Question

is methane good or bad for the environment ? (in one part of the book it is given that large amounts of methane is released which is a disadvantage and it is also written that bio gas is a excellent fuel which contains upto 75% of methane)

Answer 1

if methane is released unburnt then it is harmful as it is green house gas.
if the methane is used and burnt as fuel then less pollution in comparison to other conventional fuel.