Okay, so everyone wants to save a bit of money. And why not? All you have to do is invest a few thousand rupees and Bob�s your uncle. Right? Indeed, but there area a few strings attached worth paying attention to.
The concept of fitting CNG kits in cars has gained countrywide acceptance with the main attraction being the savings that result. CNG simply stands for compressed natural gas. It really is no different from the gas we get in our industries or homes to burn for whatever purpose we wish to.
Compared to conventional liquid fuels, CNG has the advantage of being �greener�, that is, it is less polluting and damaging to the environment than either petrol or diesel. In fact, some researchers even claim it to be virtually non-toxic. This is the prime reason for its acceptance worldwide. However, in Pakistan it is preferred primarily for its cost savings.
Locally manufactured cars that run on petrol average between 7-14 kilometers per liter with the accepted average figure being 10kms per liter. With the cost of a liter of petrol crossing the Rs50 mark, it costs on an average Rs5 to drive one�s car for every kilometer. Comparing this with CNG, filling a tank of CNG costs approximately Rs250. Any car with reasonable fuel efficiency will travel 120kms before the tank gets empty. Hence, the cost to drive one�s car for a kilometer on CNG is about Rs2 (60 per cent less than petrol).
For an average run of 15,000kms for a car, the owner will save almost Rs45,000 per year on his/her fuel bill. Considering that the kit itself costs Rs30,000, this saving is substantial and attractive by any standard.
But have we ever wondered whey we don�t see westerners driving their cars on CNG? After all, Americans for instance drive their cars more and for longer distances than any other nation in the world.
It is true that CNG has its pros and cons and leaves the car owner smiling at the end of the day. But it has its own share of cons, which make this fuel unattractive to drivers worldwide, particularly in those regions where liquid fuels are cheap, such as in the Middle East or the US.
To begin with, any driver who is used to liquid fuel will testify that gas does not provide the same driving pleasure as liquid fuels. This is because petrol and diesel are denser and are more packed with energy. Thus, an engine designed for liquid fuels will not be able to generate the same amount of power when running on gas as it would when running on liquid fuel. This causes the engine to run faster to meet the car�s energy requirements, resulting in higher wear for the engine per kilometre of travel and shorter engine life.
Furthermore, a car running on CNG travels for significantly less distance between refueling than a car running on petrol, since there is a limit to how big the storage for gas can be made. It results in more frequent refueling stops and in places where CNG filling stations are in short supply the queues to get one�s car refueled can be painfully long.
CNG tanks are heavy and carrying them in one�s boot all the time exerts a concentrated load on the rear suspension of the car. Small cars and hatchbacks fitted with CNG are known to have perpetual suspension problems, often resulting in higher maintenance of the car. Since the boot of the car is occupied by the tank, there is often no or very little space for luggage left in the car.
Transporting gas, due to its light nature, can be expensive and sometimes even unfeasible. Hence, as one travels away from urban centers, availability of gas becomes limited. An owner of a CNG station will also tell you that setting up a CNG station is more expensive than a petrol station.
And finally, there is the most important issue of safety. CNG tanks are pressurized vessels, filled with highly inflammable gas, which can leak even from the smallest of cavities. Naked flames, such as those from cigarette lighters can cause havoc for passengers. Furthermore, any impact with the tank, such as those from accidents, can cause the tank to leak or even explode.
No matter how good the material and fabricator of the tank are there will be some inherent cracks in the tank, which are too small to see. By continuously filling and emptying the tank, these cracks widen, making them more susceptible to leakage and explosion. In application where pressure vessels are used, such as oxygen tanks for deep sea divers, the tanks are periodically inspected to ensure that there are no cracks large enough to be life-threatening. Since most of the CNG tanks in Pakistan are less than five years old, this problem has not been encountered so far. However, as the tanks age, the cracks will begin to widen and accidents will become inevitable.
To avoid mishaps in the future, every vehicle fitted with a CNG tank should be subjected to annual or bi-annual check-up. Also, a certificate should be issued for the vehicle certifying that the vehicle is road-worthy. The scheme, however, can only be implemented if the government takes interest in it.
Nowhere-it simply changes into other substances. That is what burning does to everything.
