Fujairah F2, a combined-cycle power and desalination plant under construction in the United Arab Emirates (UAE), is the seventh and largest independent water and power plant (IWPP) project to be commissioned by the Abu Dhabi Water and Electricity Authority (ADWEA) since Abu Dhabi reorganized its power and water sectors back in 1998.
Fujairah F2 IWPP is currently under construction at Qidfa on the Indian Ocean coast of the emirate of Fujairah
The project is being built in the Emirate of Fujairah, the most easterly of the emirates in the UAE, adjacent to the site of an earlier power and water plant. A consortium comprising ADWEA, International Power and Marubeni Corporation have formed a new project company à‚— the Fujairah Asia Power Company (FAPCO) to develop, own and operate the plant. This company has awarded the engineering, procurement and construction (EPC) contract for Fujairah F2 to a consortium of Alstom and Sidem.
When completed (expected in 2010) the new IWPP will have a net generating capacity of 2000 MW of power and 130 MIGD (million imperial gallons/day, equivalent to approximately 600 000 m3/day) of potable water.
The deal to build the plant followed a competitive tendering process under which bids were solicited by ADWEA in April 2007. The winning consortium signed a power and water purchase agreement in July 2007. Shortly after this, the EPC contract was signed between the developers and the Alstom-Sidem consortium.
The new plant will supply both to the Northern Emirates and to Abu Dhabi itself. ADWEA has recently signed a memorandum to supply power to the Northern Emirates. The project is also part of an expansion in capacity by ADWEA to meet the projected increase in demand in Abu Dhabi, primarily as a consequence of an investment boom that has resulted in a series of mega projects being planned or under construction.
Project Structure and Tender Process
It is against this background that ADWEA has begun a rapid expansion of generating capacity. The new project in Fujairah represents a major part of this expansion. The authority sought expressions of interest in the project, with a final registration date of 25 October 2006. In December 2006, it then issued letters of acceptance to 20 companies that had pre-registered asking them to form consortia to bid for the new scheme.
The proposed plant for which bids were sought was to be built on a green field site under a Build-Own-Operate contract to be awarded by competitive tender. The actual site for the project is Qidfa on the Indian Ocean coast of the emirate of Fujairah. The site is 20 km north of the city of Fujairah and around 120 km from Dubai.
The next stage of the tender process began with the submission of bids in April 2007. From the 20 companies issued with letters of acceptance, four consortia were formed and bid for the contract. These four were International Power in partnership with Marubeni, Suez Energy in partnership with Mitsui, SembCorp in partnership with Sojitz, and AES in partnership with Sumitomo.
Each consortium had already been in negotiation with equipment suppliers, and EPC deals were ready to be signed as soon as the project agreements were finalized. On the power side of the project, these negotiations involved gas turbine manufacturers from Europe and the USA, and other power equipment such as steam turbines and heat recovery steam generators from Europe, USA, South Korea and Japan. Desalination contractors were equally widespread internationally.
In June 2007, ADWEA chose the consortium of International Power and Marubeni as the first-ranked bidder, and this consortium then negotiated a deal with the authority that was concluded on 1 August 2007 with the signing of a 20-year power and water purchase agreement (PWPA) with the Abu Dhabi Water and Electricity Co (ADWEC), a wholly-owned subsidiary of ADWEA.
Following the signing of the PWPA, the consortium and ADWEA set up a new company to own and operate the Fujairah 2 power plant. The company, called the Fujairah Asia Power Company (FAPCO), has an ownership structure under which 60 per cent of the shares are controlled by ADWEA, 20 per cent by International Power and 20 per cent by Marubeni.
The bid from International Power and Marubeni involved an EPC consortium of Alstom, which is responsible for the power generation section of the new plant, and Sidem, which will handle the desalination section of the plant. Sidem, a subsidiary of Veolia Water, will supply one part of the desalination plant while another subsidiary of Veolia Water, OTV will be responsible for the second part, which depends on a reverse osmosis desalination technology.
In addition to the EPC contract, FAPCO has awarded two additional contracts associated with the project. Alstom has signed a 16-year contract to maintain the gas turbines at the plant, while Veolia Water has signed a contract associated with the maintenance of the reverse osmosis portion of the desalination section of the plant. International Power and Marubeni will be responsible for the overall operation and maintenance of the project under a 50:50 joint venture.
