As nouns the difference between biomethane and biogas
is that biomethane is a biogas composed mostly of methane while biogas is a mixture of methane and carbon dioxide, produced by anaerobic digestion of organic waste matter, used as a fuel.
biomethane
English
Noun
(-)
A biogas composed mostly of methane biogas
English
Noun
(
wikipedia biogas)
A mixture of methane and carbon dioxide, produced by anaerobic digestion of organic waste matter, used as a fuel