3                                            What is Required to Bring LNG to Hong Kong

3.1                                      The LNG Supply Chain ([1])

The process of LNG production involves the transport of the natural gas from the production fields via pipeline to a liquefaction plant.  Prior to liquefaction the gas is first treated to remove contaminants, such as carbon dioxide, water and sulphur to avoid them freezing and damaging equipment when the gas is cooled to -162°C.  The liquefaction plant is similar to a large refrigerator with compressors, condensers, pressure expansion valves and evaporators. 

The LNG produced from the refrigeration process is piped to specially designed LNG storage tanks.  Both the piping and tanks are insulated to maintain the low temperature and constructed using special materials to contain the cryogenic liquid.  LNG is then drawn from the storage tanks and loaded onto specially equipped LNG carriers.  The carrier delivers LNG to a receiving/regasification terminal where it is stored in LNG tanks and converted back to a gaseous state prior to being dispatched/piped to the end-user such as a power plant when needed.

The whole process is referred to as the LNG Supply Chain and is illustrated in Figure 3.1.  The only elements of the supply chain that will take place in Hong Kong are the development and operation of the receiving terminal and the marine transit of LNG in a LNG carrier to the terminal site.

Figure 3.1       LNG Supply Chain

3.2                                      LNG Receiving Terminal

Near the end of the supply chain is the receiving terminal. The key components of the proposed LNG terminal, including marine jetty facilities for unloading LNG, special tanks for LNG storage, process equipment for the regasification of LNG, utilities and other infrastructure, are depicted in the process overview (Figure 3.2).  Site specific details of the LNG terminals at the two selected sites are presented in Part 2- Section 3 and Part 3-Section 3.

Figure 3.2       LNG Terminal Key Components and Process Overview

A receiving terminal, similar in size to this project, will typically require approximately 30 - 40 ha of land to locate the necessary infrastructure, which includes the following:

·       Jetty and unloading arms

·       Process Area

·       LNG Tanks

·       Low Pressure and High Pressure pumping systems

·       Vaporisation (Regasification) Area

·       Vents (low pressure and high pressure)

·       Maintenance Workshop

·       Administration Building

·       Guard House

·       Utility Area

·       Control Room

3.2.1                                Marine Facilities

A jetty and unloading arms are required to transfer the LNG from the carrier to the terminal.  The length of the jetty is defined by specific site conditions, and the maximum length overall of the LNG carrier that will deliver the required cargo volume.  In addition, a turning circle of sufficient size and depth is required to allow for turning the LNG carrier either prior to berthing or on departure after completion of unloading. 

The unloading arms are moved with a remote-controlled hydraulic system located on the berth.  When they are lined up with the LNG carrier, the two are then secured by bolts or quick connect couplings.  Five arms are typically installed, three for unloading LNG, one for return vapours and one spare that can be used for either service.  After connection is completed, the communication cable is connected to shore and the emergency shutdown system is tested. 

After the unloading arms are cooled, the LNG will be transferred from the carrier to the storage tanks using the carrier's pumps.  The discharge of LNG from the carrier takes approximately 18 hours.  In addition, approximately 3 hours are required for mooring, cool down, connecting unloading arms, and cargo measurement, and approximately 3 hours for cargo measurement, arm purging, disconnecting arms, and unmooring.

3.2.2                                LNG Storage Tanks

Following berthing, the LNG is pumped ashore via the carrier’s pumps through unloading arms to a cryogenic pipeline and on to the storage tanks.  For this project, an above-ground, full containment design has been selected.  The LNG will be stored near atmospheric pressure and in full-containment LNG tanks that typically consist of the following:

·      Primary inside tank - made of a "cryogenic material" such as 9% Nickel steel, aluminium alloy or reinforced pre-stressed concrete; it is now common practice to use 9% Nickel steel for the inner tank in LNG service;

·      Insulation – loose insulation material (such as perlite) surrounding the inner nickel steel tank (sides, floor and roof);

·      Vapour barrier tank – made of carbon steel to contain the insulation system and vapour pressure of the primary tank;

·      Outer tank – reinforced, pre-stressed concrete designed to independently store both the LNG liquid and vapour should the inner wall fail; and,

·      Domed roof – reinforced, pre-stressed concrete.

An illustration of typical full containment tank is presented in Figure 3.3.

