CNG - Myth or Facts?

Over the past two months the cost of petrol has dropped over ten times with a decremental 5 cents dropped on the pump each  time. However the cost of petrol is still considerably high and the dropped since to be a momentarily respite only. Much to the disappointment of many government across the world, the OPEC met up on 24 Oct 08 and announced that they will be slashing the oil output to stop the declining of the dollar per barrel cost. With the expected rising costs of petrol coupled with the economic meltdown and the increasing awareness in climate change, many vehicle owners are now looking into alternatives with which they can replace petrol with. Compressed Natural Gas (CNG) appears to be a viable alternative which promises to save cost, less polluting to the environment and can be easily retrofitted into existing vehicles. However many drivers are still concerns on safety and efficiency of the vehicle once it is converted to CNG. 

Saving GAIA - Doing your Part. 

Natural gas requires little processing before use (unlike gasoline which requires the refinery process). Chemically, natural gas contains about 90% methane with smaller amounts of ethane, propane, butane, carbon dioxide and other trace gases. The high methane gives natural gas a high octane rating  of 120 - 130. Though methane itself is a greenhouse gas, it has clean burning characteristics, allowing high efficiency and low emissions. According to ConsumerReports.org, natural gas burns cleaner than gasoline. Compared to gasoline burning it reduces carbon monoxide by 90 - 97%, nitrogen oxide by 35 to 60% and non-methane hydrocarbon emissions by 50 - 75%. Though not a renewable resource, natural gas is plentiful in supply with the current world reserves point to another 60 years of supply.

How Safe is CNG

The thought of driving around the streets with a huge tank sitting at the back of the seat  burning your engine off and propelling it ahead makes many stomach turned. There have been many articles depicting tales of how a car installed with CNG gas tank exploded after being involved in a traffic accident. However safety experts and promoters of CNG conversion rallied and claimed that the safety of CNG vehicles is on par or higher than that of petrol. The pressurized tank is built to withstand severe impact, temperature and environment exposure. As CNG is lighter than air, it will evaporate quickly due to limited flammability into the atmosphere when there is a leak instead of collecting as a puddle under the car like petrol would. It will not burn at concentrations below 5% or above about 15% when mixed with air. Gasoline and diesel burns at much lower concentrations and ignite at lower temperatures. 

Performance

I doubt anyone would want to but an Evo 10 or any other performance vehicle and have it converted to CNG to only compromise on the performance of the vehicle. Many drivers have reported up to 15% power loss when compared to gasoline as unlike the gasoline system which delivers full power until empty, CNG vehicles typically achieved similar power to gasoline when the CNG tank is under the full pressure of 3000psi. However when the pressure drops to 300-400 psi you may have difficulty going up the hills no matter how powerful your car is. When power is required there is always the option of switching back to patrol at the flick of a switch, so this may not be a real problem. Though the CNG tank is larger than regular gasoline tank, you get fewer miles per liter because the CNG tank is considered empty when pressure drops below a low limit. Hence it actually carries less usable fuel per volume of tank. You may experience a mileage loss per full tank of 35% as compared to regular gasoline. For those who treasure the trunk space and stores half of your wardrobe and assortment of battle hardened golf set, another disadvantage that you should be aware of is that you will typically have half the trunk space because of the space taken by the CNG cylinder. For cars with smaller trunk space, you may say goodbye to it. 

Cost Savings

At the end of every argument and debate the cost savings will be the biggest motivational reasons for anyone to make the change. What kind of cost savings can you expect from you conversion to CNG? The conversion itself may set you back around SGD $ 1300 for a carburetor car and about SGD $ 3000 for a fuel-injection car. However with the volume of CNG conversion currently on the rise, economics of scale may push this price down a little. To fuel a 1.5 litre car to drive 200 kilometres, it will cost about S$11.50 using CNG, based on the current pump price, compared to S$34.20 before discount if a 95 Octane petrol is used. 

With a saving of S$22.70, the real question should be how much time and effort is one truly prepared to spend to go green?

The Nitty Gritty Stuff

For those who are already making the consideration to migrate into CNG as a sign of protest against OPEC for their knee jerking decision in increasing the petrol prices do read on before making your decision. 

• The CNG cylinder that you need to install in your trunk is huge, typically larger than the standard gas cylinder that you use for cooking at home. There are also several sizes of the CNG cylinder available. Just remember smaller tank equals less range for your vehicle when running on CNG. But it also means more trunk space.
• Some people have reported that acceleration of their vehicle using CNG may not be as good as when running on gasoline and you have to floor the pedal more. However for typical city traffic, this will not be a problem.
• You need to plan on when to refuel your CNG as during peak hours there can be a long queue and there is a dearth in the CNG refilling stations in this country at this moment.

CNG may be cheaper vis-a-vis petrol or diesel but as demand increases who knows? The greed factor in the CNG supply chain's owners may affect the increase of CNG's retail price. That would mean that the time to recoup you investment in the CNG conversion would be pushed out further into the future. There advantages and disadvantages of CNG powered vehicles and the facts have been laid out. The next move belongs to you. For me I am contented with the way my car is now.