Sunrise LNG in Timor-Leste: Dreams, Realities and Challenges
A Report by La’o Hamutuk
Chapter 3. The Plant
This section describes the processes that take place at the LNG plant and the major technical requirements to site the facility. At the end of Chapter 6, which discusses environmental and safety concerns, we describe the current status of disaster preparedness in Timor Leste.
The LNG plant envisioned for Timor Leste is a liquefaction plant, a facility that will receive the natural gas from the Greater Sunrise undersea reservoir through a long undersea pipeline, and lower its temperature to liquefy it for storage and later shipping to overseas customers. The plant is constructed as one or more processing “trains” which receive the gas, filter and cool it, and store the liquid in a tank until a tanker ship picks it up. Many plants are first constructed as a single train, with additional trains being added later to increase the processing capacity as additional gas reserves come on line.
The process at the liquefaction plant can be divided into three main areas: feed gas preparation, fractionation, and liquefaction. This description of these processes follows Alexander S. Adorjan’s explanations .
The liquefaction cycle for natural gas requires cooling it to about -160°C. Therefore, the incoming gas needs to be cleaned of substances that could freeze at these temperatures and cause plugging in the equipment. These components are typically water vapor (H2O), carbon dioxide (CO2), and higher-level hydrocarbons, which may be commercially useful in themselves. Hydrogen sulfide (H2S) is removed for safety reasons while traces of mercury are also removed to avoid corrosion in the equipment. (Woodside estimates that the Sunrise reservoir fluids contain an average of 5 mol% CO2 and 10 mg/m3 total sulfur. ) The operations needed involve refrigeration, absorption, and adsorption processes, and must be engineered to match the particular composition of the natural gas from Greater Sunrise. The feed gas preparation operation is cheap in terms of the relative cost of the equipment (for instance, acid gas removal equipment may constitute only 5% of the plant capital cost), but this process requires a lot of energy. Removal of 5% CO2 from the feed gas can consume more than 25% of the energy of the total plant.
In the case of the Wickham Point facility that liquefies processes Bayu-Undan gas in Darwin , an aqueous, organic, amine bath is used to remove CO2, small quantities of H2S and other sulfur components. These components, usually referred to as acid gas, are later removed from the amine solution in a stripper. Water is removed in this facility partly in the first phase of gas chilling which condenses some of the water and, subsequently, in a three-bed molecular sieve that removes the rest of the water vapor. The traces of mercury are removed through two beds of activated carbon.
In addition, nitrogen gas, although not a contaminant, is removed from the gas when its content is higher than 0.5% because it depresses the heating value of the final natural gas product, it reduces the boiling point of the feed gas, and its presence increases the occurrence of rollover in storage tanks and vessels.
Higher-level hydrocarbons are removed in the Liquefied Petroleum Gas (LPG) fractionation process. This part of the plant may cost about 3% but requires about 10% of the total energy. Since LPG is a marketable by-product of the LNG plant, fractionation is an important factor in the overall plant economy. It could be done at sea or in the LNG plant itself, as described in Box 5.
In the liquefaction cycle, the heat is removed from the natural gas in four distinct stages: cooling and condensation, expansion and flashing, evaporation, and compression. The efficiency of the liquefaction process can be improved by using multi-stage refrigeration, either with the cascade cycle (see Figure 7) or the mixed-refrigerant cycle. In the first method, the liquefaction involves refrigerants such as butane, propane, ethane, methane, nitrogen, or their mixtures. The gas is thus cooled in successive steps. It is a rather costly cycle depending on the number of stages with a compressor, heat exchanger, storage tank and other components required for each stage of the cycle. Although both systems provide similar efficiencies, the mixed-refrigerant cycle requires a lower initial investment. In that process, the working fluid is expanded at different pressure levels and the liquid and gas are separated after each expansion. The gas is then compressed while the liquid passes onto the next refrigeration stage.
The power for all of these operations can be provided by steam turbines, gas turbines, combined gas and steam turbines, or electric motors. Steam turbines are typically more flexible and have a characteristic thermal efficiency of 25%. Gas turbines have higher efficiencies of about 30-35%, although they are less flexible than steam turbines in regard to power control. Gas turbines are also more sensitive to changes in ambient temperatures.
Once the liquefaction process is completed, the LNG is stored in double-walled containment tanks. These tanks are especially designed and cooled to contain the liquefied gas until it is loaded into tankers. Tank designs typically use a double container system which consists of an inner 9%-nickel steel tank and an outer steel or concrete tank  (see Figure 8). The space between the two tanks is filled with a thermal insulator (perlite). The bottom of the tank is heated to avoid freezing the soil below. If the tanks are partially buried below grade, the walls are also heated.
A dock is also necessary to transport the LNG from the storage tanks to the LNG tankers. The characteristics of this facility will be briefly described in the following “Siting the plant“ section due to the importance of navigational access in siting the facility.
The plant will have its own electric generating facility, as it needs power in larger and more reliable amounts than the EDTL grid can supply. This generator could increase environmental pollution, depending on the fuel used. It could also be designed to produce more power than the plant requires, thereby servicing nearby communities.
