The 435 megawatt (MW) combined-cycle Tallawarra Power Station is the first major gas-fired generation development for TRUenergy in New South Wales. The plant is currently Australia’s most efficient power plant, producing more electricity per unit of fuel burnt than any other plant in the country – operating at nearly 60 per cent net thermal efficiency.

The plant, constructed at the site of the former coal-fired Pacific Power generator, is set to help TRUenergy meet its expanding retail base electricity demands. The New South Wales Government decommissioned the Pacific Power plant over a ten year period, with operations finishing in 1989.

The plant is connected to the local distribution 132 kilovolt (kV) grid, which is interconnected to the New South Wales 330 kV grid via substations. Gas for the power station is being supplied via Jemena’s Eastern Gas Pipeline.

Construction

TRUenergy awarded Alstom an engineering, procurement and construction contract for the power station. The contract covered the delivery of a KA26-1 single-shaft combined-cycle unit and a long term service contract to carry out scheduled maintenance and provide operational support for the project.

Alstom began construction of the Tallawarra Power Station in November 2006, marking the fifth combined-cycle power station that the company has constructed in New South Wales in the last 30 years.

Tallawarra provided approximately 400 jobs during construction and now employs 27 full-time operational staff.

The power plant consists of one GT26 gas turbine, one 125 MW steam turbine, a condenser, step up transformers, plant control systems, civil works and balance of plant (associated infrastructure). The GT26 gas turbine was chosen for the plant due to requirements for high operational flexibility, availability and fast-start capability. The gas turbine has a rated output of 288 MW, providing an additional 7 MW compared to previous GT26 models. An improved compressor provides increased mass flow and better seals reduce the leakage of air.

The GT26 is connected to a hydrogen-cooled generator and a steam turbine. Exhaust gas leaving the gas turbine is fed into a triple pressure reheat heat recovery steam generator (HRSG), which generates the steam that is fed into a triple casing steam turbine to generate an additional 160 MW. The steam turbine is a three-casing design with high pressure, intermediate pressure and low pressure sections connected to the generator via a self-synchorising clutch. The steam turbine has a direct seawater cooled condenser, which uses water from Lake Illawarra.

Tallawarra also has power augmentation in the form of an evaporative cooling system at the inlet of the gas turbine, as well as a high-fogging system. This enables TRUenergy to generate and sell an additional 20 MW at peak production times.

The sequential combustion feature of the GT26 means that the plant has high part load efficiency. Emissions are maintained at low levels when the turbine is running at low load. This also means that the plant has very high flexibility. The power station, although operating predominantly in base load, is designed for daily start-stop operation and is able to reach full load from hot conditions in one hour.

Environment

The gas-fired power station produces low cost, environmentally responsible and reliable power. Because Tallawarra is Australia’s most efficient fossil fuel power station, it is also Australia’s cleanest, releasing fewer carbon emissions per unit of fuel burnt.

The power station has a significantly smaller footprint than the original coal-fired power plant that used to be on the site.

TRUenergy Managing Director Richard McIndoe said “This $430 million investment in super efficient gas generation emphasises TRUenergy’s commitment to transform its generation portfolio and reduce its carbon emissions intensity by one third by 2020, which is the first stage of our Climate Change strategy.

“TRUenergy Tallawarra is Australia’s most environmentally efficient, large-scale gas-fired power station, and most importantly, produces 65 per cent less carbon dioxide emissions than the average Australian coal-fired plant.”

An onsite water management system ensures that the quality of water entering nearby Lake Illawarra will be better than average for the local catchment area. In addition, extensive landscaping of the site helps the power station to blend in with its surroundings, reducing its visual impact.

“Efficient gas-fired generation will be a key part of the solution for our business, and for all Australians if we are to maintain our current standard of living while we transition to a lower carbon environment,” said Mr McIndoe.

Securing NSW energy needs

Following its completion, Tallawarra is now producing enough electricity to power around 200,000 homes.

At the power station’s opening on 18 March 2009, New South Wales Premier Nathan Rees said that the extra generation capacity was a welcome boost to the state’s energy supplies. He said that the power station would reduce the risk of power shortages at times when demand for electricity suddenly increases.

Mr Rees said “The station is one of Australia’s most environmentally efficient gas-fired power stations.

“The New South Wales Government supports any proposal that will provide further security for our energy needs,” Mr Rees said.