas, comprising 25-50% of its composition.
- It is also produced during the anaerobic digestion process, as a byproduct of the microbial breakdown of organic matter.
- Carbon dioxide is a greenhouse gas, but it has a lower global warming potential compared to methane.
- It can be captured and used for various purposes, such as carbonation of beverages or in greenhouse cultivation.

Other constituents of biogas:
- In addition to methane and carbon dioxide, biogas can contain small amounts of other gases, including nitrogen, hydrogen, and trace amounts of other gases such as hydrogen sulfide and ammonia.
- Nitrogen is present in biogas due to the presence of nitrogen-containing compounds in the organic matter being digested.
- Hydrogen can be produced during the anaerobic digestion process, but its concentration in biogas is usually low.
- Hydrogen sulfide and ammonia are undesirable components of biogas as they can be corrosive and have a foul odor. Therefore, their levels need to be minimized.

Benefits of biogas:
- Biogas is a renewable energy source that can be produced from various organic waste materials, such as agricultural waste, food waste, sewage sludge, and animal manure.
- It helps in reducing greenhouse gas emissions by capturing and utilizing methane, which has a much higher global warming potential than carbon dioxide.
- Biogas can be used for heating, electricity generation, and as a vehicle fuel, providing a sustainable alternative to fossil fuels.
- The production and use of biogas also contribute to waste management and environmental sustainability by diverting organic waste from landfills and reducing the release of harmful pollutants into the environment.