Application of LNG powered ships -- Introduction to LNG filling mode

With the development of technology, the safety problem of LNG powered ships has been constantly overcome. Recently, the use cost and convenience of LNG have gradually become an important obstacle that must be broken through in the application of LNG powered ships. Ship LNG filling is a key point of the above problems.

Ship LNG bunkering is actually an operation to transfer LNG fuel from the supply source to the LNG powered ship. According to the supply source, we can divide ship LNG filling into three modes: truck to ship -- TTS, ship to ship -- STS, and port to ship -- PTS.

01   Car to ship

In the vehicle to ship mode, the LNG refueling truck is usually connected to the receiving ship on the wharf with flexible hoses. The filling volume is about 50-100 m3, and the filling speed is about 40-60 m3/h.

Advantages: flexible operation; Infrastructure requirements are not high; The delivery volume (number of trucks) can be adjusted according to different customer needs; It can adapt to different safety requirements; It can provide services for different LNG fuel users.

Disadvantages: limited truck capacity; Limited flow (the rate can be increased by sharing the main pipe); Significant impact on other operations involving passengers and/or goods; Limited movement on the side of the dock; Mainly affected by the existence of refueling vehicles; Roadside restrictions (permits, physical restrictions, traffic restrictions, etc.).

02   Ship to ship

In the ship to ship (STS) mode, LNG is transported by another ship or barge to the receiving ship. The filling volume is about 100-6500 m3, and the filling speed is about 500-1000 m3/h.

Advantages: It usually does not interfere with cargo/passenger operations, and can achieve synchronous operation (SIMOPS); It is the most adaptable LNG filling mode, especially for ships with short port turnover time; The delivery volume is larger and the efficiency is higher than that of the vehicle to ship (TTS) method; It is flexible in operation and can be refueled when the receiving ship is berthed, anchored or in other circumstances.

Disadvantages: The initial investment cost is high, involving the design, construction and operation of LNG fuel tankers/barges; LNG bunkering business has a significant impact on the life cycle cost of LNG bunkering ships; The size of bunkering ships is limited by the port.

03   Port to ship

In the port to ship (PTS) mode, LNG can be directly filled from small LNG fuel storage units (LNG tanks), small filling stations or LNG import and export terminals. The filling volume is about 500-20000m3, and the filling speed can reach about 1000-2000m3/h.

Advantages: faster delivery and more quantity; It is a good choice for ports with long-term filling demand.

Disadvantages: It may be difficult for LNG receiving ships to berth at the filling dock; It is difficult to ensure the availability of large LNG terminals; Unless there is a pre-determined contract, it is difficult to estimate the LNG available for filling in small tanks.

There are also some special modes, such as the LNG tank (ISO LNG tank) as a container and the whole as a fuel tank. Each of these modes has its advantages and disadvantages, which can be applied according to the development of the port itself. Taking Yangshan Port as an example, the existence of existing LNG terminals and tanks is a good start for LNG filling. As a diversified port, Yangshan Port also provides different application scenarios for ship LNG bunkering.

The small LNG powered ships berthed at Shenjiawan Passenger Terminal and the future north wharf of Yangshan can be the application objects of the car to ship mode; Shengang Oil Terminal and Phase I to IV Container Terminals can choose ship to ship refueling mode; The future Yangshan North Terminal and the future LNG Phase II Terminal are likely to be built into a model of port to ship mode. The LNG tank mode will also have a place in the future at the wharf on the north side of Yangshan.

The main factors affecting the selection of ship LNG filling mode are market competition and policy planning. There are many unstable factors in the development of ship LNG bunkering, which need the coordination and cooperation of relevant parties and the foresight of decision-makers. In the process of LNG bunkering, the responsibilities and coordination between the ship owners, LNG suppliers, ports, security personnel, competent departments and decision-makers, as well as related parties, need to be finally established through regulations, standards and relevant guidelines. At the initial stage of LNG bunkering development, a reasonable and perfect LNG bunkering specification system will contribute to the healthy and orderly development of ship LNG bunkering operations. Next, we will introduce the international LNG bunkering regulatory framework.

Editor of this issue: You Changhui

Source: Yangshan Port Maritime Bureau