CBG or Compressed Bio Gas consists of mainly methane (more than 90%) and other gases like carbon dioxide (less than 4%), etc. CBG is produced by anaerobic digestion of biomass and waste sources like agricultural residue, cattle dung, sugarcane press mud, municipal solid waste, sewage treatment plant waste, etc.

This Biogas can be purified to remove hydrogen sulphide (H2S), carbon dioxide (CO2), water vapor and when this purified biogas (methane content more than 90%) is compressed to maximum 250 bar and filled up in cascades (group of high pressure cylindrical vessels), it is called Compressed Bio Gas or CBG.