Mt Stuart is a 414MW peaking power station situated 12km south of Townsville, in the suburbs of Stuart in Queensland, Australia. It supplies electricity to 240,000 households and is the largest peaking power station in Queensland.
The plant was commissioned in January 1999. It was originally owned by AES Corporation, which was acquired by Origin Energy in 2003 for $93m.
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Origin Energy expanded the plant’s capacity by adding a third turbine in November 2009.
Queensland plant history
The plant originally commenced operations with a 288MW capacity.
At the time of acquisition, power generated by Mt Stuart Power Station was being supplied under a power purchase agreement (PPA) to the state-owned entity Enertrade. The plant used to operate only on request by Enertrade to meet the electricity demand in North Queensland.
In 2006, Origin Energy terminated the PPA agreement with Enertrade.
As a part of Origin’s strategy to increase the company’s generation capacity to 2,800MW in 2010, it was decided to expand the plant’s capacity by 45% to 414MW.
The Australian Government office of Coordinate-General for remote indigenous services approved the expansion which would provide additional power security and strengthen power supply in Queensland. Origin Energy invested about A$110m in the expansion project, which took 18 months to complete.
The expansion project also involved laying of a new transmission line between Townsville South and Townsville East substations.
Power station details
Mt. Stuart has three gas turbine generators. Two of these are of Mitsubishi make and have been functioning since January 1999. They were originally fuelled by kerosene and were eventually converted to gas turbines.
The third turbine is a 126MW Frame 9E gas turbine delivered by GE. It weighs 380t.
Natural gas is supplied through a pipeline from Origin Energy’s coal seam gas resources in Queensland.
The gas turbines are designed based on combustion engines used in automobiles.
Air and fuel are mixed and ignited inside the turbine. Gas produced during the process is compressed in the compressor and released with force to cause the turbine-rotor to rotate. The turbine is connected to the generator which also rotates along with the turbine.
The generator is equipped with an electro magnet. The magnet produces electricity when it comes in contact with the mechanical energy created due to rotation.
This electricity is carried to a step-up transformer which boosts the current and further transmits it to the national grid for distribution.
Grid network
Power generated by the first two generators is transmitted to the national grid by a double circuit, 132kV transmission line. Power from the new 126MW generator is transmitted via a newly laid 750m single circuit 132kV transmission line between Townsville South and Townsville East substations.
Transmission lines
The newly laid single circuit transmission line from Townsville South is connected to a newly built 66kV substation in Townsville East. It passes through 2ha site in Townsville Port.
The overhead fibre optic wires are supported by a series of steel poles, each measuring 36m tall.
Contractors involved with Mt Stuart power station
Leighton Contractors of Australia was the engineering, procurement and construction (EPC) contractor of the 126MW expansion project. The company constructed the new administration building, auxiliary plant and high voltage systems.
The expansion project was managed by Queensland’s engineering and management services company Maintain Power. The company’s scope of work included importing the gas turbine generator, installing and commissioning of balance of plant and overall supervision of the project.
An environmental impact statement (EIS) was carried out for the installation of a new transmission line for the third turbine. The main contract to construct this line was awarded to Maunsell Australia (now AECOM) who in turn appointed Powerlink to analyse the review of environmental factors (REF).
