What is LNG?

Alternative Fuels / CO2-Reductions Sep. 08, 2023
What is LNG?

LNG stands for Liquified Natural Gas and is basically a cooled down natural gas which is already used for households, power generation and industrial use.

What characterises LNG?

of LNG consist primarily of methane, which is a colourless, flammable, odourless gas at ambient temperatures. To transform LNG into a liquid state, it must be cooled to around -162°C during which process impurities are removed. When liquefied, a reduction by a factor 600 of its volume will happen and unless it is heated and mixed with air, it is no longer flammable. 

LNG has approximately half the density of VLSFO, but it boasts a 20% higher calorific value. Consequently, to achieve the same energy output, a shipowner would require fuel tanks that are around twice the size of conventional tanks. In the future, LNG may be complemented and eventually replaced by e- or bio-LNG with even lower carbon emissions.

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LNG in the maritime industry

LNG carriers have been using LNG as a fuel source since the 1950s, running their engines on the natural boil-off gas coming from the cargo tanks. 

At the beginning of 2024, close to 460 LNG dual-fueled vessels are already in operation, with another 550 already on order.
LNG is widely considered to be part of the future fuel mix, first in its fossil version and overtime complemented with bio-LNG and e-LNG as a drop in.

Is LNG considered as a “green fuel”?

Life Cycle Assessment


The latest, widely recognized Life Cycle Assessment study on LNG (Sphera, 2021) reports well-to-wake emissions reductions of up to 23% in GHG emissions compared with conventional marine fuels. Furthermore, SOx, NOx and particulate matter are virtually eliminated. Constant improvement in production and consumption technologies do have the potential to further improve the LCA. 

Air Pollution


As a fuel, LNG will not produce any SOx emissions. Also, its particulate matter emissions are very low compared to conventional bunker fuels. GHG emissions are up to 20% lower than the emissions of fuel oil, and the NOx emissions of LNG are also lower.
The actual reduction in emissions would depend on the engine technology, whereas 2-stroke engines generally emit less than 4-stroke engines.

Environmental Impact


The so-called Methane slip, a small amount of methane which remains unburned and escapes from the engine into the atmosphere, is continuously reduced by the engine manufacturers to negligible levels.


FAQ about LNG

From which source is it accessible?

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LNG is becoming increasingly accessible on a global scale, with Europe, North America, and much of Asia already benefiting from an extensive and well-established distribution network. This network facilitates the large-scale transportation of LNG, meeting the growing energy demands across these regions. Looking ahead, it is anticipated that by around 2025, LNG will also be readily available in new locations such as Panama, the Middle East, and the US West Coast. 

What about safety?

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IMO adopted the IGF code for LNG and compressed natural gas, establishing a regulatory basis for LNG supply, in 2017. Using LNG for bunkering purposes is fully regulated and governed by all class societies. 
Furthermore, a possible LNG spill in the ocean is deemed to be less hazardous to the environment than a fuel oil spill. This is due to the fast dispersion of LNG making the gas evaporate quickly.  Using LNG as a bunker fuel does have risks associated with its flammability and its extremely cold liquid temperature of -162°C. However, inhalation proves less of a risk since most of the gas used onboard vessels is in a liquid state. 

How is the price comparison between LNG and fuel oil?

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The pricing of LNG is quite flexible and can be structured in different ways to suit market conditions. It can either be indexed to oil prices, which allows the price of LNG to fluctuate in line with the oil market, or it can be set at a premium above the cost of pipeline gas. This latter option often reflects the added value of LNG’s transportability and its ability to reach locations not served by pipelines. The prices of natural gas, and consequently LNG, exhibit considerable variation across different regions of the world. This regional price disparity is a direct reflection of the diverse market dynamics and the localized supply and demand factors influencing the energy sector. 

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