Gas-fired Combined Cycle Power Plant
The Tamar Valley Power Station is a 210MW LNG-fired gas turbine combined-cycle power plant, located at Bay Bell near George Town on the Tamar River in Tasmania. It was commissioned in October 2009 after 24 months of construction.
The power station is owned and operated by Aurora Energy, the government-owned power distributor and largest energy retailer in Tasmania, under the trade name Aurora Energy Tamar Valley (AETV Power).
The Tamar Valley power plant is the first privately owned project in Tasmania. The project was intended to diversify power generation and ease the pressure on the state’s hydro electric dams, which are prone to drought conditions. It is also expected to optimise the economic benefits of the Tasmanian underwater gas pipeline laid in the Bass Strait. The power plant is supplemented with a 180MW open-cycle back-up and a peaking plant.
The project required an investment of approximately $451m. The Tasmanian Government is considering selling the plant as it has not been able to break even. The announcement in this regard was made in June 2011 and a public consultation is expected to be completed by mid-August 2011.
The Tamar Valley Power Plant is the single largest generating plant in Tasmania. It consists of a base load combined cycle unit with 701DA gas turbine supported by two 140MW generators. It has a Nooter-Eriksen heat recovery steam generator (HRSG) and a hybrid cooling tower designed by Hamon. The HRSG is capable of producing 420tph of high pressure steam.
The supplementary peaking plant comprises three pre-existing 40MW Pratt & Whitney FT8 Twin Pac gas turbinesm generating 120MW, and a new Trent 60 wet low emissions gas turbine.
The LNG is transported via a 305km-long undersea pipeline installed in the Bass Strait.
The plant also houses a water treatment plant whose output is used for cooling the towers of the main plant and the peaking plant.
The Tamar Valley project was originally undertaken by Alinta Energy (now known as Red Bank Energy) in October 2006 after it signed a power supply agreement with Aurora Energy. In March 2007, Alinta Energy bought the 105MW Bell Bay Station from Tasmania Hydro for $75m to add as a back-up plant to the planned Tamar Valley Power Plant.
Soon after the preliminary works began in August 2007, the assets of Alinta Energy, including the Tamar Valley Power Station, were acquired by Babcock and Brown Power.
Babcock and Brown decided to sell the plant during the economic crisis in 2008. The Tasmanian Government took over the plant in September 2008 and transferred the ownership to Aurora Energy.
Aurora Energy consequently assumed the responsibility of completing the construction, installation and commissioning of the plant.
In January 2009, AETV Power signed an agreement to purchase the gas, electricity and commercial operation contracts that were originally awarded by Alinta Energy in relation to the Tamar Valley power plant.
The main contract for the plant’s development was awarded to United Group. The company installed the Rolls-Royce Trent 60 gas turbine in the pre-existing plant. It was responsible for the design, supply, and installation and commissioning of the balance of plant equipment, and erection and commissioning of 210MW combined cycle power at the adjacent site.
United Group also constructed the water treatment plant and erected the hybrid cooling tower. The firm appointed AC Engineering Services as the mechanical construction superintendent.
Site preparation, civil design and feasibility studies for the two 140MW units were conducted by GHD under a contract awarded by Alinta. The earthworks contract was awarded to Shaw Contracting. The civil contractor was Hazell Brothers.
Other contractors involved in the project were Russel Smith Electrical, Contact Electrical, Haywards, BLH Group of Companies, Tasmanian Electrical Services, Cooling Tower Contractor, and Specialist Access and Hire.
The combined cycle gas turbine and the open cycle Trent 60 gas turbine were supplied by Mitsubishi and Rolls Royce respectively. The corresponding orders were placed in 2007 by Alinta Energy.
The existing 110kV transmission line was upgraded to 220kV by TRANSEND and Emcor Services.
Transmission cables were supplied by WW Cables on contract basis for United Group. The cables are 1,060m long and are of type IC 800mm2 22kV.
The aquatic monitoring of the thermal water discharge from the plant into the Tamar estuary and the Donovans bay was done by Aquenal.
Minter Ellison acted as the financial advisor to Aurora Energy for financing the purchase of the plant, while Allens Arthur Robinson negotiated the deal and the purchase agreement on behalf of the Tasmanian Government.
The Tamar Valley plant has a total generating capacity of 390MW including the peaking plant.
The output is equivalent to 14% of the total generating capacity of Tasmania.
Power produced by the plant is transmitted to George Town substation via a new 220kV transmission line.
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