Energy Bridge Regasification Vessels, or EBRVs, are purpose-built LNG tankers that incorporate onboard equipment for the vaporization of LNG and delivery of high pressure natural gas. These vessels load in the same manner as standard LNG tankers at traditional liquefaction terminals, and also retain the flexibility to discharge in three distinct ways. These are:

  as liquid at a conventional LNG receiving terminal,

  as a gas through the EBRV’s connection with a subsea buoy in the hull of
  the ship, and

  as a gas through a high pressure gas manifold located forward of the
  vessel’s LNG loading arms.

Specialized Equipment

To accomplish the task of offshore LNG vaporization, EBRVs are designed to incorporate certain equipment and processes onboard, consisting of the five major components as listed below.

  High pressure cryogenic pumps – bring the LNG from the cargo tanks up to
  pressure prior to vaporization.

  Shell-and-tube vaporizers – convert the LNG back to vaporous natural gas.

  Oversized boiler - provides the steam and power necessary to sustain
  vessel operations and the shipboard regasification process.

  STL buoy compartment - designed to accommodate a submerged turret
  loading (STL) buoy system, which serves as the mooring system for
  the vessel.

  Reinforced LNG tanks and pump tower – designed to withstand the
  sloshing loads encountered throughout all loading levels while at sea

Vaporization of LNG

Each EBRV is capable of three modes of LNG vaporization designated as Closed-Loop, Open-Loop, and Combined Mode.

  In Closed-Loop mode, steam from the EBRV’s boilers is used to heat fresh
  water circulated through the shell-and-tube vaporizers in the regasification
  plant. This results in minimal usage of seawater by the EBRV.

  In Open-Loop¹ mode, sea water is drawn in through the EBRV’s sea chests.
  This seawater is used as a heat source and passed through the tubes of
  the shell-and-tube vaporizers, where the temperature of the seawater is
  lowered by approximately 13 degrees Fahrenheit (7 degrees Celsius). For
  this reason, the Open-Loop mode is not applicable for water temperatures
  below 45 degrees Fahrenheit.

  In the Combined Mode of operation, seawater at temperatures between 45
  and 58 degrees Fahrenheit can be used and is further heated using steam
  from the EBRVs boilers to provide sufficient heat for the vaporization of
  the LNG.

The maximum rate of discharge of the natural gas from an EBRV into the deepwater port will be determined by a combination of the availability of capacity on downstream pipelines and the regasification capabilities of the facilities located on-board each EBRV.

¹ The shipboard seawater LNG regasification technology used in Excelerate's ships operates under a patent grant from ExxonMobil Upstream Research Company.