Natural gas is one of the cleanest burning alternative fuels. It is a fossil fuel comprised mostly of methane with small amounts of ethane, propane, and other gases. It occurs naturally in the earth and is extracted from gas and oil wells. Small amounts are derived from synthetic gas, landfill gas, biogas, and coal-derived gas.

Natural gas has a high octane rating and is non-toxic, non-corrosive, and non-carcinogenic. It is lighter than air and burns almost completely, with by-products being carbon dioxide and water.

Natural Gas as a Fuel
Natural gas must be used either in the form of compressed natural gas (CNG) or liquefied natural gas (LNG) to fuel cars and trucks. Both CNG and LNG are defined as alternative fuels.

Most natural gas fueling stations dispense CNG. The availability of LNG stations is more limited because most users are fleets that have LNG infrastructure dedicated to their vehicles.

Natural gas can be blended with hydrogen to make HCNG.

Natural Gas Vehicles
Bi-fuel vehicles that separately run on natural gas and either gasoline or diesel allow drivers to use the conventional fuel when the cleaner, more economical natural gas alternative is unavailable.

Natural gas vehicles are not produced commercially in large numbers; however, gasoline and diesel vehicles can be converted to run on CNG.

LNG vehicles are mainly fleet vehicles and heavy-duty trucks.

To determine if switching to natural gas is cost-effective for your fleet, use this cost calculator.

Benefits of natural gas:

• Typically cost 1/3 less than gasoline at the pump
• 87% of natural gas used by the U.S. is domestically produced
• Results in lower greenhouse gas emissions, by 30-40% compared to unleaded gasoline
• An efficient source of hydrogen

U.S. Natural Gas Pipeline Network



Additional Resources:

• www.ngvc.org/index.html
• www.fueleconomy.gov/feg/bifueltech.shtml
• www.eere.energy.gov/afdc/vehicles/natural_gas.html
• www.eere.energy.gov/afdc/fuels/natural_gas.html
• www.afvi.org/index.html

Natural Gas Fueling Station Locations

• www.eere.energy.gov/afdc/fuels/natural_gas_locations.html

CNG is stored onboard a vehicle in tanks at high pressure, typically between 2,000 and 3,600 pounds per square inch (psi). CNG-powered vehicles get about the same fuel economy as a gasoline vehicle on a gasoline gallon equivalent basis.

The Honda Civic GX is the only OEM CNG vehicle available in the U.S. The Honda GX gets 28 mpg in the city and 39 mpg on the highway. The EPA calls the Civic GX the cleanest burning internal combustion vehicle on Earth.

Gasoline or diesel dedicated vehicles can be converted to run on CNG, and is cost-effective over the lifespan of the vehicle due to fuel cost savings.

Light-duty Vehicle Emissions
Compared to light-duty gasoline vehicles, using CNG results in:

• Reducing carbon monoxide emissions 90%-97%
• Reducing carbon dioxide emissions 25%
• Reducing nitrogen oxide emissions 35%-60%
• Potentially reducing non-methane hydrocarbon emissions 50%-75%
• Emitting fewer toxic and carcinogenic pollutants
• Emitting little or no particulate matter
• Eliminating evaporative emissions

To store a larger amount of fuel onboard a vehicle, natural gas is liquefied by cooling the gas to -260°F. Because LNG must be kept at such cold temperatures, the fuel is stored in double-wall, vacuum-insulated pressure vessels.

LNG is typically used in heavy-duty vehicles OEM modified for this fuel, such as:

• School buses
• Transit buses (roughly 22% of all new transit bus orders are for natural gas)
• Delivery vehicles
• Airport shuttles
• Street sweepers
• Other heavy-duty vehicles

Heavy-duty Vehicle Emissions
Compared to heavy-duty diesel vehicles, using LNG results in:

• Producing half the particulate matter of average diesel vehicles
• Reducing carbon monoxide emissions
• Reducing nitrogen oxide and volatile organic hydrocarbon emissions by 50%
• Potentially reducing carbon dioxide emissions 25%
• Reducing toxic and carcinogenic pollutants