Client Corner: What does it take to build an LNG bunkering ship?

What is an LNG bunkering ship?

A liquefied natural gas (LNG) bunkering ship is a vessel that delivers LNG to gas-fueled ships. Outfitted with highly sophisticated onboard equipment – including a cargo containment system, boil-off gas handling systems and LNG transfer systems – bunkering vessels are ideal for transporting and transferring cryogenic LNG. Bunkering ships may also crucially support gas-fueled ships, supplying inert gas, retrieving boil-off gas and providing LNG recovery in case of emergency.

Bunkering vessels account for 1.5% of the global LNG carrier fleet, and have an average tank capacity of 5,000-8,000 m³. Bunkering ships are generally tailor-made for their area of operation and intended clients, designed to meet the needs of nearby gas-fueled ships, LNG terminals and port infrastructure.

What equipment is needed to build an LNG bunkering ship?

Three pieces of equipment are at the heart of an LNG bunkering vessel: the cargo containment system (CCS), boil-off gas handling system, and LNG transfer system.

CCS provide high-performance insulation, ensuring LNG remains in its liquid state, at a minimum temperature of approximately -160° C.

Advanced boil-off gas handling systems can be installed to help manage LNG vapors through subcooling and reliquefaction, maintaining optimal levels of temperature and pressure inside the CCS.

The LNG transfer system enables LNG delivery to gas-fueled ships, vapor return, and onboard reliquefaction and utilization of vapor return. Together, these three systems ensure that a maximum amount of LNG can be safely and efficiently delivered.

Bunkering ships are also equipped with dual-fuel or gas-only engines powered by boil-off gas, and may be driven by mechanical or electrical propellers. Depending on the size of the vessel, bunkering ships may have transversal thrusters, azimuthal thrusters or other maneuverability devices installed onboard. 

How much does an LNG bunkering ship cost?

Building an LNG bunkering ship with a standard cargo capacity of 7,500 m³ costs about $50 million USD. This is already far less than the initial CAPEX figure for the earliest bunkering ships (~$60 million USD), thanks to increased competition among shipyards and equipment manufacturers.

A significant portion of the cost comes from the cryogenic equipment onboard, which is typically made from steel alloys with high nickel content. Solutions that use alternative, less expensive materials are under development (e.g., a high manganese-based steel) and may contribute to further lowering CAPEX.

Do LNG bunkering ships need a dynamic positioning (DP) system?

No. A DP system is not a requirement for bunkering vessels.

However, having one can be a big advantage, as DP systems increase station keeping. This is key for bunkering vessels that are not moored to gas-fueled ships during operation, which must otherwise manually maintain their position. DP systems enable bunkering vessels to remain steady, delivering LNG safely, smoothly and efficiently, while maintaining distance from gas-fueled ships.

Photo credit: MOL