17-3 Natural Gas

What Is Natural Gas? Mostly Methane

In its underground gaseous state, natural gas is a mixture of 50–90% by volume of methane (CH4), the simplest hydrocarbon.

Conventional natural gas lies above most reservoirs of crude oil. Like oil, natural gas was formed from fossil deposits of phytoplankton and animals buried on the seafloor for millions of years and subjected to high temperatures and pressures. However, unless a natural gas pipeline has been built, deposits of natural gas found above oil deposits cannot be used.

Unconventional natural gas is found in other underground sources. One example is shale gas, which is associated with certain rock formations.

When a natural gas field is tapped, propane and butane gases are liquefied and removed as liquefied petroleum gas (LPG). LPG is stored in pressurized tanks for use mostly in rural areas not served by natural gas pipelines. The rest of the gas (mostly methane) is dried to remove water vapour. Then it is cleansed of poisonous hydrogen sulphide and other impurities and pumped into pressurized pipelines for distribution. At a very low temperature natural gas can be converted to liquefied natural gas (LNG).

How Is Natural Gas Used? A Versatile Fuel

Natural gas is a versatile fuel that can be burned to heat water and buildings and to generate electricity. It can also be used as a fuel for cars and trucks with fairly inexpensive engine modifications. Natural gas is especially useful for running fleets of taxis and delivery and work vehicles operating from garages and maintenance facilities that can be used to supply them with this fuel.

Increasingly, natural gas is used to run medium-sized turbines that produce electricity. These clean-burning turbines have a much higher energy efficiency (50–60%) than coal-burning power plants (24–35%).

Who Has the World’s Natural Gas Supplies, and How Long Will the Supplies Last? More Abundant Than Oil

Russia has about 25% of the world’s proven natural gas reserves, followed by Iran (15%) and Qatar (14%). About 41% of the world’s natural gas reserves are in Middle Eastern countries. Geologists expect to find more natural gas, especially in unexplored developing countries.

The long-term global outlook for natural gas supplies is better than for conventional oil. At the current consumption rate, geologists estimate that known reserves and undiscovered potential reserves of conventional natural gas should last the world for 62–125 years depending on how rapidly it is used.

What Is the Future of Natural Gas in Canada and the United States? Declining Supplies

Today, Canada has surplus natural gas and exports 58% of its annual production to the United States. Both countries use natural gas to heat homes, and the United States burns natural gas to produce 16% of the country’s electricity.

More liquefied natural gas could be imported by ship. But this requires cooling the gas to a very low temperature to liquefy it, shipping it in special tankers, and building special LNG receiving terminals. This is quite expensive and reduces the net energy yield for natural gas. Also, LNG is highly flammable and could lead to large-scale fires at receiving terminals.