South of the island of Timor, between the shoreline and the location of the gas reserves of Greater Sunrise, the bottom of the sea displays a great depression (an underwater valley) more than 3,000 meters deep in places. This formation is known as the Timor Trough and it was formed as a consequence of the collision of the tectonic plates containing Australia and Asia. The southbound drifting Eurasian plate is colliding with the Indian-Australian plate in the Banda Sea north of Timor island. This collision has folded the Australian plate, thereby forming the Timor Trough and Timor island itself, which is part of the Banda Orogen. (The crash between these plates results in an “orogen” which is a mountainous formation generated from tectonic processes. Timor Leste is technically a part of the “Banda Orogen,” the formation created when the Australian Plate buckled as a consequence of the tectonic clash.) This process has also fractured the Australian plate along a number of small fault lines in the Timor Sea. The formation of the island of Timor was studied by Audley-Charles  and others, although many of the aspects of this geological history still pose unresolved enigmas.
Several challenges need to be resolved to find a suitable site for the LNG plant in Timor-Leste:
A location has not been decided, and several technical studies should be conducted prior to this decision .
As explained before, an LNG plant is a complex structure with many interdependent parts. A typical construction phase of a LNG plant will involve major engineering projects in two phases, and several sub-phases, needing three to six years:
Building an LNG plant on the south coast of Timor-Leste will require constructing various supporting infrastructure. Works related to the construction of the plant itself and this infrastructure will start at different times and last different periods, with some overlapping with others. It is possible, however, to indicate several main categories with an indicative list of works, outlined below and summarized in Table 2. Specialized companies are usually sub-contracted do perform various works and services, such as dredging and other marine works. Also, some items will be built mostly on-site while others, such as gas-turbine electricity generators and major components of the LNG process, will be shipped in ready-made and be assembled at the site.
The plant site will approximately occupy 1-2 km2 of land when built closely together and will be close to the shore, but sufficiently elevated to avoid flooding of the site. Clearing the site of vegetation and commencing initial leveling can be done with typical earthmoving machinery, which can be transported to the site either by road on flatbed trucks or landed by barge. Earthworks could total over 2 million cubic meters in volume. For comparison, preliminary calculations for the expanded Darwin LNG plant, which will be capable of processing 10 mtpa, estimated 1,600,000 m3 of “cut” and 1,000,000 of “fill” earthworks (cutting down hilly areas and filling up lower areas; this is more or less a simultaneous process). 
During meetings between La’o Hamutuk and staff and advisors of the Ministry of Natural Resources in 2006 , government technical consultants expressed their preference to transport all machinery and supplies by sea with barges, thus avoiding the reconstruction of the road infrastructure in Timor Leste. However, if the road system were improved, access roads could link the plant site to the Timor-Leste road network providing opportunities for local sourcing of personnel, construction equipment and materials, as well as using Dili airport and seaport facilities. Still, a good north-south road connection will not fulfill all needs, and it will be necessary to build a construction dock as early as possible to allow for heavier machinery as well as shipping of pre-manufactured processing modules and probably personnel. It may be possible to engineer this construction dock and shipping lanes to serve as a commercial port, which would extend its functionality beyond servicing the LNG plant, but proper needs and risk assessments must be carried out (see Chapter 6).
A typical construction dock consists of a T-shape structure extending from the coast into water, usually constructed with rockfill and armor stone in combination with steel plate and steel pile reinforcement and a concrete deck. Specific design requirements depend heavily on type of shoreline and coastal depths. For comparison, the Darwin LNG plant possesses a construction dock with a 20 m wide groin (the vertical bit of the T) extending 570 m from the plant site into the sea and ending up in a rectangular dock (the horizontal bit of the T) measuring 30 m by 50 m. (See Figure 12.) Additionally, a berthing pocket measuring 40 m by 200 m and an approach channel measuring 70 m by 1000 m were dredged. Approximately 675,000 m3 of landfill and 135,000 m3 of armor stone were used, with the landfill coming from site leveling works, and 145,000 m3 of dredge spoil was created. A construction dock will need its own environmental impact assessment, to be packaged independently or jointly with the LNG project.
Out of safety concerns, LNG tanker loading facilities are kept separate from other docks, necessitating construction of a second jetty structure, or perhaps a y-split structure. However, LNG loading facilities usually extend further into the sea to because LNG cargo ships require greater depth (a typical tanker will have a capacity greater than 100,000 m3), and berthing pockets and the approach channel are larger and deeper. Tankers also need a vessel turning basin perhaps 600 m in diameter. The loading facility needs some specialized pipeline-to-ship connection machinery. The marine works for both the construction and tanker docks could be done by the same company.