Financial closure took place towards the end of 2007. The greater part of the funding secured for Fujairah F2 will be shared by the EPC contractors who will together account for $2.17 billion or approximately 80 per cent of the total. Alstom’s share of the contract is worth $1.36 billion. This is equivalent to a unit cost of $668/kW for the power generation portion of the project. Meanwhile, Sidem’s share of the EPC contract is estimated to be worth a further $750 million. From Alstom’s perspective this is an extremely important project. It is the first project involving the use of its GT26 turbine in the Middle East, and its first IWPP contract in the region.
In addition to electrical and mechanical portions of the works, part of the civil works at Fujairah F2 include marine works. A consortium comprising Lebanon’s Arabian Construction Company and Hong Kong’s Leader Marine Contracting will carry out this work. The marine contract is worth $54 million.
A project of the size and complexity of Fujairah F2 requires careful design if it is to meet its goals. The UAE has a large demand for potable water, a demand that does not vary substantially with the seasons. In contrast peak power demand does depend on the season. During the summer the demand for power is high as a result of high air-conditioning loads. This falls during the winter months as local temperatures fall. As a result of this demand profile the new plant at Fujairah must be able to supply a relatively constant output of potable water while the power output varies from the maximum of 2000 MW to around 900 MW during the winter months
In order to optimize the performance of the plant, EPC contractor Alstom took advantage of what it calls its ‘Plant Integratorà‚â„¢’ approach to design. With gas turbines, steam turbines and heat recovery steam generators for the plant all manufactured within the Alstom group, the company was in a position to choose the best combination of components to suit the demands of the customer, in this instance FAPCO.
Flexibility in the plant design is achieved in several ways. Basic gas turbine combined-cycle plant performance can be adjusted by using gas turbine inlet air cooling, a strategy that increases efficiency when the ambient temperature is high as in the Gulf, or with the introduction of water into the gas turbine compressor inlet air (fogging) which also increases efficiency. Various heat recovery steam generator options are available including drum or once through designs; in the case of a desalination plant a duct-fired boiler may prove the optimum choice. Steam turbine and condenser design can also be chosen to give optimum performance under specified conditions.
Fujairah F2, which is on schedule to be completed in 2010, will be the largest power and water cogeneration plant in the UAE
In the case of Fujairah F2, the overall design must also take into consideration the desalination part of the project. At the IWPP, the desalination plant is made up of two sections, one based on multiple effect distillation (MED) and the other on reverse osmosis (RO). The largest of these, the MED section, takes steam from the combined-cycle plant to generate potable water. The smaller section based on RO is driven not by steam but by power. This combination allows for the optimization of steam and power output from the combined-cycle plant in order to provide constant water production as power demand varies with the seasons.
Optimization is a cyclical process in which each optimized design is further refined until the solution that best matches the customer’s demands, both from a cost and performance perspective, is achieved. In the specific case of an IWPP plant such as Fujairah F2, Alstom’s iterative methodology includes optimization based on the following parameters (among others), taking into account the yearly water/power demand profile:
- Baseline desalination plant performance
- A balance of condensing steam turbines with extraction and back pressure steam turbines
- Selection of pressure level for steam extraction from the steam turbine for use in the desalination plant
- Operational pressures within the heat recovery steam generator
- Proportion of supplementary firing within the heat recovery steam generator
- Ratio of water production from MED versus RO
A cutaway view showing one of Fujairah F2’s power plant groups
In addition to these technical parameters, the value of the products à‚— water and electricity à‚— must be taken into account and balanced to provide the best return on investment.
Fujairah F2 Layout
In order to provide both the power output and the flexibility required by ADWEA, the design chosen for the Fujairah F2 power plant involves three gas turbine combined-cycle blocks incorporating five gas turbines and three steam turbines, a 100 MIGD MED desalination plant based on twelve 8.3 MIGD MED units and a 30 MIGD RO desalination section. This configuration was found to offer the optimum in terms of both flexibility and economy.
The three combined-cycle blocks are not identical. Two are multi-shaft blocks based on Alstom’s KA26-2 combined-cycle units while the third is a KA26-1 multi-shaft block. The KA26-1 multi-shaft block comprises a GT26, 50 Hz gas turbine that is connected directly to a TOPAIR air-cooled generator. A single case STF15C back pressure steam turbine drives another TOPAIR air cooled generator.
The civil contractor for the project was mobilized at the end of January 2008
The other two combined-cycle blocks are based on KA26-2 multi-shaft configurations. In this case, each block has two GT26 gas turbines, each mounted on a single shaft with a TOPAIR air-cooled generator. The exhaust from these pairs of gas turbines is used to raise steam to drive a single, three-case STF30C condensing steam turbine, which has its own TOPGAS hydrogen-cooled generator.
