The term “natural gas” actually describes a mixture of several different naturally occurring gases. While natural gas is typically made up mostly of methane, it can contain small percentages of other materials, including ethane, butane, propane, and pentane. The unifying factor among these different gases is that they are all hydrocarbons. This simply means that these molecules are entirely made up of the elements carbon and hydrogen. Energy is stored in the bonds between these elements and can be released and harvested through the combustion, or burning, of the hydrocarbon.