San Diego Regional Energy Office  


Ethanol and E85

Natural Gas

Hydrogen and Fuel Cells

Electric Battery Vehicles

Hybrid Electric Vehicles

Fuel Conservation

Public Transportation

Home  > TECHNOLOGIES  > Transportation  > Natural Gas

Natural Gas

What is Natural Gas?
Natural gas is a gaseous fossil fuel consisting primarily of methane. It is found in oil fields and natural gas fields, as well as in coal beds (in smaller quantities). The primary component of natural gas is methane (CH4), the shortest and lightest hydrocarbon molecule. It may also contain heavier gaseous hydrocarbons such as ethane (C2H6), propane (C3H8) and butane (C4H10), as well as other sulphur containing gases.

Natural gas as a transportation fuel.
Compressed natural gas (CNG) and liquified natural gas (LNG) can be used as a clean alternative to other automobile fuels in anything from cars to 18-wheelers (PDF).

CNG vehicles use natural gas stored in cylinders at pressures of 2,000 pounds to 3,500 pounds per square inch. Compressed natural gas is used in light-duty passenger vehicles and pickup trucks, medium-duty delivery trucks, and in-transit and school buses. Dedicated CNG vehicles are designed to run only on CNG and bi-fuel CNG vehicles have two separate fueling systems that enable the vehicle to use either CNG or gasoline.

LNG is natural gas turned into liquid for easy storage or transport by extreme cooling to minus 263.2 degrees Fahrenheit. The requirements of keeping the liquid very cold, along with its volatility, make liquid hydrogen’s applications more limited for transportation purposes. LNG is typically used in heavy-duty applications such as transit buses, heavy-duty long-haul trucks or locomotives.

Where can I find vehicles that run on natural gas?
According to the Natural Gas Vehicle Coalition (NGVC), there are 130,000 NGVs in the United States and 2 million worldwide. The Alternative Fuels Data Center provides a list of light duty dedicated and light duty bi-fuel CNG vehicles.

What are the differences/advantages of natural gas vehicles?
Natural gas vehicles tend to cost $4,000 to $8,000 more than gasoline-powered vehicles. Some natural gas vehicle owners have reported service lives 2 to 3 years longer than gasoline or diesel vehicles, as well as extended time between required maintenance.

Natural gas is now cost-competitive with gasoline, and more recently, has been cheaper as a transportation fuel.

Using natural gas as a transportation fuel also reduces our reliance on energy imports. Approximately 85 percent of the natural gas Americans use is produced domestically, and around 13 percent comes from Canada. This means that 98 percent of our natural gas supply comes from North America. This is a stark contrast to our petroleum supply, where over 60 percent is imported.

What are environmental characteristics of natural gas vehicles?
CNG vehicles generate fewer exhaust and greenhouse gas emissions than their gasoline- or diesel-powered counterparts. Compared with most gasoline-powered vehicles, dedicated NGVs typically reduce the emissions of carbon monoxide by approximately 70 percent, non-methane organic gas (NMOG) by 89 percent, and oxides of nitrogen (NOx) by 87 percent.

NGVs also emit virtually no particulate matter emissions, a pollutant that has increasingly come under scrutiny from health and air quality officials.

The San Diego Metropolitan Transit System began acquiring compressed natural gas buses in 1996, and now has more than 140 of these buses in service.

Where are the natural gas fueling stations?
CNG is currently available at approximately 1,300 refueling stations in 46 states, and this number continues to grow. In addition, CNG vehicle owners can refuel their cars at home by installing small compressors connected directly to the home’s natural gas supply.

California has more than 140 public fueling sites and an additional 200 private fleet fueling sites. Here is the California Natural Gas Fueling Station Directory (PDF) from the California NGV Coalition.

In San Diego County, there is a network of 17 private and public natural gas-fueling stations, and four new public refueling stations are planned. Click here for a list of the compressed natural gas fueling stations in the San Diego region.

Other Resource Links:
Natural Gas Vehicle Technology Forum
The Natural Gas Vehicle Coalition
California Natural Gas Summary

California Center for Sustainable Energy

©2008, California Center for Sustainable Energy
Privacy Policy | Terms of Use | Site Map