All the gas turbines are provided with inlet air-cooling to raise efficiency under the high ambient temperature conditions frequently found at Fujairah. Each gas turbine also has its own heat recovery steam generator, which is fitted with duct firing to improve flexibility by allowing additional steam to be raised within the steam generator when required.
Simplified flow diagram of one power line (Fujairah F2 Unit 1 & 3)
The twelve MED units of the first section of the desalination plant are driven using steam extracted from the two condensing steam turbines and from the exhaust of the back pressure steam turbine. This provides constant output from the MED units over the year.
The second section of the desalination plant is based on RO. This is driven by power rather than steam and so can be operated independent of steam output. The RO section can therefore be used during the winter to maintain water output when power demand is low but its use can be reduced during the summer when the high voltage grid is requesting the maximum power production
The distributed control system (DCS) used to operate and control Fujairah F2 is based on Alstom’s ALSPA technology. This system will be used to control both the power plant and the desalination plant. Control will be divided into five sections, one for each power block (therefore three), one for the MED plant and one for the RO plant. This will allow the overall plant to be consistently operated and controlled through the same ALSPA control philosophy.
“From Alstom’s perspective this is an important project. It is the first project involving the use of its GT26 turbine in the Middle East, and its first IWPP contract in the region”
Grid connection is via a gas-insulated switchgear substation that is already at the site. This was installed by the Abu Dhabi grid company, Transco, a wholly owned subsidiary of ADWEA, to provide connection for the Fujairah F1 power plant already at the site. The latter will have a net generating capacity of 760 MW and water output of 100 MIGD when the current extension is completed in 2009.
This substation links into a 400 kV network that is part of the Abu Dhabi grid system and the Emirates National Grid. However additional 400 kV links are being built between Fujairah and Sweihan in Abu Dhabi, and to Ras Al Khaimah and Sharjah in order to transmit the additional power from the new plant to the load centres.
The prime movers for the three combined-cycle blocks at Fujairah F2 are five of Alstom’s GT26 gas turbines. At the IWPP, these will be capable of dual fuel operation, burning natural gas under normal circumstances, with the capability of operating on liquid fuel if the gas supply is interrupted.
The GT26, and its 60 Hz variant the GT24, are the latest of Alstom’s large power plant turbines. The GT26 has a rated output in open cycle of 288.3 MW and an efficiency of 38.3 per cent. The unit, however, is designed for combined-cycle use, and under these conditions when closely coupled with a steam turbine it can achieve efficiencies approaching 60 per cent. Typical performance data for both the KA26-1 single-shaft configuration and the KA26-2 multi-shaft configuration are presented in Table 1 below.
The design of the GT26 incorporates a 22-stage subsonic compressor that takes inlet air and compresses it before introducing it into the unit’s combustor. In the case of the Fujairah plant the inlet air is first cooled in order to gain operational efficiency before entering the compressor. The combustion system in the GT26 is divided into two, sequential stages; a strategy that, according to Alstom, allows it to achieve high efficiency without having to resort to extreme high temperatures. This, in turn, helps control NOx emissions.
The first combustion stage is an annular combustor with 24 retractable burners (this is designated the EV combustor by Alstom). Fuel and compressor air are premixed before entering these combustors where combustion of the mixture takes place. The hot exhaust gases then pass through a single blade, high-pressure turbine section before entering the second (sequential EV or SEV) combustor. As with the first, this is an annular combustor with 24 burners in which the injected fuel ignites spontaneously when it mixes with the hot exhaust gases from the first combustor. Exhaust from the second combustor then enters the four-blade,low-pressure turbine section
“In order to optimize the performance of the plant, Alstom took advantage of what it calls its ‘Plant Integrator’ approach to design”
Alstom’s data show that this arrangement of combustors allows the temperature of gases exiting the first combustor to remain constant from between 100 per cent and 30 per cent load, while the temperature of the gases exiting the second combustor starts to fall once load drops below 40 per cent. Gas turbine exhaust gas temperature is therefore maintained at a roughly constant level between 100 per cent and 40 per cent load, and this results in good part load combined-cycle performance. Alstom claims a relative efficiency of 87.5 per cent at 40 per cent load, compared with a nominal 100 per cent efficiency at 100 per cent load.
The constant combustion and exhaust gas temperature profiles over a wide range of gas turbine operating conditions also make it easier to optimize NOx emission performance. Measurements on a GT26 at a test power plant in Birr, Switzerland in 2005 showed that these were well below 25 vppm between 100 per cent and 40 per cent load.
The GT24/GT26 turbines have proved popular for combined-cycle applications, and at the time of the announcement of the Fujairah F2 order there were 81 operating around the world. Over a third of these were in the USA and there were significant numbers in both Spain and the UK. The majority were single-shaft KA26-1 units with a small number of multi-shaft combined-cycle plants and some operating in open cycle.
