Compressed natural gas (CNG) (methane stored at high pressure) is a fuel that can be used in place of gasoline, diesel fuel and liquefied petroleum gas (LPG). CNG is made by compressing natural gas, which is mainly composed of methane (CH4).
According to the U.S. Department of Energy’s Alternative Fuels Data Center, natural gas vehicles are actually safer than those powered by gasoline or diesel. The fact that CNG is lighter than air further enhances its safety. Fuels such as diesel, gasoline, or liquefied propane gas (LPG)/propane auto gas, which are heavier than air, pool on the ground, creating a fire hazard. If a CNG leak should occur, the gas will disperse rapidly upwards into the atmosphere and dissipate.Also, in case of a leak, if CNG’s concentration in the air is less than 5% and more than 15%, the gas will not burn even in the presence of a spark.
The answer is yes. All spark-ignited engines can be converted to CNG, but a specially designed conversion kit is required for the purpose. And after conversion to CNG the vehicle can also run on petrol or diesel (depending upon the model of the car) whenever desired simply by flicking a switch on the dashboard.
The kit costs Rs-42,500 including installation.
CNG cylinders are manufactured from a special steel alloy and are seamless in construction. Their compact size allows them to easily fit even in a small car. An empty CNG cylinder with a 60 litre-water-carrying capacity weighs 48 kg, with a length of 835 mm and a diameter of 316 mm. The 60 litre capacity cylinder is the one most regularly used; cylinders with 45 litre, 55 litre, 60 litre and 65 litre capacity are used as well.
CNG cylinders are designed and built in such a way so as to withstand high pressure. The maximum pressure in a CNG cylinder is up to 200 kg/cm2 (g) (about 2840 pounds per square inch (gauge) or psi[g] ). CNG cylinders are safe as they are manufactured as per specific requirements and tested before use, in accordance with international specifications and standards, and are duly approved by the Chief Controller of Explosives. Moreover, they are provided with a pressure relief device (PRD) that consists of a fusible plug and a burst disc that ruptures in case of inadvertent high pressure and temperature.
The bill of fuel is reduced to almost 50% on basis of averaging running of vehicle. However the cost of kit can be recovered within a year. ( The more the run of the vehicle per day, the early the cost of kit will be recovered).
CNG kit gives years of trouble-free operation. It doesn’t require frequent servicing. Just as for all other fuels, it is advised to have routine services. An authorized person should be consulted for service. As per Gas Cylinder Rules, 1981, the cylinder should undergo hydro-stretch testing every 3 years to check pressure tolerance.
Yes, a diesel vehicle can be converted to run on CNG, but the conversion cost is higher than the conversion of petrol vehicles.
“Absolutely yes. Gas tanks are designed, made and certified according to the highest industry standards”, these gas tanks “are equipped with a safety valve, and in the unlikely event of a fire, would release the gas to the outside air in a controlled manner, preventing anything from happening to the vehicle”. In addition, the components have been tested to endure “extreme conditions: the tank reaches a maximum pressure of about 200 bars, but it is designed to withstand more than twice as much”. Furthermore, the myth that gas can freeze under conditions of use is “impossible” because “in order for natural gas to liquefy, the outside temperature would have to be colder than 160 degrees below zero”.
CNG is an environment-friendly fuel. The natural gas is mainly composed of methane and its exhaust emissions consist of water vapor and a negligible fraction of carbon monoxide. The absence of carbon and other particulates result in negligible amount of harmful elements in exhaust fumes.