Figure 3.3      Example of a Full Containment LNG Storage Tank

LNG tanks are specially designed to contain the LNG at its cryogenic temperature of approximately -162 °C near atmospheric pressure.  After initial transportation planning, which includes detailed shipping and storage simulation modelling of Black Point Power Station’s requirements with regard to LNG volume, minimum inventory, and potential sources of supply and ship sizes, a LNG storage facility comprising two tanks of 160,000 to 180,000 m3 each is planned.  Space will be provided for a third tank for future expansion (180,000 m3 tanks may be considered).  This EIA is based on three LNG storage tanks, i.e., a total capacity of 540,000m3. 

The LNG tanks have a top entry point for both the loading and unloading operations.  Two submerged send-out pumps per tank will be suspended from the top of the tank and pump the LNG out of the tanks.  All tanks will be designed to simultaneously send out (to the vaporiser units) and to receive LNG (from unloading LNG carriers).  The tanks will be fitted with a low-pressure vent, which will provide storage tank overpressure protection if the tank pressure exceeds the maximum operating limit of the LNG storage tank design pressure. 

3.2.3                                Other Major Process Facilities

Vapour Handling System and Boil-off Gas (BOG) Condenser

Boil-off gases (BOGs) are produced during normal terminal operations as a result of inevitable heat transfer arising from the storage and handling of LNG.  This BOG is captured and sent to the BOG compressor for re-condensing (liquefying).  A second BOG compressor will serve as a backup or a spare.  The BOG condenser outlet liquid stream flows to the HP LNG Booster pumps to raise the LNG to the send-out pressure before feeding the LNG to the LNG vaporisers.  LNG is heated and converted back to gas in the vaporiser unit. 

LNG Vaporisers

Stored LNG will need to be re-gasified in order for it to be transported by gas pipeline to the point of use.  This will be accomplished via LNG Vaporisers, which will either utilise piped seawater (in open rack vaporisers) or hot combustion gases (in submerged combustion vaporisers) to raise the temperature of the LNG to ambient, thereby causing it to re-gasify.  Once the LNG is vaporised the gas is then regulated for pressure and piped to the consumer. 

Open Rack Vaporisers – The seawater will pass through a series of screens to remove debris to prevent blockage or damage to the seawater pumps before entering the open-rack vaporises (ORVs).  In ORVs, seawater flows over the exterior of the vaporiser panels, which internally channel an upward flow of high-pressure LNG (HP LNG).  LNG will then be vaporised by exchanging heat with seawater in the ORV’s.  The seawater flows over the panels to a trough below and is then discharged back to the sea via a submarine outfall. 

Submerged Combustion Vaporisers - In Submerged Combustion Vaporisers (SCVs), LNG flows through tubes that are submerged in a heated water bath.  LNG will then be vaporised.


Each LNG storage tank will be configured with two in-tank LNG send-out single-stage centrifugal pumps.  LNG send-out pumps discharge to the HP LNG booster pumps.  The HP LNG booster pumps will be designed to meet the required send-out pressure for the pipeline option.  Six HP LNG booster pumps including one spare will be used in the expansion case.

Gas Meter Stations

The outlet gas from the vaporisers will be metered at metering stations and sent to the gas pipeline at South Soko (South Soko option only).

Fuel Gas System

The fuel gas system including high- and low-pressure fuel gas systems will provide sufficient fuel gas for the various terminal users such as power generation, heating, and any SCV’s in operation.  Vaporised high pressure natural gas will be used for on-site power generation, while the low-pressure fuel gas system will provide sufficient natural gas for the various terminal users such as SCV, heating the gas to the gas turbines for power generation when needed, and other heating requirements.  BOG and/or letdown vaporised LNG will be used for low-pressure natural gas at approximately 5.5 barg (80 psig).

Vent and Relief System

The LNG terminal is designed for the safe handling of vapour discharges from the system, such as from relief valves, which are sent to the vent header and then to the separator before going to the vent stack.  There are two vent systems, a high-pressure (HP) vent stack and a low-pressure (LP) vent stack.

The LP and HP vent system is designed for the following possible situations:

·      All the equipment will be provided with pressure relief devices.  In the case of over-pressuring, the relieved vapour will be vented to the vent stacks which are designed to safely route the gas away from hazardous areas.

·      LNG tank roll-over ([2]) and BOG from a sudden drop in barometric pressure.

·      In the event of total facility power failure, the LNG send-out and the unloading operations will be stopped and the boil-off gas will be routed to the LP and HP vent systems.

