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Singapore currently has three filling stations for compressed natural gas in operation.
1. GPlus located on Jurong Island (restricted access).
2. GPlus and SPC at Jalan Buroh.
3. SMART Energy at Mandai Link.
SMART and GPlus plan further stations across Singapore which are supposed to be set up in the 2nd half of 2008.
In addition to the current CNG stations in Singapore, there are about 90 CNG stations in Malaysia, of which more than 10 are located in Johor Bahru. Please click on the following link to view NGV Stations in Malaysia. |
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Filling Station |
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Filling Station (opening soon) |
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cng.com.sg™ Workshops |
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Physical attributes of CNG
When refueling a CNG vehicle for the first time, one will quickly realize that the refueling process of a CNG vehicle is slightly different from refueling a petrol vehicle. The reason for that is very simple: CNG is in a gas state, not a liquid state, like petrol. A gas has different physical attributes compared to a liquid. If the cylinder is depleted and refilled with CNG, the cylinder will get warm (not hot). This is absolutely normal and there is nothing to be concerned about. If a gas is put under pressure, the density of the molecules will increase, and therefore the temperature will rise. It will take some time, until the cylinder has adopted the temperature of its environment again.
This also has a small effect on the total storage capacity of your cylinder when refueling. If a gas is heated up (the temperature increases), the pressure in the container that the gas is in increases as well. The dispensers at the filling stations automatically stop dispensing CNG, once a pressure of 200 bar is reached. If a cylinder can theoretically accommodate 18 kg CNG under standard conditions (200 bar pressure, 15° Celsius), the cylinder will carry a bit less than 18 kg. Practically this means that the cooler the cylinder and the temperature around the cylinder is, the more kg of CNG can be pumped into the cylinder.
It is absolutely no problem to leave a CNG car in the sun. This heat is never sufficient to heat up the cylinder to a critical point. The cylinders are tested and can sustain a pressure of up to 500 bar - a pressure dimension, which is usually never reached in our daily environment.
While the car is driving, a different phenomenon can be observed - the cylinder cools down. Again, this is due to the physical attributes of gases. When gas expands, the density of the molecules decreases, and the temperature drops. A nice side-effect in a warm climate like Singapore.
CNG measured in Kg
CNG is dispensed in kg (kilogram) and not in litres or m³. If one considers the above mentioned physical attributes of a gas, it becomes quickly obvious, why a measure for mass (kg) is taken instead of a measure for volume (litre or m³). One cubic metre of CNG under 10 bar pressure has just a fraction of the energy value than one cubic metre of CNG under 200 bar pressure. However, one kilogram of CNG has always the same calorific value, no matter whether it has a volume of 500 litres, or just a volume of 60 litres - under 200 bar pressure.
Depending on the size and the number of the in-built cylinder(s), the mileage of one refilling is about 150 to 300 km. |
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Chemical Composition
Natural gas consists of about 90% methane. Natural Gas, in its natural form, does not smell. Therefore, the gas is odorised prior to distribution in order to detect possible leakage. Gas can therefore be smelled already at a concentration of 0.3%. As CNG requires a concentration of about 5% to 15% to combust, 0.3% is far below the dangerous combustion level.
The image on the left shows a Methane molecule (CH4). It has a very simple construction.
Incineration is a chemical reaction. In the case of CNG, it means that Methane molecules are reacting with Oxygen.
If CNG was just Methane without any impurities, then, Methane and Oxygen would simply react to create water vapour (H2O) and Carbon-Dioxide (CO2). |
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Chemical reaction: CH4 + 2O2 --> CO2 + 2H2O
The chemical formula for the oxidation of Methane is seen above. Usually, natural gas consists of about 90% Methane, which means, there are also some other molecules included in the chemical reaction.
Please note: the images of the molecules are only apparitional. These are not the original chemical structures |
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| C3H8 (Propane) |
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| C4H10 (Butane) |
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C3H8 (Propane) and C4H10 (Butane) are the main parts of LPG. Due to their molecular structure, they are heavier than air.
Attributes of various fuel types
The table below indicates some of the attributes of different fuel types. CNG has a very high Research Octane Number (RON). Cars with fine tuned engines can optimally profit from this. The greater the octane number the greater the fuel compression ratio. Thus, there will be a higher combustion temperature in the cylinder, which leads to less wasted hydrocarbons, and therefore less pollution and wasted energy at a higher power level. This also keeps your engine cleaner as there is considerably reduced carbon build up. |
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| Fuel |
Octane |
Pressure |
| Unleaded (Normal) |
91 |
- |
| Premium (Super) |
95 |
- |
| Premium Plus (Super Plus) |
98 |
- |
| LPG |
115 |
5-15 bar |
| CNG |
120 |
200 bar |
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| 1 litre Petrol = 4 litres CNG (under 200 bar pressure) |
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