HRSGs, Steam Turbines and Generators
The five gas turbines at the Fujairah F2 will each be equipped with its own heat recovery steam generator (HRSG). All five boilers will be identical and are supplied by Alstom. Each is fitted with duct firing, which will be used to supplement the steam output when electrical load is reduced during the winter in order to supply sufficient energy to drive the MED desalination units.
Two different steam turbines will be utilized at Fujairah F2. The two KA26-2 multi-axis combined-cycle blocks will be equipped with STF30C three case floor mounted condensing steam turbines. The KA26-1 multi-shaft, in contrast, will be fitted with a STF15C single case back pressure steam turbine, again floor mounted. Both are designed specifically for combined-cycle operation
The STF15C will provide up to around 150 MW of power at Fujairah F2. The back pressure steam turbine provides exhaust steam for the MED desalination units. Meanwhile the two STF30C condensing steam turbines will each provide up to 370 MW depending on the unit load. These two turbines will be provided with steam extraction points from which steam can be taken to drive the MED desalination units. As with all the company’s steam turbines, the units for Fujairah F2 have welded rotors, separate high pressure and intermediate pressure casings, and single bearing supports between turbine casings
As with the steam turbines, two different types of generators are also being used at Fujairah F2. The five gas turbines and the back pressure steam turbine are each equipped with one of Alstom’s TOPAIR generators, which is directly coupled to the gas turbine on the same shaft.
The TOPAIR generator is a totally enclosed, water-to-air cooled generator. In this design, stator windings are indirectly cooled while the stator core and the rotor are radially cooled.
The other generators at Fujairah F2 are based on Alstom’s TOPGAS hydrogen-cooled design. This uses a hydrogen-to-water cooling system for higher efficiency, enabling larger power handling. As with the TOPAIR units, stator windings are indirectly cooled while the stator core and rotor are cooled directly.
Desalination at Fujairah F2 will be performed using two different technologies, multiple effect distillation (MED) and reverse osmosis (RO).
The first technology is a thermally driven distillation process, which utilizes steam from the combined-cycle plant, while the second, in contrast, is electrically driven.
The combination of the two different technologies provides the most economical solution in order to allow the potable water output to be maintained as the power output varies with the seasons
MED is carried out in a cascaded series of cells called ‘effects’. Each cell contains horizontal bundles of tubes into which steam is introduced while cold seawater is sprayed over the tubes from the top of the cell. Steam from the combined-cycle plant is fed into these horizontal tube bundles in the first cell. This steam causes evaporation of water from the seawater and at the same time condensing the steam within the tubes in the cell to produce pure distillate. The water produced from the condensation of steam within the tube bundles is collected, as is the brine that emerges from the bottom of the cell.
Meanwhile the steam generated within this first cell is fed into horizontal tube bundles in a second cell where the whole process is repeated, but with slightly cooler steam and with the pressure within the cell maintained at a lower level than in the first.
By repeating this in a series of cells or ‘effects’, most of the heat energy contained in the steam from the power plant can be exploited to evaporate water from seawater to provide distillate, leading to a highly efficient process. Steam from the last cell in the series is condensed using a seawater-cooled condenser.
The Fujairah F2 project has a tight schedule, with all three plant groups due to be commissioned in 2010
To enhance the flexibility of the desalination operation further and allow optimum output when power demand is low, the new plant at Fujairah will also be equipped with a 30 MIGD RO unit. This is also the responsibility of Sidem, and will be supplied by its sister company, OTV.
Osmosis is a natural process whereby water (or other solvents) migrate across a membrane in order to equalize solution concentrations either side of the membrane. If, as in this case, one side of the membrane is pure water while the other side is brine, water will try to cross from the pure water to the brine since this is the more concentrated solution. If, however, the concentrated solution, the brine or seawater, is put under pressure then the natural process is reversed and water travels from the brine across to membrane to the pure water side. Thus by this process of ‘reverse osmosis’ drinking water can be produced from seawater.
Since RO requires power, it is relatively more expensive to operate than MED. However it offers a good method of supplementing water output in the winter when power demand is low, since power generated from the combined-cycle plant can be diverted from the grid to the RO unit.
Following the conclusion of an agreement between ADWEA, International Power and Marubeni in July 2007 and the finalization of the EPC contract, project closure took place in late 2007 and notice to proceed was issued on 18 December 2007. Meanwhile work started at the site on 1 November 2007.
