In 1998, the government of South Australia knew it would need to act quickly if it was to stave off power shortages. It decided to call on the private sector – the result was Pelican Point, a 500 MW combined cycle project being developed on a fast track basis by National Power.
Figure 1. Work starts early at Pelican Point
In February last year the government of South Australia announced it had awarded a contract to build a new 500 MW power plant at Pelican Point in Adelaide’s northwestern suburbs. It was an important announcement for a State whose debts were too high to fund a new power plant.
The plant is being built in time to avoid looming power shortages. Under the contract, National Power (i.e. its new international successor company International Power) will build the plant so that power becomes available in stages. Once complete, the plant will increase South Australia’s generating capacity by 20 per cent.
Figure 2. Arrival on site of generator for the first gas turbine in January this year
Commenting on the award, Ed Metcalfe, project director for National Power noted: “It was a very fast track bidding process. IPP bids can often drag on for a long time but the State was aware it was short of power and wanted to identify, as soon as possible, who was prepared to build a power station; and offer them the ‘opportunity’ to build it. It was not in essence a contract to build Pelican Point but was really ‘an opportunity’ to bid. The State had identified a site although this site was not compulsory. National Power had in fact identified two or three possible sites, the best of which was Pelican Point.”
The opportunity to build was part of a ‘package’ being offered by the government. In addition, the State was also offering: development approval which meant that the project developer would not have to gain site approvals; a contract through to 2005 with the state gas company Terra Gas Trader for enough gas to fuel 250 MW of plant; and a short term retail contract for 200 MW of output from the plant.
Figure 3. The switchyard and start of transmission line from the site
This type of package was fairly unique for South Australia and came about due to the transformation that had been going on at the time in the State. South Australia was in the process of preparing to sell off its generation assets; its gas company, Terra Gas Trader; its transmission business, Electranet; and its distribution and retail business. It also planned to sell Synergen, a company which owns all the open cycle plant in the State. Initially the opportunity to build the Pelican Point power station was to be included in the sale of Synergen.
However, the privatization process was stalled when the liberal government met opposition to the privatization. Nevertheless, the government still recognised that there was a power shortage in the State and that Pelican Point had to be built quickly.
Figure 4. Panoramic view of the site. Construction of the plant is well underway with nearly all of the land-based civil works completed
Metcalfe explained: “The opportunity to build Pelican Point was pulled out of Synergen and offered up through this bidding process as an opportunity for the private sector to come and build.”
The government first issued an invitation to bid for the opportunity to build a power project in South Australia in September 1998. Some 24 companies, including National Power, expressed an interest in the bid. From these 24 companies, 16 companies were shortlisted to attend a bidders conference on November 16, 1998. This was the start of a bidding opportunity to see who would offer the State the most money for the right to build a power station. At this stage an indicative bid was required which had to be submitted by the middle of December 1998.
Figure 5. Due to high daytime temperatures, some concrete pouring operations took place at night
From this indicative bid, a further shortlisting process took place from which four companies were chosen to submit final bids. Final bids were submitted on January 22, 1999. National Power won the bid and signed the contract to build the power station on February 3, 1999.
National Power’s bid was to build a plant of 500 MW at Pelican Point. As part of the package it received a 20-month retail contract for 200 MW of power plus a gas contract for the equivalent of 250 MW of output. “Development approval meant we could start straight away and the sale of the required land at Pelican Point was part of the State’s commitment,” added Metcalfe.
The total plant will cost an estimated $250 million, and is being built on a project finance basis. National Power will provide 40 per cent of the funds in equity with the remaining 60 per cent provided as debt finance from four banks: Royal Bank of Scotland, ANZ, Société Génerale and CBA.
Obtaining loans from the banks went without a hitch even though there were none of the usual guarantees and long term agreements that are associated with more traditional IPP projects.
According to Metcalfe, the plant is the most merchant plant in Australia and at the time was the most merchant of National Power’s plant. “When we went to the banks, we only had gas for 250 MW of plant although we were building a 500 MW power station. There was no long term fuel agreement, which caused the banks a slight concern. Also there was no long term power purchase agreement – we had a 20-month contract for 200 MW of the output. The banks’ two main concerns were the market and a small technical concern of having to drill a gas pipeline under the river.”
There were no concerns over the plant design or choice of gas turbine. The power station is essentially the sister station of one built at Deeside in the UK and another in Turkey. This gave the banks the confidence that National Power had the engineering experience to build the plant successfully.
The banks also had enough confidence in the size of the gas market to believe that sufficient gas would be available. They also saw that it was a good market in which to build since there was a shortage of electricity in the State and power prices were higher than in neighbouring states like Victoria and New South Wales.
Metcalfe noted: “Since we have established the project financing we have repaid the banks’ confidence in us by successfully installing the gas pipeline, and sourcing the gas for the other 250 MW of the plant from AGL.”
