 Burning natural gas results in lower emissions of sulfur dioxide, particulate matter, and 20% less carbon dioxide than gasoline or diesel. It is one of the cleanest burning fuels. Natural gas is non-toxic, non-corrosive, less combustible than most other fuels, and has few associated health risks. CNG is stored under high pressures. The range of flammability and combustion is much narrower with CNG, making it safer than gasoline. The flashpoint for gasoline is 250 degrees whereas the flashpoint for natural gas is 1100 degrees. Natural gas is lighter than air and will dissipate if leaked whereas gasoline will sink and puddle. Dedicated NGVs produce little or no evaporative emissions during fueling and use. In gasoline vehicles, evaporative and fueling emissions account for at least 50% of a vehicle's total hydrocarbon emissions.
Exposure to the levels of suspended fine particulate matter found in many U.S. cities has been shown to increase the risk of respiratory illness and other health problems. Much of the particulate matter in urban areas is due to transportation. Natural gas produces only tiny amounts of particulate matter. Natural gas is abundant, low-cost, and domestically produced.
CNG reduces:
- Benzene emissions by 97% compared to diesel and 99% compared to gasoline
- Nitrogen oxides by 87% compared to diesel and 35-60% compared to gasoline
- Carbon dioxide by 10% compared to diesel and 25% compared to gasoline
- Carbon monoxide by 90-97% compared to gasoline
- Non-methane hydrocarbons by 50-75% compared to gasoline
- Lead and sulfur emissions by 100% compared to both diesel and gasoline
- Smoke and particulate matter (PM10) significantly
|
Front page
Natural gas vehicles (NGV) are the most advanced alternative fuel technology available commercially. According to the Environmental Protection Agency, there are more than 85,000 CNG vehicles on the road, including one out of every five transit buses. Some vehicles come already equipped to run either entirely on CNG (dedicated) or on both CNG and gasoline or diesel (bi-fuel). Additionally, some vehicles can be converted to run on CNG. Both light and heavy-duty vehicles can utilize CNG. All U.S.-based, full-sized transit bus manufacturers offer CNG buses. Applications include transit and school buses, refuse trucks, light-duty vehicles, vans, passenger cars and taxis. LNG is not suitable for light-duty vehicles but is an ideal fuel for large (class 8) trucks, transit buses, and medium-duty fleet trucks. There are over 110,000 NGVs on the road in the U.S. fueling at 1,300 locations. Over half of these sites are commercially accessible. 
Vehicles running on CNG may have reduced range as compared to similar gasoline model vehicles. This is a limitation of the fuel storage tanks rather than a limitation of the fuel. For example a dedicated CNG Honda Civic GX has an eight-gallon tank and a gasoline powered Civic has an eleven-gallon tank. However, NGVs experience the same fuel economy with CNG as they do with gasoline. Bi-fuel vehicles have a longer range because they have two fuel tanks and can run on gasoline or diesel in addition to CNG. Because methane does not have to vaporize before being burned with oxygen, natural gas can burn cleaner, especially at colder temperatures than gasoline or diesel. LNG is kept at very low temperatures to increase storage capability and therefore provides longer ranges than CNG. Vehicles operating on CNG and LNG have a longer engine life and require less frequent oil change intervals.