| Compressed Natural Gas (CNG) Information |
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Compressed Natural Gas (CNG)
Benefits
Natural gas is a domestically available, inherently clean-burning fuel. Using compressed natural gas (CNG) as vehicle fuel increases energy security, paves the way for fuel cell vehicles, and improves public health and the environment. Using renewable natural gas provides even more benefits.
Emissions
Compared with vehicles fueled by conventional diesel and gasoline, natural gas vehicles can produce significantly lower amounts of harmful emissions such as nitrogen oxides, particulate matter, and toxic and carcinogenic pollutants as well as the greenhouse gas carbon dioxide. The U.S. Environmental Protection Agency has called the natural gas Honda Civic GX the cleanest internal-combustion vehicle on Earth. Reduce carbon monoxide emissions 90%-97%
- Reduce carbon dioxide emissions 25%
- Reduce nitrogen oxide emissions 35%-60%
- Potentially reduce non-methane hydrocarbon emissions 50%-75%
- Emit fewer toxic and carcinogenic pollutants
- Emit little or no particulate matter
- Eliminate evaporative emissions
Manufacturing
Most natural gas consumed in the United States is domestically produced, with significant importation from Canada and a small but rapidly growing contribution from overseas imports in the form of liquefied natural gas (LNG).
The vast majority of natural gas is a fossil fuel, formed over millions of years by the action of heat and pressure on organic material (ancient plants and animals). It is derived in much smaller amounts from renewable sources such as landfill gas and water/sewage treatment. Other supplemental sources include synthetic gas and coal-derived gas. See the Energy Information Administration natural gas production page for more information.
Gas trapped in sub-surface porous rock reservoirs is extracted via drilling. Gas streams produced from oil and gas reservoirs contain natural gas, liquids, and other materials. Processing is required to separate the gas from petroleum liquids and to remove contaminants.
First, the gas is separated from free liquids such as crude oil, hydrocarbon condensate, water, and entrained solids. The separated gas is further processed to meet specified requirements. For example, natural gas for transmission companies must generally meet certain pipeline quality specifications with respect to water content, hydrocarbon dewpoint, heating value, and hydrogen-sulfide content.
A dehydration plant controls water content, a gas processing plant removes certain hydrocarbon components to hydrocarbon dewpoint specifications, and a gas sweetening plant removes hydrogen sulfide and other sulfur compounds (when present).
The United States has a vast natural gas distribution system, which can quickly and economically distribute natural gas to and from almost any location in the lower 48 states. Gas is distributed between and within states by 300,000 miles of transmission pipelines (see map). An additional 1.9 million miles of distribution pipes transport gas within utility service areas. The distribution system also includes thousands of delivery, receipt, and interconnection points; hundreds of storage facilities; and more than 50 points for exporting and importing natural gas.
Most natural gas fueling stations dispense compressed natural gas (CNG), which is either compressed on site or compressed off site and transported to the station in tanks.
Safety
Although CNG is a flammable gas, it has a narrow flammability range, making it an inherently safe fuel. Strict safety standards make CNG vehicles as safe as gasoline-powered vehicles. In the event of a spill or accidental release, CNG poses no threat to land or water; it is nontoxic. CNG also disperses rapidly, minimizing ignition risk relative to gasoline. Natural gas is lighter than air and will not pool as a liquid or vapor on the ground
Costs
Just like gasoline prices, the cost of natural gas fluctuates; however, the cost of natural gas is typically less than that of unleaded fuel.
Availability
Available at an increasing number of retail stations (784 in 45 states). Home refueling appliances are also available. Oregon’s infrastructure is currently limited to the three State Motor Pools and a few retail stations in Medford and Hillsboro.
CNG Fuel Vehicles in DAS Fleet
- Chevrolet 2500 Cargo Van
- Ford Crown Victoria
- Ford E250 Cargo Van
- Honda Civic GX
Source: US Department of Energy, Energy Efficiency and Renewable Energy, Alternate Fuels & Advanced Vehicles Data Center: http://www.afdc.energy.gov/afdc/
Updated: 02/12/2009
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