Compressed Natural Gas

CNG is often confused with LNG. While both are stored forms of natural gas, the key difference is that CNG is in compressed form, while LNG is in liquefied form. CNG has a lower cost of production and storage compared to LNG as it does not require an expensive cooling process and cryogenic tanks. CNG requires a much larger volume to store the same mass of natural gas and the use of high pressures.

CNG is also often confused with LPG, which is a compressed blend of propane (C3H8) and butane (C4H10). Following are the main advantages of Compressed Natural Gas:

The Environmentally Clean Advantage

• Compressed natural gas is the cleanest burning fuel operating today. This means less vehicle maintenance and longer engine life.
• CNG vehicles produce the fewest emissions of any motor fuel.
• Dedicated Natural Gas Vehicles (NGV) have little or no emissions during fueling. In gasoline vehicles, fueling emissions account for at least 50% of a vehicle's total hydrocarbon emissions.
• CNG produces significantly less pollutants than gasoline.
• Tailpipe emissions from gasoline operated cars release carbon dioxide, which contributes to global warming. This is greatly reduced with natural gas.

The Maintenance Advantage

• Some fleet operators have reduced maintenance costs by as much as 40% by converting their vehicles to CNG.
• Intervals between tune-ups for natural gas vehicles are extended 30,000 to 50,000 miles.
• Intervals between oil changes for natural gas vehicles are dramatically extended--anywhere from 10,000 to 25,000 additional miles depending on how the vehicle is used.
• Natural gas does not react to metals the way gasoline does, so pipes and mufflers last much longer.

The Performance Advantage

• Natural gas gives the same mileage as gasoline in a converted vehicle.
• Dedicated CNG engines are superior in performance to gasoline engines.
• CNG has an octane rating of 130 and has a slight efficiency advantage over gasoline.
• Because CNG is already in a gaseous state, NGV's have superior starting and drivability, even under severe hot and cold weather conditions.
• NGV's experience less knocking and no vapor locking.

The CNG Cost Advantage
Natural gas is cheaper per equivalent gallon than gasoline (an average of 15% to 50% less than gasoline).

The Safety Advantage
Surveys indicate that NGV's are as safe or safer than those powered by other fuels. A 1992 AGA survey of more than 8,000 vehicles found that with more than 278 million miles traveled, NGV injury rates per vehicle mile traveled were 34% lower than the rate for gasoline vehicles. There were no fatalities reported--even though these vehicles were involved in over 1,800 collisions.

CNG Conversions
Converting a gasoline-powered car to CNG requires only minor engine modifications. To learn more about converting your car, please contact a certified CNG conversion technician.