Natural gas
Natural gas is a naturally occurring hydrocarbon gas mixture consisting primarily of methane, but commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxide, nitrogen, hydrogen sulfide, or helium. It is formed when layers of decomposing plant and animal matter are exposed to intense heat and pressure under the surface of the Earth over millions of years. The energy that the plants originally obtained from the sun is stored in the form of chemical bonds in the gas.
Natural gas is found in deep underground rock formations or associated with other hydrocarbon reservoirs in coal beds and as methane clathrates. Petroleum is another resource and fossil fuel found in close proximity to and with natural gas. Most natural gas was created over time by two mechanisms: biogenic and thermogenic. Biogenic gas is created by methanogenic organisms in marshes, bogs, landfills, and shallow sediments. Deeper in the earth, at greater temperature and pressure, thermogenic gas is created from buried organic material.
Natural gas was discovered accidentally in ancient China, as it resulted from the drilling for brines. Natural gas was first used by the Chinese in about 500 BC (possibly even 1000 BC). They discovered a way to transport gas seeping from the ground in crude pipelines of bamboo to where it was used to boil salt water to extract the salt, in the Ziliujing District of Sichuan.
The discovery and identification of natural gas in the Americas happened in 1626. In 1821, William Hart successfully dug the first natural gas well at Fredonia, New York, United States, which led to the formation of the Fredonia Gas Light Company. The state of Philadelphia created the first municipally owned natural gas distribution venture in 1836. By 2009, 66 000 km? (or 8%) had been used out of the total 850 000 km? of estimated remaining recoverable reserves of natural gas. Based on an estimated 2015 world consumption rate of about 3400 km? of gas per year, the total estimated remaining economically recoverable reserves of natural gas would last 250 years at current consumption rates. An annual increase in usage of 2Ö3% could result in currently recoverable reserves lasting significantly less, perhaps as few as 80 to 100 years.