LNG plants incorporate their own power generating stations because they need large quantities of electricity, which could be done through using some of the gas to fuel electricity generators. However, the construction phase will already require electricity which will have to be provided initially by a diesel generator and accompanying fuel storage tanks on-site or through direct linking to the local electricity grid. (The Darwin LNG plant was supplied with four megawatts (peak rate) of power during the construction phase, although most of its energy needs during operation are supplied by gas turbines. ) The latter option requires sufficient preparation to provide enough electricity and to guarantee a continuous supply. LNG plants require water for operating (cooling process, cleansing gas of polluting agents, fire prevention, etc.), and therefore require a sufficient, guaranteed water supply. Water will also be required for initial construction, mainly cement works, and for consumption throughout all phases, requiring early establishment of water supply and treatment. (The Darwin LNG plant was supplied with 80 m3/hour (peak rate) of water. ) Construction and operation of this scale will also require well-functioning communications, including independent emergency fall-back systems. Likewise, an early installment of facilities for concrete batching can significantly increase speed of works and avoid unnecessary delays.
One important factor of construction work is the relative remoteness from populated areas, necessitating fairly early building of sufficient accommodation for the construction workforce (which could be over 1000 workers at later peak periods). During construction of the Darwin LNG plant, similar numbers of workers were accommodated in Darwin. Only 25% of the workers came from the Darwin area and probably had their own accommodation. Building housing for the others could require extra site clearance, or another designated area, to accommodate close to a thousand people. (Employment is discussed at length in Chapter 5.)
Secondary plant facilities will support the technical and mechanical operation of the plant. Many temporary facilities from the initial construction camp will be transformed into or replaced by permanent facilities. Although many facilities will be more or less standard (there really are not many ways one can build a warehouse), some buildings, such as a laboratory, have a more specialized function requiring more international content.
The main electricity generator for the plant deserves special mention. A pipeline and liquefaction complex consumes a large amount of energy. Given the undeveloped system of electricity generation in Timor-Leste, the LNG plant will have to be self-sufficient in energy, using some of the feed gas to fuel a power station located within the plant. The energy needs of the liquefaction process will require a capacity on the order of several hundred MW. For comparison, the power plant at Snøhvit LNG has a generating capacity of 225 MW, and the facility consumes an additional 45 MW from the main electricity grid . It is likely that an LNG plant in Timor-Leste will have even larger energy needs than this, given the possibly larger rate of production, the higher ambient temperature, and the longer pipeline. (The RDTL government has planned to provide electricity to 80% of all households in Timor-Leste by 2025, which will require 110 megawatts of generating capacity. This is triple Timor-Leste’s current capacity but less than half what the LNG plant would require. ) Gas turbines could provide much of the power needed to run the plant either directly or through electricity.
While such generating capacities are far beyond anything currently available in Timor-Leste, they are standard in the world of heavy engineering. Thus one could straightforwardly install a turbine with a capacity around 400 MW, which comes as standardized products from manufacturers. Purchasing and installing such a generator might cost around US$400 million, according to one engineer familiar with LNG projects.  It would be possible to build a gas-fuelled power station with sufficient generating capacity not just to power the pipeline and liquefaction plant, but produce additional electricity for domestic use (although, of course, this requires appropriate transmission lines and infrastructure as well as a thorough consideration of all safety concerns). The power plant could be built at the same time as the pipeline and be ready to produce energy as soon as the pipeline was connected and the upstream facilities were producing gas, which could be before the LNG plant was ready or even under construction.
Another aspect of construction work is the generation of waste. This initially includes vegetation during site clearing, but soon diversifies into building materials, domestic garbage, sanitary wastewater, drums and containers, spent oils, paint and hazardous materials, which require proper waste collection and disposal systems. The composition of construction waste differs from waste generated during operation of the plant, but general methods of waste management are similar. Although many other LNG plants are built where there is sufficient existing waste management capacity to sub-contract waste disposal to third party companies. However, mechanisms such as general landfill, high temperature burning, recycling, or sequestration and permanent isolation from the environment will need to be established from scratch in the south of Timor-Leste.
After all gas fields have been used up resources are exhausted and no feed gas is available for the LNG plant, it will be shut down and decommissioned. In the case of a “special purpose company” as discussed during the April 2007 roundtable discussion , the trustees could be mandated to sell the plant to Timor-Leste “as is” for a fixed price. This could be useful if additional natural gas fields are found in Timor-Leste.
In the case the plant should be removed, normal practice dictates that plant equipment and piping should be purged of hydrocarbons and all other chemicals and materials with possible toxic effects. Plant and office equipment could be sold where possible unless the facility is sold as is. Equipment that cannot be sold should be disassembled and sold as scrap or disposed of in accordance with regulatory guidelines (which should be in place at the start of the project to have any jurisprudential weight). Regulations in Timorese law will define exactly how decommissioning should take place, and, although it seems far away, the government needs to consider now the implications of decommissioning a plant of this magnitude.
The Timor-Leste Petroleum Act  passed in 2005 requires companies decommissioning exploration and extraction facilities “to clean up the Authorised Area and make it good and safe, and to protect the environment,” and stronger legislation needs to be passed for downstream and other large industrial projects on Timor-Leste’s land. An LNG plant here will be a greenfield project (a project built on previously undeveloped land), so Timor-Leste law should require that the site be returned to its natural state, and that all waste and materials be removed or permanently and safely isolated from the environment. Generally, decommissioning means that after a long and stable period of minimum employment, there will be a minor spike in employment related to deconstruction and landscaping.
The Timor-Leste Institute for Development Monitoring and Analysis (La’o Hamutuk)