AGL has also agreed to take much of the electricity output from the plant. Metcalfe added: “While it is a merchant plant, we now have sensible gas contracts and are well hedged for the first three years operation of the plant.”
Fast track CCGT
The contract called for 150 MW to be available by November 2000, with this output increased to 250 MW by November 2001. The government’s growth curves show that a further 250 MW would be needed by 2004.
The main load occurs in the summer months – caused by air conditioning to combat temperatures which can reach 40°C. Peak load in Adelaide is growing at 4.9 per cent per year compared to an average of 2.4 per cent in the rest of the year. In fact this summer saw rolling blackouts due to power shortages.
Assessing the situation, Metcalfe says: “We looked at the bid requirements and clearly the invitation was for someone to be bidding an open cycle machine of about 150 MW to be ready by November 2000. This would then have to be converted to combined cycle by November 2001. The economics of this, however, were not favourable and National Power therefore based its bid on building 500 MW of plant as fast as possible.”
In order to have the power available by the government deadline, National Power is taking an unusual staggered approach to the construction of the plant.
The company is building a 2 + 1 configuration where the power plant will consist of two ABB Alstom Power GT13E2 gas turbines; two heat recovery boilers and one steam turbine. To have the power available by November 2000, the first gas turbine will be installed in open cycle with a blast stack.
Gas turbine No. 2, its associated HRSG, and the steam turbine are being built in parallel. This 1 + 1 unit will be available by late December 2000. Boiler No. 1 will be built at the same time. Final commissioning of the whole plant i.e. removing the blast stack and connecting gas turbine No. 1 to the HRSG and steam turbine to complete the 2 + 1 configuration; will take place by the end of March 2001.
The plant is designed with strict environmental standards in mind. For example, the cooling water discharge from the power station has to be within 2°C of the sea water temperature within a 50 m radius of the discharge point. This compares to the 3°C World Bank standard. Noise standards are also much stricter than Australian standards since it is in a fairly quiet area. This requires the use of acoustic enclosures for gas turbines and particularly the steam turbine.
The ground level concentration of nitrous oxides are limited to 60 per cent of the Australian standard. “This means the plant has to be 40 per cent better than the Australian standard and much better than any other plant in the area,” noted Metcalfe. This was an important factor in the selection of the GT13E2 gas turbines.
The $200 million turnkey contract to supply the turbines and build the plant was awarded to ABB Alstom Power in April 1999 by National Power South Australia Investments Ltd, a subsidiary of National Power plc.
The combined cycle plant design consists of a KA13E2-2 multi-shaft unit using two GT13E2s coupled to a totally enclosed air-water cooled generator. The exhaust of each turbine is fed to a heat recovery boiler which is connected to serve a common dual pressure steam turbine.
The generators are placed on the cold side of the turbines feeding three step-up transformers. When operating on natural gas, no water injection is needed to achieve the specified emission limits.
The GT13E2 gas turbine uses ABB Alstom Power’s lean pre-mix dry low NOx, EV (EnVironmental) combustion system, successfully adapted to an annular combustor from the original GT13E. The upgrade to an annular combustor also allowed for an increase in turbine inlet temperature from 1070°C to 1100°C and an increase in compressor ratio from 13.9:1 to 15:1.
The turbine is based on a 21-stage compressor and a five-stage turbine arranged on a common rotor. The single annular combustion system features 72 EV burners arranged in four rings around the turbine. The symmetrical arrangement results in a uniform temperature distribution at the inlet, effectively reducing temperature variations typically associated with can-annular combustors.
The gas turbines have a rated output of 165.1 MW, and a simple cycle efficiency of 35.7 per cent. When running on natural gas, NOx levels are kept below 25 ppm.
Pelican Point is expected to have a combined cycle efficiency in excess of 52 per cent and an extremely good part-load efficiency down to 75 per cent load.
In tandem, the turbines can run in continuous or two-shift operation to give the plant the flexibility to match supply with demand. This configuration requires short startup times. The turbines and HRSGs are therefore started independently from the steam turbine through steam bypasses.
The gas and steam turbines and the HRSGs and water cycle equipment will be installed outdoors although some of the main water/steam cycle components are covered by enclosures.
The floor mounted machine sets are supported on a single foundation block and are covered by weatherproof enclosures. The electrical and control building is located next to the machine sets.
Construction of the plant is well underway with nearly all of the land-based civil works completed. Both gas turbine-generators have arrived on site ahead of schedule and construction has started on the two HRSGs. Buildings for the control room, administration and workshop have also been completed.
Construction works for the seawater cooling is underway.
Gas comes from a gas pipeline which passes about 1.5 km from the plant on the other side of the river. This meant that the plant constructors had to drill under the sea in order to install the gas pipeline. This technically challenging work has also been achieved.
The main switchyard for connecting to the 275 kV grid is about 2.5 km away, and most of the transmission line to connect to this is now complete.
The plant is on schedule to commission the first 150 MW in November. The rest of the plant will be commissioned at incremental output levels with full commissioning scheduled for March 2001.