3.2.4                                Utilities and Ancillary Facilities


Nitrogen is required at the terminal for equipment purging and maintenance purposes.  Adequate on site nitrogen generation and storage for liquid nitrogen will be provided at the terminal.  The nitrogen generation and storage tank size are based on normal purging and maintenance requirements.  For start-up and/or LNG tank purging, additional nitrogen will be made available on site by providing liquid nitrogen tanks from supply vehicles.


Instrument and utility air for use within the terminal are produced on site.  Two air compressors on lead-lag demand, one dual and regenerative instrument air drying system, separate instrument and utility receivers, and piping headers will be provided. 

Power Generation

The power supply for the LNG terminal can either be generated on-site using a gas turbine or imported.  A battery supplied UPS (Uninterrupted Power Supply) system powers the Emergency Shutdown (ESD) and gas and fire systems to ensure the operation of critical systems in the unlikely event of a complete failure of the power.

Waste and Wastewater Treatment

A system will be provided for the treatment of wastewater.  A sanitary waste system consisting of a collection system, and a purpose designed and fabricated packaged sewage treatment unit will be provided.  Domestic wastewater from the administration building and the various terminal control rooms will be treated at the sewage treatment unit prior to discharge.  Sewage treatment will be via chemical or biological treatment methods in accordance with Hong Kong Government regulations.

Solid wastes will be collected and sent to the appropriately licensed disposal facility.


The terminal will be outfitted with up-to-date communications equipment capable of maintaining contact with the LNG carriers scheduled to offload at the terminal and with the standby tugs.

3.2.5                                Buildings

The following permanent buildings will be provided on site for the operational phase:

·      Administration Building – the administration building will provide offices, communications and a galley.  For the South Soko option, it will also provide accommodation for approximately 50 persons.

·      Control Building - the control room will contain all facility control functions, including plant monitoring, safety and control equipment consoles. 

·      Maintenance/Warehouse Building - equipment and spare parts will be stored in this building.

·      Switchgear/MCC Building - will house switchgear, motor control centres, panel boards, UPS, batteries and battery charges, lighting transformers, PLC panels for switchgears, MCCs, generator control panels and other equipment.  Power distribution transformers will be located on the roof of this building.

3.2.6                                Protective Systems

Gas Detection, Alarm, Firefighting and ESD Systems

A centralised spill, fire and combustible gas alarm and control system will provide input to an information management system.  Automatic detection devices, manual alarms and audible and visual signalling devices will be strategically located throughout the terminal.  Automatic detection devices will include flame, fire and heat, smoke, low temperature and combustible gas detectors.  CCTV monitors will be installed to allow visual surveillance of critical facilities from the central control room.  An emergency shutdown system (ESD) will be incorporated in the design of the terminal and provide the operators with the capability of remotely shutting down the entire or selective portions of the terminal.  The unloading arms will also be equipped with Powered Emergency Release Couplers (PERCs).  The PERC maintains containment integrity and prevents damage to the unloading arms in the event of an emergency.


Security will be designed to prevent unauthorised access and to ensure the safety and integrity of the facilities.  The site will be provided with a perimeter fence and access will be restricted.  Perimeter lighting will also be provided.

3.3                                      LNG Carriers ([3])

LNG carriers have insulated cargo tanks and are of double-hull design.  The double hull provides the location for the segregated ballast and provides optimum protection for the integrity of the cargo tank containment in the unlikely event of collision or grounding.  There are two types of LNG carriers:  Moss and Membrane ([4]) (Figure 3.4). 

Currently, a typical LNG carrier has a Length Overall (LOA) of approximately 285 m, a 43 m beam and a 12 m draft, with a cargo capacity of around 145,000 m3.  The LNG is transported in the tanks near atmospheric pressure and the boil-off gas can be used to supplement liquid fuels for propulsion.  LNG carriers of larger capacities are under development ([5]).  LNG carriers of larger capacities, up to 215,000 m3 are currently being built for other projects and a carrier of this class has been selected for this EIA Study.

As illustrated in Figure 3.4 for Moss carriers four or five spherical tanks contained in the hull, with a substantial proportion of each tank above the weather deck.  In a membrane design the larger proportion of each tank is below the weather deck (Figure 1.3 ).  Both carrier types are commonly utilised for LNG transit with no significant operational difference between them.  Consequently, a navigable water depth of approximately -15m PD will be required for the vessels’ transit to either Black Point or South Soko.  That is similar to the requirement for bulk carriers and container ships currently trading to Hong Kong.

