Liquefied natural gas (LNG) has more or less the same composition as natural gas used for homes and power generation, and in industry. Its main component is methane (CH4), the hydrocarbon fuel with the lowest carbon content.


The main component of liquefied natural gas (LNG) is methane (CH4), the hydrocarbon fuel with the lowest carbon content and, therefore, with the greatest potential for reducing CO2 emissions (maximum reduction: approximately 26% in compared to HFO). LNG has more or less the same composition as natural gas used in homes, for power generation, and by industry. The LNG production process ensures that it is virtually sulfur free. Therefore, the use of LNG as fuel does not produce any SOx emissions. Since the boiling point of LNG is approximately -163 ° C at 1 bar absolute pressure, LNG must be stored in insulated tanks.

The energy density per mass (LHV in MJ / kg) is approximately 18% greater than that of HFO, but the bulk density is only 43% of HFO (kg / m³). This results in about twice the volume compared to the same energy stored in the form of HFO. Taking into account space requirements related to shape, cylindrical LNG tanks typically occupy three times the volume of an equivalent amount of energy stored in the form of fuel.

The prices of natural gas centers around the world (except in certain parts of East Asia) have been below the price of crude oil and HFO for the last ten years. The delivery price of LNG fuel to vessels must also take into account the cost of liquefaction or cargo breakdown, distribution cost, and applicable profit margins. Compared to other alternative fuels, LNG appears to have achieved the most competitive feedstock price level historically among all alternative fuels. Currently, the price level is competitive with MGO, but direct competition with HFO can be difficult: how it is shown in the Compared graph of fuel prices.

Since 2020, high sulfur HFO is not allowed without a scrubbing system installed, and the price of the new VLSFO reference fuel is higher than that of HFO. LNG also has the potential to compete with high sulfur HFO and scrubbers.


Although still limited, the LNG supply infrastructure for ships is improving rapidly. A large part of the supply of LNG as well as the distribution of LNG to the supply points is still carried out by road. Bunker vessels are being developed for other key locations such as the western Mediterranean, the Gulf of Mexico, the Middle East, Singapore, China, South Korea and Japan, and are likely to materialize in parallel with significant orders for offshore vessels. using LNG in the coming years. LNG fleet map and supply vessels.

For information on the LNG supply infrastructure in Spain, see the supply and demand maps , which offer detailed and continuously updated information on all existing or developing LNG supply points and their demand in Spanish ports. In principle, LNG is available throughout the world (import and export terminals), and investments are being made in many places to make LNG available to ships. Truck fueling and local permanent warehouses will also continue to grow for certain trades and segments. Dual fuel engine technology can also offer some flexibility and redundancy as the LNG supply network for the offshore fleet evolves.

The IMO IGF Code for LNG and CNG entered into force on January 1, 2017, establishing an international regulatory basis for the design and construction of LNG ships.

Other aspects, such as the fueling of LNG ships, are subject to national regulations and therefore must be evaluated on a case-by-case basis. For example, only a limited number of ports have established local regulations for the supply of LNG. In addition, SGMF, IACS and ISO have also developed some requirements and guidelines for the supply of LNG.

For the foreseeable future, there are no major limitations to production capacities that could limit the availability of LNG as fuel for ships. LNG has a share of approximately 10% in the global natural gas market. LNG production capacity is expected to increase considerably in the next five years. In 2016, the global LNG production capacity was approximately 320 mt / y. This figure will increase by almost 40% to reach around 450 mt / y in 2020 (World LNG Report 2017; International Gas Union [IGU]).

Natural gas from LNG is the cleanest fossil fuel available today. There are no SOx emissions related to it, the particulate emissions are very low, the NOx emissions are lower than those of MGO or HFO, and other emissions such as HC, CO or formaldehyde from gas engines are low and can be mitigated by exhaust gas post-treatment if necessary. However, the release of methane (mehtan slip) must be considered when evaluating the CO2 reduction potential of LNG as a fuel for ships (the maximum value is approximately 26% compared to HFO). Low-pressure Otto cycle gas engines that burn LNG meet the IMO Tier III NOx limit without the need for exhaust gas treatment.

Gas engines, gas turbines, and LNG storage and processing systems have been available to onshore facilities for decades. The maritime transport of LNG by ship also has a history that dates back to the middle of the last century. Developments to use LNG fuel in general shipping started at the beginning of the current century. Today, the technology required to use LNG as a fuel for shipping is readily available. Gas turbine and piston engines, various types of LNG storage tanks as well as process equipment are also commercially available.

LNG as a fuel for ships is rapidly approaching the status of a fully developed technology, with several technology providers active in the market. As applications increase and competition between vendors heats up, we can observe CAPEX decreasing. CAPEX costs for LNG systems are and will continue to be higher than the expenses associated with using an HFO scrubbing system.

The OPEX costs of LNG systems on board ships are comparable to the operational costs of petroleum fuel systems without scrubbing technology or an SCR. Gas engine systems have approximately the same efficiency as conventional fuel systems. For this reason, the energy consumption of an LNG ship is approximately the same as that of an oil ship. Maintaining a gas engine can be less expensive thanks to cleaner fuel. Currently, the maintenance intervals for conventional and gas engines are often the same, but with more operating experience to draw on, they can be extended for gas engines. The costs of maintaining the high-pressure gas supply system on board ships with high-pressure engines should be considered.


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