25 September 2017

Regasification Vessel

The Floating Storage and Regasification Unit (FSRU) proposed for permanent mooring at the Port Meridian deepwater port, will have onboard equipment capable of converting liquefied natural gas (LNG) into a gaseous state suitable for transportation to shore via a conventional subsea pipeline.

The purpose of permanently mooring a FSRU at the Port Meridian deepwater port is to allow vessels without LNG regasification capabilities to discharge their cargo and have it regasified and transported into the National Grid. This will allow LNG to arrive from numerous global supply sources.

The FSRU will be permanently moored by means of a submerged unloading buoy and anchor array system. The STL Buoy system is already in use for offloading crude oil worldwide, including the North Sea (e.g., Banff, Fulmar and Harding fields on the UKCS).

Specifications

Specific details of the size and capacity of the regasification vessel;

  • Storage capacity 170,000 cubic metres (final storage capacity to be determined by level of market interest)
  • Tank type Moss 4
  • Length 310 metres (298 metres between perpendiculars)
  • Breadth 46 metres
  • Depth 26 metres
  • Draught 12.6 metres
  • POB 38 + 6 support crew

Support vessels, including two tugs for safe operations and one supply vessel for carrying stores, equipment, and supplies will be required during various activities and sourced locally.

The FSRU will have sufficient thruster capacity to enable it to rotate around the buoy in a ‘side by side’ configuration and also retain full propulsion capability. The vessel will therefore have the capability to be operated as a ship at all times.

The FSRU is capable of being readily disconnected from the STL and could therefore be un-moored from its location with full propulsion should a foreseeable event require, or in the event of an unanticipated event occuring.

Unloading Operations

Once operational, arriving LNG cargos will be transferred to the FSRU via Ship-to-Ship Transfer (STS), re-gasified onboard the vessel, and delivered through the STL buoy and sub-sea pipeline system for entry into the NTS grid.

During operations, an arriving LNG carrier (LNGC) will be moored in place using its own mooring equipment, with each mooring line being secured to a ‘quick release’ hook on the FSRU.

When moored for STS, there will be a separation distance of 4.5 metres between the vessels – sufficient to fit a fender between the two vessels to avoid damage.

It is expected that each visiting LNGC will be moored on location for up to 24 hours depending on cargo size, buffer status and throughput rate. The vaporisation systems together with pipeline dimensions are rated for a maximum throughput rate of up to 750 mmscfd.

Ship-to-Ship Transfer

The LNG will be transferred from the arriving LNGC to the FSRU through hoses or loading arms. The LNGC and the FSRU will be joined using special cryogenic couplings.  Procedures for STS are a proven technology and operations occur worldwide. Höegh LNG performs STS among their existing LNG fleet and are some of the original designers of this technology.

If fully utilised it is expected that, on average, an LNG cargo will arrive once a week, with each STS transfer lasting approximately 24 hours, and cargo regasification lasting up to one week. This would result in an expected maximum of 52 STSs per annum. In reality the number of arriving cargoes will vary, depending on the market demand.  While winter deliveries are likely to satisfy consumers’ need for heating, summer deliveries can provide a flexible supply that can be used to match the needs of electric generators.