Differences Between LNG and CNG
1 Answers
LNG and CNG mainly differ in terms of their state of existence, safety hazards, volumetric energy density, and environmental friendliness. Below are the key differences between LNG and CNG: 1. State of Existence: When natural gas is cooled to approximately -162°C at 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 for storing and transporting natural gas is CNG. Due to the high pressure of compressed natural gas, it poses many safety hazards, such as a higher risk of fire. In comparison, LNG has a higher ignition point—auto-ignition temperature of about 590°C—and a narrower explosion range (5%~15%). Being lighter than air and easier to disperse, LNG offers higher safety. 3. Volumetric Energy Density: The volumetric energy density of CNG is about 26% that of gasoline, while LNG's volumetric energy density is about 72% that of gasoline, more than double that of CNG. 4. Environmental Friendliness: Natural gas must undergo strict pre-purification before liquefaction, resulting in significantly lower impurity levels in LNG compared to CNG. This makes it easier for LNG to meet stricter emission standards when used as vehicle fuel or for other combustion purposes.
