Natural gas

From Conservapedia

Natural gas is a petroleum product consisting of about 75% methane. The rest is made up of ethane (15%) and other hydrocarbons.^[1] It is naturally oderless, so odor is added to make a leak detectible.

References

1. ↑ http://scifun.chem.wisc.edu/chemweek/methane/methane.html