Question

A student studies that biogas contains a large amount of methane which can be used as a fuel for various uses.
It burns without releasing smoke and leaving no residue like ash in other fossil fuel. Should biomass be considered a ‘good’ or ‘bad’ source of energy?

1. bad, as it does not release smoke
2. good, as it produces methane gas
3. bad, as it burns without releasing smoke
4. good, as it does not cause any harm to the environment