What are the differences between LNG and CNG?
2 Answers
Both are natural gases with the same main components, and the main differences are as follows: 1. State of existence: When natural gas is cooled to approximately -162°C under normal pressure, it changes from a gaseous state to a liquid state, known as liquefied natural gas (LNG). Compressed natural gas (CNG), on the other hand, is natural gas pressurized and stored in containers in a gaseous state. 2. Safety hazards: The primary method of storing and transporting natural gas is compressed natural gas (CNG). Due to the high pressure of CNG, it brings many safety hazards, such as a higher risk of fire. In comparison, liquefied natural gas (LNG) has a higher ignition point—auto-ignition temperature of about 590°C—and a narrower explosion range (5%~15%). It is lighter than air and easier to disperse, making it safer. 3. Volumetric energy density: The volumetric energy density of compressed natural gas (CNG) is about 26% that of gasoline, while the volumetric energy density of liquefied natural gas (LNG) is about 72% that of gasoline, more than double that of CNG. 4. Environmental friendliness: Natural gas must undergo strict pre-purification before liquefaction, so the impurity content in LNG is far lower than that in CNG. This creates conditions for meeting stricter standards when used as vehicle exhaust or fuel.
Let me explain the differences between LNG and CNG from a driving perspective. CNG stands for Compressed Natural Gas, stored in high-pressure tanks as a gaseous state. It's suitable for cars or taxis, with relatively lower energy density but convenient refueling since stations are widely available. LNG, or Liquefied Natural Gas, is cooled to around -162°C to become liquid, offering smaller volume and higher energy density, making it ideal for long-haul transportation with stronger endurance, especially suitable for large vehicles like trucks. In daily use, CNG systems are simpler and cheaper, with tanks easily fitted in the trunk. LNG requires specially designed insulated tanks to maintain temperature; otherwise, rapid vaporization leads to losses, and the costs are significantly higher. Both are safe options as long as you regularly inspect the pipelines and refueling equipment to ensure no gas leaks. The choice depends on vehicle type and purpose—CNG is sufficient and economical for regular commuting.
