LNG Shipping: The Basics of Liquefied Natural Gas Transportation

Transportation of LNG is growing in popularity as a cleaner and less polluting energy source. It can be transported by trucks or specialized vessels called LNG carriers.

What is Liquefied Natural Gas?

Liquefied Natural Gas (LNG) is a form of natural gas that has been cooled down to a liquid state for easier storage and transportation.

Why is LNG easier to transport?

One of the main reasons is that LNG has been cooled down to a liquid state, which reduces its volume by around 600 times. This means that more LNG can be transported in a single vessel or container, making it more efficient and cost-effective.

Furthermore, the process of liquefaction removes impurities such as water, carbon dioxide, and sulfur compounds from the natural gas. This results in a cleaner and purer form of energy that is less corrosive and easier to handle during transportation.

The reduced volume and purity of LNG also make it safer to transport. Because LNG is a liquid, it does not expand or contract significantly with temperature changes, reducing the risk of explosions or leaks.

How do you transport liquefied natural gas?


Smaller quantities of LNG can be transported by truck. Cryogenic tanks are used to transport LNG by truck, maintaining the extremely low temperatures required to keep LNG in its liquid state.

Truck transportation provides a flexible and efficient method of delivery, particularly for areas without access to pipelines or where other modes of transportation are impractical.

LNG Carrier

large-scale transportation uses specialized vessels known as LNG carriers. These carriers are designed to handle the unique properties of LNG, with advanced insulation systems to maintain the extremely low temperatures required for storage.

LNG carriers are typically double-hulled to prevent leaks and spills, and equipped with sophisticated monitoring systems to ensure the safety and integrity of the cargo.

During transportation, LNG carriers are loaded and unloaded at dedicated terminals equipped with specialized infrastructure, including storage tanks and loading facilities. Once the LNG reaches its destination, it is regasified and injected into the natural gas pipeline network for distribution.

What pressure is LNG tranported at?

LNG is transported at relatively low pressure, typically around 3-5 bar (43-72 psi). This is significantly lower than the pressure at which natural gas is transported through pipelines, which can be as high as 70-100 bar (1000-1450 psi).

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Are LNG tankers refrigerated?

LNG tankers are indeed refrigerated in order to keep the liquefied natural gas at its extremely low temperatures. The cooling process is essential for maintaining the LNG in its liquid state throughout transportation.

How is LNG loaded onto ships?

Loading liquefied natural gas (LNG) onto ships involves a carefully coordinated process to ensure the safe and efficient transportation of this valuable energy source.

Here are the steps involved:

1. Preparing the LNG carrier: Before loading can begin, the LNG carrier must be inspected and prepared for the transfer. This includes checking the vessel’s integrity, verifying that safety systems are functioning properly, and ensuring that all necessary equipment is in place.

2. Connecting the loading arms: At the loading terminal, the LNG carrier is connected to loading arms that transfer the LNG from storage tanks to the ship’s tanks. These loading arms are flexible and can move in multiple directions to accommodate the movement of the ship during loading.

3. Transferring the LNG: The LNG is transferred from the storage tanks to the ship’s tanks using a cryogenic pump system. This system carefully controls the flow and pressure to prevent any leaks or spills.

4. Monitoring the transfer: During the loading process, the LNG is continuously monitored to ensure that the tanks do not exceed their maximum capacity. The temperature, pressure, and volume are carefully regulated to maintain the stability and safety of the cargo.

5. Disconnecting the loading arms: Once the LNG loading is complete, the loading arms are disconnected, and the LNG carrier is ready to set sail.

How long does it take to load an LNG ship?

The time it takes to load an LNG ship can vary depending on several factors, including the size of the ship, the volume of LNG being loaded, and the specific loading procedures at the terminal.

On average, it can take anywhere from a few hours to a couple of days to load an LNG ship.

How is LNG kept cold on ships?

Insulation system

To keep LNG cold on ships, advanced insulation systems are used. These insulation systems are designed to minimize heat transfer and maintain the low temperatures required for LNG storage.

The insulation materials used, such as foam or reflective coatings, provide a barrier against heat penetration, keeping the LNG chilled.

Onboard refrigeration systems

LNG carriers are equipped with onboard refrigeration systems. These systems continuously cool the cargo tanks, ensuring that the LNG remains at the optimal temperature throughout the journey.

Temperature sensors and control systems are used to monitor and adjust the cooling process, maintaining the desired conditions for the LNG.

Re-liquefaction systems

Some LNG carriers utilize boil-off gas re-liquefaction systems. These systems capture the natural boil-off gas that occurs during transportation and re-liquefy it, returning it back to the cargo tanks.

By re-liquefying the boil-off gas, the temperature inside the tanks is lowered, helping to keep the LNG cold.

How much LNG can one ship transport?

The size of the ship determines the amount of LNG it can carry. Typically, these vessels range in size from small-scale carriers with a capacity of around 30,000 cubic meters to large-scale tankers that can transport over 200,000 cubic meters of LNG.

To put this into perspective, a single large-scale LNG tanker can hold the equivalent of about 140 Olympic swimming pools! This massive volume of LNG allows for efficient and cost-effective transportation over long distances, making it possible to deliver LNG to countries around the world.

Why is LNG not a viable fuel for vehicles?

Firstly, the infrastructure for LNG refueling stations is still limited compared to traditional gasoline or diesel stations. This lack of accessibility makes it difficult for drivers to find convenient locations to refuel their LNG-powered vehicles.

Additionally, the cost of converting vehicles to run on LNG can be quite expensive. Retrofitting existing vehicles or purchasing new LNG-powered vehicles can be cost-prohibitive for many individuals and businesses.

Furthermore, LNG-powered vehicles typically require larger fuel tanks due to the lower energy density of LNG compared to gasoline or diesel. This can limit the cargo space or passenger capacity of the vehicles, making them less practical for certain applications.


Liquefied petroleum gas (LPG) is a mixture of hydrocarbon gases, primarily propane and butane, that are compressed and stored as a liquid.

liquefied natural gas (LNG) is a form of natural gas that has been cooled down to a liquid state for easier storage and transportation.


LPG is a mixture of hydrocarbon gases, while LNG is primarily composed of methane. This difference affects their energy content, with LNG having a higher energy content per unit volume compared to LPG.

Storage temperature and pressure

LPG is typically stored at a higher pressure and a relatively higher temperature compared to LNG. This allows LPG to remain in its liquid state at ambient temperature, while LNG requires extremely low temperatures to maintain its liquid form.

Uses and applications

LPG is commonly used for residential and commercial purposes, such as heating and cooking, as well as for fueling vehicles. LNG, on the other hand, is primarily used for large-scale applications, such as power generation and industrial processes, as well as for long-distance transportation.

Is LNG more expensive than natural gas?

Yes, LNG can be more expensive than traditional natural gas for several reasons. While LNG offers numerous advantages as a cleaner-burning fuel source, it comes with additional costs compared to natural gas.

One reason is the process of converting natural gas into LNG, which involves a complex liquefaction process that requires specialized equipment and infrastructure. This adds extra costs to the production of LNG, impacting its price.

Transportation costs also contribute to the higher price of LNG. Specialized vessels and infrastructure, as well as the energy required to maintain the low temperatures of LNG during transportation, can contribute to higher costs.

Infrastructure investment is another factor. To support the transportation and use of LNG, significant investment is required for liquefaction plants, regasification terminals, and storage facilities. These investments are necessary for the safe and efficient movement of LNG, but they add to the overall cost.