The truck-to-ship transfer (TTS) is at present the most frequently used bunker configuration but in several ports ship-to-ship (STS) bunker configurations are under development. The choice for TTS was driven by the difficulty of developing the business case for bunkering by special barges and from the shore. However, the business case is not the only decisive criterion for selection of the preferred bunkering method. Also the operational flexibility, safety requirements and capacity will be taken into account in the future.
LNG is currently available as a bunker fuel for maritime and inland shipping at ports worldwide. To explore the LNG bunker infrastructure for your regions of interest, the LNG bunker navigator of Sea\LNG could be used.
Truck to Ship
Among the various methods for in-port bunkering of LNG-fuelled ships, Truck-to-Ship (TTS) transfer is currently most frequently used. With TTS, the LNG truck is connected to the ship on the quayside, generally using a flexible hose. This is today the most widely used bunkering method, because of the still limited demand in combination with the lack of infrastructure and the relatively low investment costs. For these reasons, truck-to-ship bunkering is a good provisional solution for LNG bunkering. In 2008, half the Norwegian coastal ferries running on LNG were regularly supplied by tanker truck, mostly overnight. At the moment, there is one bunker ship in operation and several are planned.
One of the main advantages of truck-to-ship bunkering is the limited investment costs for operators. The trucks can also be used for LNG distribution for other purposes.
The main drawback of LNG bunkering by means of TTS bunkering for large consumers is the limited capacity of trucks: approximately 40-80 m3. This bunkering method is only suitable for bunkering quantities up to 50 tonnes and is therefore only suited to smaller-sized LNG-fuelled vessels. Owing to the limited flow rate, bunkering takes about an hour (around 1,000 l/min). The presence of truck and bunker processes also impacts other quayside activities like cargo and passenger handling. Furthermore, a road connection with the preferred bunkering position is required, and local safety requirements need to be met, as with any bunker operation.
For capacity reasons, truck-to-ship bunkering is most suitable for smaller LNG-fuelled vessels with limited bunker volumes, like tugboats, inland vessels, coastguard vessels and smaller passenger vessels. The suitability of truck-to-ship transfer may also be influenced by restrictions on simultaneous cargo and passenger transfer. For reasons of safety, the large passenger vessel Viking Grace is refuelled by the bunker barge Seagas.
Ship to Ship
Ship-to-ship bunkering can take place at different locations: along the quayside, at anchor or at sea. It is the most common bunkering method used for bunkering seagoing vessels with HFO and MGO. The capacity of bunkering vessels can range from 1,000 to 10,000 m3. Because of size limitations in some ports, only smaller bunkering vessels will be able to operate in the port area.
Compared with other bunkering methods, the flexibility of ship-to-ship bunkering is high with respect to capacity and bunkering location. Because the bunker vessels are moored alongside LNG-fuelled ships, this bunker method could permit simultaneous cargo handling if approved by the relevant authorities, such as the port authority.
The high investment costs for bunker vessels is considered the main barrier. The industry is hesitant to invest in such vessels, in part because they have only limited alternative operations when LNG bunker demand is limited. However, several are being built or planned for the Zeebrugge/Antwerp/Rotterdam/Amsterdam region. Because LNG bunker vessels are regarded as vessels carrying dangerous cargo, entering non-Petroleum Harbour areas has to be authorized.
Given the high flexibility of bunkering vessels, ship-to-ship bunkering is suitable for all types of vessels and is expected to become the main bunkering method for ships with a bunker demand of over 100 m3. This implies that ship-to-ship bunkering is most suitable for large vessels such as RoPax/RoRo vessels, bulk carriers and container vessels.
Shore to Ship
Another bunkering method is shore-ship, whereby LNG is either bunkered directly from an (intermediary) tank or small station, or from an import or export terminal. Pipelines from the terminal to the quay are needed if the LNG terminal is not directly situated at the berth. Bunkering from pipelines has been used for LNG-fuelled ships in Norway for several years already. Under the LNG Masterplan, LNG bunker terminals for inland shipping are to be built in the Port of Antwerp and in Ruse, as pilots, while a feasibility study for an LNG terminal in the Port of Constanta is scheduled.
Shore-ship bunkering is generally a good option for ports with stable, long-term bunkering demand, especially in the case of co-use of LNG by other consumers. Because the pipeline and the loading arm arrangement are fixed, a larger hose can be installed to increase the bunkering rate (up to 3,000 l/min), leading to significantly shorter bunkering times.
One of the major drawbacks of this type of bunkering is the effort it takes a ship to get to the location of the bunker terminal (or pipeline). In addition, limited berth access for larger LNG-fuelled vessels can also be a barrier for shore-ship bunkering.Given the scale of import terminals, as well as for efficiency reasons, most ports will not be equipped with an LNG import terminal. However, ports lacking such a terminal can install fixed storage terminals or use bunker ships for LNG supply.
Shore-ship bunkering is especially suitable shipping services with a high frequency, limited demand, less strict timetables and limited vessel draft. Examples include bunkering vessels, tugs, inland shipping vessels, utility vessels and fishing boats.Shore-ship bunkering may also be a good option for inland shipping, because inland vessels have the flexibility to visit fixed stations, whereas seagoing vessels do not.