The distinction between compressed natural gas (CNG) and liquefied natural gas (LNG) may be unclear to some. Both are cleaner alternatives to traditional fuels such as gasoline and diesel, derived from natural gas.
Despite sharing the same source, CNG and LNG are handled, stored, and used differently. Let’s look at six simple differences between CNG and LNG.
Form and Storage
One of the biggest differences between CNG and LNG is how they are stored and what form they take.
- CNG is natural gas compressed and stored in high-pressure containers at around 3,600 psi (pounds per square inch). It remains in gaseous form and requires large, heavy tanks to confine it.
- LNG, on the other hand, is natural gas that has been chilled to an extremely low temperature, around -162°C (-260°F). This cooling procedure converts it to a liquid, which is subsequently stored in properly insulated tanks under considerably lower pressure.
In short, CNG stays as a gas under high pressure, while LNG is turned into a liquid by freezing it.
Energy Density
Another key difference is how much energy each fuel can store in a given amount of space.
- Because CNG is still in gas form, it contains less energy, requiring more room to store the same amount of energy.
- LNG, as a liquid, is more denser in terms of energy. It stores a lot more energy in a smaller space, making it better suited for transferring huge volumes of fuel.
Consider this: LNG is equivalent to fitting more gasoline into a smaller luggage, whereas CNG requires a larger suitcase to deliver the same amount of energy.
Uses
CNG and LNG are used for different kinds of vehicles and purposes.
- CNG is most often used in vehicles that drive short distances, like city buses, taxis, and everyday cars. It’s convenient for local driving because it’s easier to store and refill.
- LNG is more appropriate for long-distance transportation, such as big trucks, ships, or trains. Because LNG can transport more energy in less space, it is ideal for vehicles that must drive long distances without stopping frequently to refill.
So, if you’re taking a short journey around town, CNG may be a better option. However, if you are transporting items across the country, LNG is more efficient.
Refueling and Infrastructure
Refueling a vehicle with CNG or LNG requires different equipment and stations.
- CNG refueling is generally easier and more common, especially in cities. There are numerous stations equipped with compressors that can swiftly fill CNG tanks under pressure.
- However, LNG refueling necessitates the use of specialized equipment to handle the extremely low temperatures required to keep the gas liquid. As a result, LNG refueling facilities are less common and require more sophisticated infrastructure.
In a nutshell, CNG refueling is more simple and accessible than LNG refueling, which is more complex and uncommon.
Safety and Environmental Impact
Both CNG and LNG are regarded safer and more environmentally friendly than traditional fossil fuels, although their safety factors differ.
- If there is a leak, CNG is less likely to contaminate the ground because it disperses fast into the air. However, because it is held under tremendous pressure, there is always the possibility of an explosion if the tank is destroyed.
- LNG is safer to transport because if it spills, it rapidly evaporates into the atmosphere as gas. However, if LNG warms up too much during storage, it can expand back into gas, causing dangerous pressure in enclosed places.
Both fuels are cleaner for the environment than gasoline or diesel, but each has unique safety concerns when handled or transported.
Cost and Availability
Finally, CNG and LNG differ in terms of their availability and affordability.
- CNG is typically less expensive and more readily available in most cities. There is already a well-established network of CNG refilling stations around the world.
- LNG, which provides more energy in a smaller space, might be more expensive due to the complex cooling and storage procedure. LNG refueling infrastructure is also less prevalent than CNG, making it more difficult to access.
In layman’s words, CNG is more economical and generally available, but LNG may be more expensive but delivers superior energy efficiency for long-distance transportation.