The Maritime Administration (MARAD) released a comprehensive study examining the options for liquefied natural gas (LNG) bunkering and the necessary infrastructure, safety, regulatory, and training factors of each in supplying LNG to ships as a propulsion fuel in the maritime sector. Bunkering is the transfer of LNG from a supply station to a receiving vessel for the sole purpose of use as propulsion fuel.
The study examines the pros and cons of four bunkering options (truck-to-ship transfer, shore facility-to-ship transfer, ship-to-ship transfer, and transfer of portable tanks) based on factors such as the number and type of vessels to be served, local availability of LNG, port size, congestion and level of activity.
| 1. Truck-to-Ship (TTS): is the most common method used to support the LNG-fueled ship network, to date. It is the transfer of LNG from a truck’s storage tank to a vessel moored to the dock or jetty. Typically,this is undertaken by connecting a flexible hose designed for cryogenic LNG service. A typical LNG tank truck can carry 13,000 gallons of LNG and transfer a complete load in approximately one hour.2. Shore/Pipeline-to-Ship (PTS): LNG is transferred from a fixed storage tank on land through a cryogenic pipeline with a flexible end piece or hose to a vessel moored to a nearby dock or jetty. These facilities have scalable onsite storage such that designs could be capable of performing bunkering of larger volumes than TTS or with portable tanks.3. Ship-to-Ship (STS): It is the transfer of LNG from one vessel or barge, with LNG as cargo, to another vessel for use as fuel. STS offers a wide range of flexibility in location bunkering, and flexibility on quantity and transfer rate. There are two types of STS bunkering operations, one is performed at the port, and the other is carried out at sea. This has only been carried out at the Port of Stockholm for the new LNG-fueled ferry, Viking Grace.4. Portable tanks: They can be used as portable fuel storage. They can be driven or lifted on and off a vessel for refueling. The quantity transferred is flexible and dependent on the number of portable tanks transferred. A 40-foot (ISO-scale) intermodal portable tank can hold approximately 13,000 gallons of LNG |
The study also makes recommendations to regulators, port operators, vessel operators and LNG infrastructure owners on ways to address the challenges associated with widespread use of LNG as a marine propulsion fuel and provides information to help them decide which method may be most appropriate for their needs.
Ship-to-Ship Bunkering of LNG
| Advantages | Disandvantages |
| -Refueling at sea is possible; eliminates the need to come into a port- In port mobility allows for transfers to take place in protected areas or away from sensitive areas and critical infrastructure- Large transfer volumes are possible at high bunkering flow rates- Transfer rates approach shore-to-ship bunkering capabilities; exceed truck-to-ship option- Remote locations reduce/eliminate potential exposure to vulnerable targets |
– Exposes both vessels to full sea state – Currents – Wind – Waves – Higher investment and operational cost than shore and truck-to-ship options – Requires some shoreside infrastructure for loading LNG as cargo |
LNG Bunkering Threats
Although LNG is recognized as a cleaner energy source with lower NOx, SOx and particulate matter (PM) emissions, operators face challenges transporting and using LNG as fuel. Unavailability of LNG may increase the cost of LNG fuel, reducing one of the main drivers for its adoption. It is more likely that LNG will be the cheaper alternative in the short-term, for ships operating predominantly within the U.S
Deploying a robust LNG infrastructure will help ensure safe and reliable transport and use. The threats that could prevent safe and reliable bunkering operations may be categorized under infrastructure, public perception, location restrictions, policy and regulations, and natural hazards conditions
Key Findings
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Further information may be found by reading LNG Bunkering Study
Also read:
MARAD issues Total Fuel Cycle Study for LNG
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