Compressed Natural Gas (CNG)

Compressed Natural Gas (CNG) is primarily composed of methane and, due to producing less pollution compared to other fossil fuels such as gasoline and diesel, is considered one of the cleanest and most environmentally friendly fuels.

CNG is lighter than air, and in case of leakage, it disperses quickly into the atmosphere. This characteristic, along with its ability to mix easily with air, makes it a suitable option for cars and heavy vehicles such as buses. In addition, because of its cost-effectiveness and the possibility of being distributed through gas supply networks, its use is very common in countries such as Iran. With around 4 million dual-fuel vehicles, Iran has the largest CNG fleet in the world.

سوخت CNG
جایگاه CNG

Because CNG is in a gaseous phase, it can only be stored in high-pressure tanks (about 200 to 250 bar). For this reason, dual-fuel vehicles require large cylinders that usually occupy the trunk space. To address this issue, some automakers produce dedicated vehicles powered exclusively by CNG.

CNG is sometimes mistaken for LNG (Liquefied Natural Gas). The main difference between the two lies in their storage methods:

CNG is stored at ambient temperature under high pressure, while LNG is stored in liquid form at very low temperatures and under atmospheric pressure. LNG takes up less space, but requires costly cooling equipment. Typically, for long distances or in areas where pipelines are not available, natural gas is first converted into LNG, then transported by ship or train, and finally converted back into gas (CNG) at the destination.

CNG can be compared with liquefied petroleum gas (LPG) in terms of vehicle applications:

  • Safety: CNG is less flammable and therefore safer; however, the need for high-pressure tanks increases the cost of building refueling stations.

  • Leak detection: LPG is heavier than air and has an odor, making leaks easy to detect. In contrast, CNG is odorless and disperses quickly in the air, which makes leak detection more difficult.

  • Economy and efficiency: CNG is cheaper than LPG, but vehicles generally achieve a longer driving range with one tank of LPG compared to CNG.

CNG