When you flick on your gas stove to make a cup of coffee, you may be at the receiving end of a delivery system reaching more than 1,000 miles.
Natural gas, created by the decomposition of organic matter, becomes trapped in pockets hundreds of feet below the earth’s surface.
Shafts are drilled into those pockets to obtain the gas, which is fed into transmission lines as large as 42 inches in diameter. The gas is pumped at high pressures over great distances through an extraordinary network of pipelines that supplies the entire country.
New York City’s gas, for example, comes all the way from Texas and Louisiana, traveling for five days at 15 miles per hour.
When the gas arrives at its destination, the pipeline companies route it to metering control stations operated by the local gas company. Pressure in the pumped gas is reduced and a chemical added to give gas the distinctive smell we associate with it. Natural gas is in fact odorless, and dangerous leaks could go undetected if the scent chemical were not added.
Metal or plastic pipes, mains and service pipes, carry gas underground to your house or apartment building. These pipes are embedded in sand and surrounded by fill at least 3 feet underground.
Checkpoints occur at regular intervals throughout the system, consisting of two manholes, 25 feet apart, each equipped with a filter to clean gas of any dirt particles and a regulator to increase or decrease the rate of flow. The manholes are on the same main, but an alternate pipe can divert the gas before the first manhole and return it after the second in the event that problems arise with the regulators.
The pressure in some gas lines also may be monitored at a central control office. Mains branch into smaller service lines with control valves to supply each house or apartment building. These in turn channel the gas to the heaters, air conditioners, or stoves in your home.
In order to meet high demand for gas in winter, some companies store huge quantities in steel tanks in the form of liquefied natural gas (LNG). Gas is taken directly from the pipelines, cleaned, and chilled to an extremely low temperature of, -260 degrees Fahrenheit. As it cools, the gas shrinks.
In liquid form it occupies only 1/600 of the space it does as a vapor, making it convenient to store and to transport over land.