Figure 3.4      Moss and Membrane LNG Carriers

Prior to entry into Hong Kong waters, the LNG carrier will perform thorough pre-arrival safety checks on all critical equipment.  Then when navigating in Hong Kong waters all LNG carriers will be required to have two experienced local pilots on board.  The pilots provide local knowledge of the navigable route for the LNG carrier to the jetty.  When the local pilot boards the LNG carrier, crew and the pilot will exchange navigational information to ensure the entire bridge navigating team work together to achieve safe passage through Hong Kong waters to the LNG berth.  In addition, the appropriate number and size of tugboats are available for response should an emergency arise.  These can also assist in facilitating diversion of traffic on a heading that would require the carrier to deviate from the intended track.  The LNG carrier typically will be turned 180 degrees before berthing and then be slowly manoeuvred towards the berth, assisted by the tugs.

3.4                                      Global LNG Industry

The world’s first large scale LNG trade began in 1964, with the UK as the importing country.  Since then, the LNG industry has built up globally and in 2005 there were 13 countries producing (liquefaction) LNG and 15 importing/receiving (re-gasification) LNG.  The world’s four largest producers in 2005 were Indonesia (17% global production), Malaysia (15%), Qatar (14%) and Algeria (13%) ([6]).

In terms of consumption of LNG, the largest importer by far is Japan, which has 25 receiving terminals (Figure 3.5).  In 2005 these terminals received over 40% of the world’s LNG imports ([7]), equivalent to roughly 36 times the annual gas consumption of the Black Point Power Station.  East Asia as a whole accounts for over 60% of world’s LNG imports through the terminals in Japan, South Korea, Taiwan and India.  Mainland China began to be an importer recently with the commissioning of the Guangdong Dapeng LNG terminal.  A terminal in Fujian is under construction while others are in their planning or proposal stages (Figure 3.6).

In Europe there are 14 LNG terminals.  France is the largest importer of LNG (Figure 3.7).  Other countries with terminals include Spain, Italy, Greece, Turkey, Portugal and Belgium and further receiving terminals are planned or under construction in the UK, Spain and Turkey.

In the Americas there are 5 receiving terminals in the US, 1 in the Dominican Republic and 1 in Puerto Rico (Figure 3.8).  The Americas is currently the area with the largest number of planned/proposed receiving terminals.  Africa has no import terminals at present but has export terminals in Algeria, Libya, Egypt and Nigeria (Figure 3.9).

3.5                                      LNG Safety

The LNG industry has an excellent safety record ([8]) in all aspects of shipping, storage and regasification.  This is due to both the high technical standards that are used in the design, construction and operation of LNG facilities and carriers and also the physical properties of LNG, as described in Section 2.2.  In part, the safety record is a result of the adoption worldwide of a series of standards, codes and regulations ([9]).

3.5.1                                Shipping

LNG shipping has an outstanding safety record ([10]).  LNG has been safely transported across the world’s oceans over the last 40 years.  In that time there have been over 45,000 LNG carrier voyages covering more than 90 million miles without any loss of life in port or while at sea ([11]).  At the end of 2005, there were approximately 190 LNG carriers in the world fleet.

LNG carriers frequently pass through areas and ports that have high traffic densities, such as in Japan.  The favourable safety record of LNG carriers is largely due to their double-hull design and multiple levels of protection associated with cargo operations, as well as the industry’s focus on safety in operations, maintenance and crew training.

3.5.2                                Safety Considerations in LNG Carrier Design and Operation 

LNG carriers have insulated cargo tanks and are of double-hull design.  The double hull provides the location for the segregated ballast and provides optimum protection for the integrity of the cargo tank containment in the event of collision or grounding.  LNG carriers also have safety equipment to facilitate ship and cargo system handling.  The ship-handling safety features include sophisticated radar and positioning systems that enable the crew to monitor the carrier’s position, traffic and identified hazards around the carrier.  A global maritime distress system automatically transmits signals if there is an onboard emergency requiring external assistance.  The cargo-system safety features include an extensive instrumentation package that safely shuts down the system if it starts to operate outside of predetermined parameters ([12]).  LNG carriers also have fire detection systems and gas leak detection within the cargo tank insulation, and nitrogen purging for hold space and interbarrier protection.  Should a cargo tank on a LNG carrier be subjected to fire exposure, two safety relief valves are fitted to each cargo tank to provide vapour release to atmosphere thereby preventing over-pressuring of the tank from boil-off. 

