Compressed Natural Gas $(\mathrm{CNG})$ is the best, cheap fuel, that has replaced petrol and diesel fuel and is considered as clean fuel. it consists of around $90 \%$ methane, by compressing it to less than $1 \%$ of volume it occupies at standard atmospheric pressure. Propane and butane together form LPG or liquified petroleum gas while ethane is used in chemical industry to produce ethene.