Some vehicles are labeled with LNG , while others are labeled with CNG . Both LNG and CNG are methods of storing natural gas. So, although both use natural gas, what are the differences between LNG and CNG?
Firstly, both LNG and CNG vehicles run on natural gas as fuel and are considered clean energy vehicles. The main component of the fuel is methane, and they are very similar in terms of physical and chemical properties, fuel economy, and calorific value. The exhaust emissions from both vehicles generally do not contain sulfur compounds or particulate matter.
However, there are differences—mainly in their forms:
CNG stands for Compressed Natural Gas, which means it is stored as high-pressure gaseous natural gas. CNG vehicles use this high-pressure gas as fuel.
LNG stands for Liquefied Natural Gas, meaning it is stored as low-temperature, atmospheric pressure liquid natural gas. The volume of LNG is approximately 1/625 of the same amount of gaseous natural gas, and its mass is about 45% of the same volume of water.
Therefore, the storage efficiency of LNG is 2.5 times higher than that of CNG. This is why heavy-duty trucks and large buses usually require only one or two tanks, while CNG typically requires 8 to 12 tanks to achieve the same range.
For example: A 12-cylinder LNG tractor has 8 CNG-2 cylinders of 205 liters each (Type 2 CNG wrapped steel cylinders) and 4 CNG-2 cylinders of 140 liters, with a total volume of 2200 liters or about 440 cubic meters. Its range is about 800 kilometers.
In comparison, an LNG tractor may use a single 850-liter tank or two 450-liter tanks, with a total load of around 311 kg and about 450 cubic meters of gas.
