On 28 April, 1999, the Al Taweelah A2 natural gas-fired power generation and water desalination project in Abu Dhabi reached financial closure. This project is the first project financing in the United Arab Emirates (UAE), and the first project financing of an independent water and power project (IWPP) in the world. It forms an integral part of Abu Dhabi’s privatisation programme to restructure its entire water and electricity sector, which began officially in 1996.

Located on the coast of the Arabian Gulf approximately 65 km northeast of Abu Dhabi, the project consists of a 710 MWe natural gas-fired combined cycle power plant and water desalination facility capable of producing 50 million gallons of water per day. Both power and water from the plant will be sold to ADWEA under a 20-year power and water purchase agreement.

The $600 million 17-year project financing was lead arranged by Barclay’s Capital, and joint-arranged by a diverse group of international and regional banks, including: Abu Dhabi Commercial Bank; Abu Dhabi Investment Corporation; ANZ Investment Bank; Gulf International Bank; Union National Bank of Abu Dhabi; NordLB; Banque Paribas, Societé Generalé; and WestLB.

The Abu Dhabi government holds a 60 per cent stake in the project company, and CMS Energy holds the remaining 40 per cent. The government intends in due course to sell some or all of its stake in the project.

The original bid process was for a 580 MWe plant. According to Victor Fryling, the president and chief operating officer of CMS Energy, CMS advised the Abu Dhabi government that it could provide an extra 130 MWe at minimal extra cost. The Abu Dhabi government was interested in this expansion, but advised CMS Energy that it had to win the bid based on the original conditions. This CMS Energy did, and subsequently, the project expansion was accepted by ADWEA.

Emirates CMS Power Company, a local company set up to own the project, has awarded an engineering, procurement and construction contract for the project to a consortium of Siemens of Germany and Hanjung of Korea. A limited notice to proceed was issued to the contractor in October 1998, to allow design work to begin. Piling of foundations is currently underway at the site, with the first gas turbine scheduled to operate by May 2000, and full commercial operation scheduled for August 2001.

Sheikh Diab bin Zayed Al Nahyan, chairman of ADWEA, said that Abu Dhabi was looking at setting up a second independent water and power project.

Technical details

The power island will consist of three Siemens V94.3A gas turbine generators, three Hanjung heat recovery steam generators, and two Siemens NG 90/90 steam turbine generators. The desalination island includes four Hanjung multistage flash evaporators, pumping, storage, remineralisation and related systems and equipment. The generated steam is expanded in the steam turbines and is afterwards used for heat input to the desalination plant.

The gas turbines are dual fuel units, with natural gas as the primary fuel, and fuel oil as the backup fuel. Each turbine consists of 4 turbine stages, 17 compressor stages, and one variable guide vane row, and includes a one-ring combustion chamber with 24 burners. Turbine rated speed is 3000 rpm. The Siemens type TLRI 115/52 generator is rated at 218 MVA, 15.75 kV, 0.85 power factor, 50 Hz.

Each HRSG has a rated total heat capacity of 440 MWth, with a steam flow of 150.5 kg/s, with natural gas supplementary firing.

Each steam turbine is rated 111.28 MWe, 3000 rpm, with inlet steam conditions of 520°C, 66.5 bar, and 169.5 kg/s. The facility is equipped with 2 x 50 per cent titanium-tubed dump condensors, 3 x 50 per cent turbine bypass stations, once-through seawater cooling, and feedwater system. The associated generator is Siemens Type TLRI 100/36, rated 131 MVA, 10.5 kV, 0.85 power factor, 50 Hz.

The rated secondary voltage of the generator step-up transformer is 420 kV. In-plant electrical equipment is designed for 11 kV, 420/230 kV or 220 V(DC). Two 100 per cent emergency diesel generators are provided, each rated at 1.6 MVA, 0.4 kV, 50 Hz.

Each of the four desalination evaporators is approximately 85.5 m long, 26.8 m wide, and 7.6 m high, and consists of 16 heat recovery stages and 3 heat rejection stages arranged in a cross tube configuration. There are 3500 corrosion resistant tubes per stage in the heat recovery section, and 2855 per stage in the heat rejection section. The maximum output of each evaporator is 12.85 million gallons per day. The design top brine temperature is 108°C, with 18°C seawater and 27°C cooling water at heat rejection section inlet.

The power plant is designed to operate between 30-100 per cent base load. Within the whole operating range, sufficient steam can be extracted from the power plant to operate the desalination plant at 100 per cent output.