Natural gas is a gaseous mixture of hydrocarbons, predominantly methane (CH4). It is a fossil fuel formed from the remains of plants and animals that have been subjected to heat and pressure over millions of years. Natural gas is used as a fuel for heating, cooking, and electricity generation. It is also used as a transportation fuel in vehicles such as buses, trucks, and cars.
Key Facts
- Composition: Natural gas is a gaseous mixture of hydrocarbons, predominantly methane (CH4). The typical composition of natural gas before it is refined can vary, but it generally includes methane, ethane (C2H6), propane (C3H8), butane (C4H10), carbon dioxide (CO2), oxygen (O2), nitrogen (N2), hydrogen sulfide (H2S), and trace amounts of rare gases.
- Methane: Methane is the primary component of natural gas, accounting for 70-90% of its composition. It is a molecule made up of one carbon atom and four hydrogen atoms (CH4).
- Natural gas liquids (NGLs): Natural gas also contains smaller amounts of NGLs, which are hydrocarbon gas liquids. These include ethane, propane, butane, and pentane.
- Nonhydrocarbon gases: Natural gas may also contain nonhydrocarbon gases such as carbon dioxide (CO2) and water vapor.
Composition of Natural Gas
The composition of natural gas can vary depending on the source and the processing it has undergone. However, the typical composition of natural gas before it is refined includes the following components:
- Methane (CH4)Methane is the primary component of natural gas, accounting for 70-90% of its composition. It is a molecule made up of one carbon atom and four hydrogen atoms.
- Ethane (C2H6)Ethane is a hydrocarbon gas with two carbon atoms and six hydrogen atoms. It is typically present in natural gas in amounts ranging from 0 to 20%.
- Propane (C3H8)Propane is a hydrocarbon gas with three carbon atoms and eight hydrogen atoms. It is typically present in natural gas in amounts ranging from 0 to 10%.
- Butane (C4H10)Butane is a hydrocarbon gas with four carbon atoms and ten hydrogen atoms. It is typically present in natural gas in amounts ranging from 0 to 5%.
- Carbon Dioxide (CO2)Carbon dioxide is a nonhydrocarbon gas that is typically present in natural gas in amounts ranging from 0 to 8%.
- Oxygen (O2)Oxygen is a nonhydrocarbon gas that is typically present in natural gas in amounts ranging from 0 to 0.2%.
- Nitrogen (N2)Nitrogen is a nonhydrocarbon gas that is typically present in natural gas in amounts ranging from 0 to 5%.
- Hydrogen Sulfide (H2S)Hydrogen sulfide is a nonhydrocarbon gas that is typically present in natural gas in amounts ranging from 0 to 5%. It is a toxic gas that can cause health problems if inhaled.
- Rare GasesTrace amounts of rare gases, such as helium and argon, may also be present in natural gas.
Natural Gas Liquids (NGLs)
Natural gas also contains smaller amounts of NGLs, which are hydrocarbon gas liquids. These include ethane, propane, butane, and pentane. NGLs are typically removed from natural gas during processing and sold separately as fuels or petrochemical feedstocks.
Nonhydrocarbon Gases
Natural gas may also contain nonhydrocarbon gases such as carbon dioxide (CO2) and water vapor. These gases are typically removed from natural gas during processing to meet pipeline specifications.
Sources
- U.S. Energy Information Administration: Natural Gas Explained
- Alternative Fuels Data Center: Natural Gas Fuel Basics
- Natural Gas Supply Association: Background
FAQs
What is natural gas composed of?
Natural gas is primarily composed of methane (CH4), which typically accounts for 70-90% of its volume. It also contains smaller amounts of other hydrocarbon gases, such as ethane, propane, and butane, as well as nonhydrocarbon gases like carbon dioxide and water vapor.
What is methane?
Methane is a colorless, odorless, and flammable gas with the chemical formula CH4. It is the simplest hydrocarbon and the main component of natural gas, accounting for 70-90% of its composition. Methane is also a potent greenhouse gas, with a global warming potential 25 times greater than carbon dioxide.
What are natural gas liquids (NGLs)?
Natural gas liquids (NGLs) are hydrocarbon gas liquids that are found in natural gas. These include ethane, propane, butane, and pentane. NGLs are typically removed from natural gas during processing and sold separately as fuels or petrochemical feedstocks.
What are nonhydrocarbon gases found in natural gas?
Nonhydrocarbon gases that may be present in natural gas include carbon dioxide (CO2), water vapor, nitrogen (N2), hydrogen sulfide (H2S), and trace amounts of rare gases such as helium and argon. These gases are typically removed from natural gas during processing to meet pipeline specifications.
Why is hydrogen sulfide removed from natural gas?
Hydrogen sulfide (H2S) is a toxic gas that can cause health problems if inhaled. It is typically removed from natural gas during processing to protect consumers and workers.
What are the environmental impacts of natural gas?
Natural gas is a fossil fuel, and its combustion releases greenhouse gases, including carbon dioxide (CO2) and methane (CH4). Methane is a particularly potent greenhouse gas, with a global warming potential 25 times greater than carbon dioxide. Natural gas also contains impurities such as sulfur and nitrogen compounds, which can contribute to air pollution.
Is natural gas a renewable resource?
Natural gas is a non-renewable resource because it is formed from the remains of plants and animals that have been subjected to heat and pressure over millions of years. However, renewable natural gas (RNG) can be produced from organic materials such as landfill waste and agricultural residues. RNG is chemically identical to conventional natural gas and can be used as a transportation fuel or injected into the natural gas grid.
What are the benefits of using natural gas?
Natural gas is a relatively clean-burning fossil fuel that produces fewer emissions than coal or oil. It is also a versatile fuel that can be used for heating, cooking, electricity generation, and transportation. Natural gas is also a domestically produced fuel, which reduces the need for imports.