Natural Gas

Natural gas has its origins in decayed living matter, most likely as the result of the action of bacteria upon dead animal and plant material. In order for most bacteria to effectively break down organic matter to hydrocarbons, there must be low levels of oxygen present. This would mean that the decaying matter was buried (most likely under water) before it could be completely degraded to carbon dioxide and water. Conditions such as this are likely to have been met in coastal areas where sedimentary rocks and marine bacteria are common. The actions of heat and pressure along with bacteria produced a mixture of hydrocarbons. The smaller molecules which exist as gases were then either trapped in porous rocks or in underground reservoirs where they formed sources of hydrocarbon fuels.

Natural gas, like petroleum, is a mixture of many organic substances. The most common substances in natural gas are summarized in the following table.

Other gases such as oxygen, argon, and carbon dioxide make up the rest of most natural gas sources. The exact composition of different sources of natural gas varies slightly, but in all cases, methane is by far the most common component, with other hydrocarbons also being very common. The largest sources of natural gas in the United States are found in Alaska, Texas, Oklahoma, western Pennsylvania, and Ohio. It is estimated that the supply of natural gas in this country may be sufficient to last for two centuries, although the more readily accessible sources have been used, meaning that it will be more expensive to obtain natural gas in the future.