Natural Gas & Propane
Natural gas is primarily composed of methane (CH4) and other hydrocarbons (ethane, propane, butane, etc.) that are removed prior to consumer use. Most natural gas is extracted from gas and oil wells, though some supplies can be found in biogas resources, like landfills. As transportation fuel, natural gas is compressed (CNG) or liquefied (LNG). CNG is made by compressing natural gas to a fraction of its volume. Like natural gas, CNG is used in gasoline internal-combustion vehicles that have been converted to alternative fuel vehicles, or AFVs, and is provided to these AFVs by high-pressure (up to 3,600 psi) compression and dispensing systems. The CNG is then stored on-board in high-pressure cylinders. LNG is produced by purifying and cooling natural gas to -260°F. It is particularly well suited to heavy-duty applications.
Propane, often referred to as liquefied petroleum gas (LPG), is a byproduct of natural gas processing and can also be refined from petroleum. It comes in liquid form and is compressed slightly and/or cooled. Stored under pressure inside a tank, propane turns into a colorless, odorless liquid. As pressure is released, the liquid propane vaporizes and turns into gas that is used for combustion. An odorant, ethyl mercaptan, is added for leak detection. Propane refueling facilities store and dispense the fuel as a liquid.
Both CNG and LPG offer significant environmental, energy security, and economic benefits. They produce lower tailpipe emissions and greenhouse gases than diesel or gasoline. Also unlike gasoline, CNG and LPG are non-toxic, non-corrosive, and non-carcinogenic and present no threat to soil, surface water, or groundwater. 85% of the CNG and LPG in use today in the US is domestically produced.
More Resources
- To find out more about natural gas and propane, please visit the Department of Energy's Alternative Fuel Data Center.
- To learn more about CNG and LNG vehicles, please visit Natural Gas Vehicles for America.
- For a collection of tools and resources for fleets wanting to evaluate using natural gas as a vehicle fuel, visit NG Toolkit.
- To find CNG and LPG stations near you, please visit the Alternative Fuel Data Center's station locator.
- To learn more about propane applications for fleets, please visit the Propane Education & Research Council.