The most widely used description of natural gas relates to pockets of methane and other carbon based gases that have become trapped thousands of feet underground. This gas is reached in much the same way as crude oil. Its origins are also similar to crude oil.
This gas is produced when anything living on the earth is buried and sealed away during decomposition. The microbes that are the agents of decay produce this gas a byproduct. Because it is trapped under layers of mud and rock, the gas slowly collects into pockets deep in the earth. A pocket of natural gas is much like a balloon. It usually builds up pressure until it is released in some fashion. Frequently this is caused by a well being drilled to tap the pocket.
Most natural gas is refined before shipment to the customer. The refining process removes a number of other gases like helium from the natural gas. In this way, the final product becomes a relatively clean burning fossil fuel. It is shipped across the country by means of high pressure pipelines. The pressure is reduced before piping into homes for heating, cooking, hot water heating, etc.
Other natural gas is compressed into liquid form. Propane and butane are two of the more common liquefied natural gases. The large shiny tanks that are found in many rural backyards are propane tanks. On most gas appliances, the size of the orifice has to be changed in the fuel inlet to the appliance to go from natural gas to propane or vice versa. Because of the additional pressure of liquefied gas, a smaller opening is needed.
Natural gas in all forms is extremely volatile. Just a small spark will ignite it. If it becomes concentrated in room or house, the spark can cause a devastating explosion. To help prevent this and asphyxiation, natural gas has a substance added to it to give it a scent that is easily detectable by smell. In its natural state, this gas has neither color nor odor.
When used as compressed propane, this fuel has been gaining popularity as an alternative fuel for automobiles. The conversion to this type of fuel is relatively cheap and easy. As long as it is installed properly, propane offers no extra risk over gasoline as a fuel and burns much cleaner. Many drivers have reported a slight drop in vehicle power, but the cost savings is normally considered worth it.