LNG carriers are provided with instrumentation to ensure that the prescribed approach velocity for the berth fenders is not exceeded.  When moored, automatic mooring line monitoring provides individual line loads to help maintain the integrity of the mooring arrangement.  When connected to the onshore system, the instrument systems and the shore-ship LNG transfer system acts as one system, allowing emergency shutdowns of the entire system from carrier and from shore.  LNG carriers and facilities have redundant safety systems, for example Emergency Shutdown (ESD) systems.  A redundant safety system shuts down unloading operations when the carrier or unloading facility is not performing within the design parameters.

3.5.3                                LNG Receiving Terminals

LNG receiving terminals also have an outstanding safety record.  Safety of receiving terminals is ensured by five elements ([13]) that provide multiple layers of protection both for the safety of the LNG industry workers (on-site population) and the safety of the community (off-site population).  While these safety elements apply to receiving terminals, some are also applicable to LNG shipping. 


·      Primary Containment:  This is the first and most important requirement for containing the LNG product.  This first layer of protection involves the use of appropriate materials as well as the proper engineering design of storage tanks onshore and on LNG carriers.

·      Secondary Containment:  This ensures that if leaks or spills occur beyond primary containment, the LNG can be fully contained and isolated. 

·      Safeguard Systems:  The goal of these systems is to limit the frequency and size of LNG releases and prevent harm from potential associated hazards, such as fire.  Typically this will involve the use of technologies such as high level alarms and multiple back-up safety systems, which include Emergency Shutdown (ESD) Systems.  All LNG facilities have set operating procedures, training, emergency response and regular maintenance to protect people, property and the environment.

·      Separation Distances:  Accepted codes, such as the European Standard ([14]), give guidelines for the design, construction and operation of stationary LNG installations, including those for liquefaction, storage, vaporisation, transfer and handling of LNG.

·      Codes and Standards:  LNG industry standards, codes, and regulations have been developed over years of application.  Importantly, they incorporate lessons learned from the very few failure incidents related to single containment tanks in the early period of the LNG industry (1940-1970).  These proven codes and standards ([15]) help ensure safety and reliability.  Organisations such as the Society of International Gas Tanker and Terminal Operators (SIGTTO), Gas Processors Association (GPA), European Standard (EN), and (NFPA) produce guidance which results from industry best practices.


([1])      ‘Introduction to LNG’, University of Houston, Institute of Energy, Law & Enterprise

([2])      Rollover. When LNG supplies of multiple densities are loaded into a tank one at a time, they do not mix at first.  Instead, they layer themselves in strata within the tank.  After a period of time, these strata may spontaneously rollover to stabilize the liquid in the tank.  As the lower LNG layer is heated by normal heat leak, it changes density until it finally becomes lighter than the upper layer.  At that point, a liquid rollover would occur with a sudden vaporization of LNG.  The vapours produced would be sent to the vent system.

([3])      ‘Introduction to LNG’, University of Houston, Institute of Energy, Law & Enterprise

([4])      There is a third type referred to as the structural prismatic design which is used by approx 5% of LNG carriers.

([5])      Different sizes of carriers are under development, such as 200,000 m3, 220,000 m3 and 250,000 m3

([6])      Wood Mackenzie Research

([7])      The Changing World LNG Market and its Impact on Japan, The Institute of Electrical Engineer Japan, June 21, 2005

([8])      LNG Safety & Security, University of Houston, Institute of Energy, Law & Enterprise

([9])      LNG Safety & Security, University of Houston, Institute of Energy, Law & Enterprise

([10])    Introduction to LNG’, University of Houston, Institute of Energy, Law & Enterprise

([11])    Introduction to LNG’, University of Houston, Institute of Energy, Law & Enterprise

([12])    University of Houston, Institute of Energy, Law & Enterprise, Report titled ‘Safety and Security’.

([13])    University of Houston, Institute of Energy, Law & Enterprise, Report titled ‘LNG Safety and Security’, Page 11.

([14])    The European Standard EN 1473 – Installation and Equipment for Liquefied Natural Gas – Design of Onshore Installations

([15])    Such as European Standard EN 1473:1997 - Installation and equipment for liquefied natural gas – Design of onshore installations