It is so because CH4
is a potent green house gas and
its Global Warming Potential (GWP) is 21. The latter
means that CH4
will cause 21 times as much warming
as an equivalent mass of CO2
. Therefore the abatement
of CH4
emission from CNG vehicular exhaust is of
paramount importance, as CH4
emissions from CNG
fuelled vehicles are much more in comparison to diesel
and gasoline fuelled vehicles.