Feature Report: Gas and LNG Transportation

5 items of content in this feature report

Going in depth

Close-up

Transportation By LNG Carrier and Regasification

Once liquefied, natural gas is loaded onto specially designed ships called LNG carriers. After its trip, the liquefied natural gas (LNG) is regasified at a dedicated terminal. In light of the growing importance of natural gas as an energy source, the LNG shipping sector is poised to play an increasing role in the global energy supply.

Transportation of LNG by carrier and  its regasification
The LNG carrier Arwa Spirit arrives in Japan with a cargo of liquefied natural gas at -162°C. © ZAMORA PHILIPPE / TOTAL

Natural gas is processed in a liquefaction trainA series of heat exchangers that gradually reduce the temperature of natural gas to -160°C... before being loaded onto purpose-built vessels for shipping to a regasification terminal (See Close-Up: "Natural Gas Liquefaction"). There are currently about 380 liquefied natural gas (lng)LNG is composed almost entirely of methane. Liquefying the gas reduces its initial volume by a factor of around 600... carriers crisscrossing the world’s oceans. These huge double-hulled, 200- to 350-meter-long ships can carry up to 260,000 cubic meters of LNG. The gas is maintained at -160°C for its journey of many thousands of kilometers.

Because natural gas is odorless, a compound is added so that leaks can be easily detected.

There are two main types of LNG carrier presently in use:

  • Carriers with insulated aluminum spherical tanks anchored to the ship's hull by a steel skirt.
  • Membrane carriers, whose tanks are part of the double hull structure.

Despite the quality of the tank insulation system, however, a certain amount of the LNG warms up and returns to a gaseous state. The boil-off rate amounts to roughly 0.15% per day. The boiled-off gas is recovered and used to powerIn physics, power is the amount of energy supplied by a system per unit time. In simpler terms, power can be viewed as energy output... the ship’s engines.

Lastly, the carriers must be operated, maintained and manned according to the highest safety standards. Crew members closely monitor temperature and pressure, check for the presence of oxygen and apply stringent tank inspection procedures. LNG carriers are built according to the most stringent standards.

An LNG carrier can transport up to 260,000 cubic meters of LNG

Arrival at the Regasification Terminal

When a carrier arrives at a receiving terminal, the LNG is offloaded and stored in large tanks at atmospheric pressure. It is subsequently pumped out of the tanks, then pressurized, heated and regasified using seawater or steam. Lastly, the gas is fed into the natural gas transmission network for delivery.

LNG has the same chemical composition as natural gas and consists primarily of methane (ch4)The main component of natural gas deposits and oil deposit gas caps. Methane is produced naturally by landfills.... It is returned to a gaseous state at the regasification terminal. Because natural gas is odorless, utilities add tetrahydrothiophene (tht) or thiolane Unpleasant-smelling gas used in very small quantities as an additive in commercial gas, which would otherwise be odorless. (THT) to give it a smell so that leaks can be easily detected.

LNG Shipping, A Promising Sector

Natural gas, the third-ranked primary energyAll energy sources that have not undergone any conversion process and remain in their natural state.. source in the world behind oil and coalCoal is ranked by its degree of transformation or maturity, increasing in carbon content from..., has averaged growth of 3% a year over the last several decades. Production is expected to increase by 50% by 2030, making it the second most widely used fossil fuelFuel is any solid, liquid or gaseous substance or material that can be combined with an oxidant... in the world.

The LNG shipping sector is set to grow in line with demand for natural gas, due to its many advantages: 

  • It is cheaper to transport gas over long distances by ship than by gas pipelinePipeline used to transport gas over a long distance, either on land or on the seabed., despite the LNG industry’s use of very expensive, high-quality materials (See Close-Up: "Transporting Gas by Land").
  • Gas pipelines can pose technical challenges (deepwater conditions) and raise geopolitical issues. Shipping bypasses these problems and connects producing countries and consumer countries more easily. Reserves located far from main consumer areas can be tapped.
  • A shipment of LNG can be diverted en route, unlike gas that is transported by pipeline. This flexibility allows consumer countries to manage their supply more efficiently and enables producing nations to unlock the full value of their resources.

Thanks to these advantages, the LNG shipping sector is set to play a promising role in the global energy supply.