Natural Gas is Safe - It comes as a surprise to many to hear that natural gas is one of the safest transport fuels available, CNG is actually safer than petrol.
In its natural state, natural gas is odourless. As a safety measure, the gas is odorised with Mercaptan prior to distribution to provide a ready means of leak detection. An average person can easily detect the smell of gas at a concentration as low as 0.3% by volume in air. That concentration is about 16 times lower than the level which will support combustion.
Natural gas has a high ignition temperature, about 1,200 degrees Fahrenheit, compared with about 600 degrees Fahrenheit for gasoline. It also has a narrow range of flammability, that is, in concentrations in air below about 5 percent and above about 15 percent, natural gas will not burn. The high ignition temperature and limited flammability range make accidental ignition or combustion of natural gas unlikely.
Natural gas has no known toxic or chronic physiological effects (it is not poisonous). Exposure to a moderate concentration may result in a headache or similar symptoms due to oxygen deprivation but it is likely that the smell would be detected well in advance of concentrations being high enough for this to occur.
The fact that natural gas is lighter than air further enhances its safety. Unlike other fuels such as diesel, petrol or LPG, which are heavier than air, and pools on the ground creating a fire hazard and potential pollution to waterways. Should a CNG leak occur, the gas will disperse rapidly upwards into the atmosphere and dissipate.
CNG/LNG Fuel Systems - They are "sealed," which prevents any spills or evaporative losses. Even if a leak were to occur in an NGV fuel system, the natural gas would dissipate into the atmosphere because it is lighter than air. Natural gas is not toxic or corrosive and will not contaminate ground water. Natural gas combustion produces no significant aldehydes or other air toxins, which are a concern in gasoline and some other alternative fuels.
CNG Fuel storage cylinders - They are much, much stronger than petrol tanks. The design of the cylinders is subject to a number of "severe abuse" tests such as heat and pressure extremes, gunfire, collisions and fire. The systems are also fitted with valves and other safety devices to prevent leakage and eliminate the risk of an explosion - actually making them safer than the legal requirements stipulate.
CNG Cylinder Pressure - As CNG is stored at high pressure, it is often perceived that the high pressure of the product makes it more hazardous than other fuels. While a high pressure gas leak tends to make a lot of noise as the gas is escaping. The resulting high concentrations of gas and its tendency to dissipate upwards make it less likely for the gas in the immediate vicinity of the leak to ignite.
Safe Distribution of CNG - In most circumstances, CNG is delivered via underground pipeline networks, the same networks that deliver natural gas to our homes and businesses. This method not only eliminates the need for road tankers to deliver fuel from the refinery, but also the need for ocean going oil tankers to deliver crude oil to the refinery.
The natural gas delivery system itself also has an excellent and proven safety record. According to statistics from the U.S. Department of Transportation, the natural gas transmission and distribution system is the safest way to transport.
LNG Is Not Explosive - Contrary to some misconceptions, LNG is stored at atmospheric pressure. According to the Federal Energy Regulatory Commission (FERC), “Although a large amount of energy is stored in LNG, it cannot be released rapidly enough to cause the overpressures associated with an explosion. LNG vapors (methane) mixed with air are not explosive in an unconfined environment." Should a tank ever fail and a leak result, fire is possible, but only if there is the right concentration of LNG vapor in the air and a source of ignition. This concentration is a mixture containing 5% – 15% of natural gas in the air. FERC regulations require safety zones around LNG facilities. Setback distances for onshore LNG terminals must be great enough so that flammable vapors will not reach the facilities’ property lines and radiation from a potential fire will not impact those beyond the property lines.
LNG is an odorless, non-toxic and non-corrosive liquid, and if spilled, LNG would not result in a slick. Absent an ignition source, LNG evaporates quickly and disperses, leaving no residue. There is no environmental cleanup needed for LNG spills on water.
No death or serious accident has occurred at an onshore U.S. LNG facility in 25 years. There has never been a fire, significant spill or accidental death (because of an LNG release) on an LNG ship in the history of the industry. This excellent safety record is a result of the LNG industry's stringent design and operating standards, supported by strong regulatory oversight.