The civil contractor for the project was mobilized at the end of January of this year and the boiler contractor was mobilized at the end of October 2008. Electrical and mechanical contract mobilization is expected to occur in January 2009. This represents a tight schedule since it allows little more than a year until the first plant group is due to be commissioned in the first half of 2010. The commissioning of the second and third plant groups are also due in 2010.
Allied to the IWPP project itself are three transmission schemes. The first involves construction of a new 240 km gas pipeline from Taweelah in the Emirate of Abu Dhabi to Fujairah to supply the plant with natural gas. The gas supplier, Dolphin Energy is developing the project and awarded the contract to design and build the pipeline to Stroytransgaz of Russia. Work began at the beginning of 2008 and is due to be completed during the third quarter of 2010.
With the development of the Fujairah F2 project, the transmission facilities for power and water are being upgraded to extend the region’s gas, power and water network infrastructures.
Fujairah 2: A welcome capacity addition
When it is completed, Fujairah F2 will be the largest power and desalination plant in the UAE. With a potential output of 2000 MW of power and 130 MIGD of potable water it will provide an important boost to capacity, particularly in the Northern Emirates where Fujairah is situated.
This boost is timed to coincide with an expected sharp rise in demand as a result of a building boom in Abu Dhabi. How this will develop in the light of the economic crisis of 2008 remains to be seen but it appears likely that the region will still demonstrate strong growth over the medium term, in which case the additional capacity provided by Fujairah F2 will play an important role in maintaining that growth.
ABU DHABI’S POWER DEMAND
Abu Dhabi is the largest of the seven emirates à‚— Abu Dhabi, Dubai, Sharjah, Fujairah, Ajman, Umm al-Quwain and Ras al-Khaimah à‚— that make up the UAE. It covers around 90 per cent of the total land area of the UAE and has a population of around 1.5 million, or roughly one third of the total UAE population. The economy of the UAE is founded primarily on oil and gas, though diversification has begun in order to try to reduce the reliance on fossil fuel sales. Abu Dhabi is the richest oil emirate in the UAE, followed by Dubai.
Demand for both electricity and water has grown rapidly in the Emirate of Abu Dhabi over the last ten years. In 1998, when the sectors were reorganized with the creation of ADWEA, installed generating capacity was 3343 MW (see table below). This has risen steadily so that by 2007 the total installed capacity was 8367 MW. This rise in generating capacity has been accompanied by a switch from state-owned to IWPP-based production, with both the construction of new projects and the shifting of existing projects into private sector ownership. As a consequence around 8000 MW of the total generating capacity at the end of 2007 was provided by IWPP projects.
Desalination capacity has risen similarly over the same period. In 1998, total dependable desalination capacity was 212.4 million imperial gallons/day (MIGD). By the end of 2007 this had risen to 629.2 MIGD.
While the expansion in the power and water sector is ostensibly based on private sector development, the state still retains a large stake as a result of the structure of the projects. Since 1998, there have been seven new IWPP schemes launched, including Fujairah F2. These have all involved the establishment of individual power companies to own the projects and these companies have had a joint ownership structure in which 60 per cent of the shares in the company are controlled by ADWEA and the remaining 40 per cent belong to the foreign partners in the project. Thus the state always retains a controlling share.
The need for this large addition in capacity can be found in the investment plans for Abu Dhabi. The conjunction of changes in land ownership laws and the availability of enormous quantities of surplus revenue from oil sales has led to an investment boom in the region.
The Abu Dhabi Water and Electricity Co (ADWEC), a wholly-owned subsidiary of ADWEA, which purchases all the power from IWPP projects and is the single seller of water and power in Abu Dhabi, has identified more than $172 billion in investment in what have been designated ‘mega’ projects in Abu Dhabi, which will have to be supplied with power and water. This represents more than twice the gross domestic product (GDP) of Abu Dhabi in 2005.
The Fujairah F2 project has a tight schedule, with all three plant groups due to be commissioned in 2010
Some of these projects will be residential, others for mixed use. Much uncertainty remains in both timing and scale of many of the schemes. It should be noted however that the capacity for the mega projects is in addition to the capacity required to meet the natural growth in demand.
Peak demand is likely to lag these developer predictions but even so, according to the most likely scenario developed by ADWEC, the peak demand from these new projects will exceed 2000 MW by 2010, reach close to 3300 MW by 2012 and be around 4525 MW by 2014. When this is added to the existing demand and its expected growth, total peak demand is predicted to be 8276 MW in 2010, 11 706 MW in 2012 and 13 868 MW in 2014. This can be compared with peak demands in 2006 of 4790 MW and 5286 MW in 2007.