By Sarah MacNamara, Assistant Editor, Pump Industry Magazine
Some of the largest pumps in Australia can be found at power stations, with many of them at gas-fired power stations – generating the country’s electricity and playing an important role in the transition to clean energy.
Natural gas is the third largest energy source in Australia and when used to generate electricity, has been found to emit around half of the emissions of coal. Gas is expected to be vital as Australia strives towards net zero emissions by keeping the power system stable in the transition to clean energy.
Gas-fired power stations burn gas to produce electricity, and there are two main types of power stations to do this – open cycle and combined cycle.
At open cycle power stations, natural gas is burned to create a pressurised gas, which spins the blades of a turbine connected to a generator. Inside the generator, the turbine spins the magnets, causing the electrons in wires to move, creating an electrical current, which generates electricity.
Combined cycle power stations use two different types of turbines in combination to generate electricity. In addition to burning gas to spin a turbine, they use the waste heat to boil water and produce steam which drives the second turbine to generate more electricity. Combined cycle power stations are generally more efficient and generate approximately 50 per cent more electricity than open cycle power stations because they recycle their fuel to maximise electricity output.
Pumps at gas-fired power stations
Of the many different pumps that can be utilised at a gas-fired power station, there are three main types used: boiler feed pumps, condensate extraction pumps and cooling water pumps. Boilers at power stations are used to generate steam and the boiler feed system is the highest pressure section of the steam cycle. Boiler feed pumps draw water from the deaerator storage tank and feed it to the boiler. They are generally multistage and use mechanical seals.
Condensate extraction pumps draw warm water from the hot-well of a condenser at a pressure between six and 10kPA. Condensate extraction pumps are typically multi-stage pumps fitted with a low net positive suction head (NPSH) first stage impeller. Modern condensate pumps use mechanical seals, however, do still require water injection to prevent air ingress.
Cooling water pumps supply large amounts of water to a condenser to condense the steam into water. There are two general categories of cooling water pumps – open water pumps, which draw water from a lake or the sea before returning it, and cooling tower pumps, which recirculate water through the condenser and pipework system before cooling it in an evaporative cooling tower.
Photograph by Arsineh Houspian.
Gas-fired power station in focus
A new gas-fired power station is set to support electricity reliability in New South Wales, with EnergyAustralia running the first test-fire of its 320MW Tallawarra B gas power station.
The successful test-fire is one of the final major milestones before commercial operation. Located adjacent to EnergyAustralia’s existing combined cycle Tallawarra A station, Tallawarra B will be able to quickly come online when the New South Wales system requires it and when renewables are unavailable, such as on hot days when a large portion of the state is using their air conditioning.
Tallawarra B is a fast-start power station – which means it can start up with just 30 minutes notice – and is set to top up capacity in the New South Wales system. The station can power up to 180,000 homes and small businesses in peak periods.
EnergyAustralia’s Tallawarra B Project Director, Ian Black, said, “As Australia continues to transition away from coal to renewables, fast-start gas generation assets like Tallawarra B will play a critical role in supporting electricity reliability at peak periods and at times of low solar and wind production.”
Tallawarra B integrates a 9F.05 turbine, A78 generator and an exhaust stack with a 54t plume dispersion device to manage and monitor the exhaust plume, all of which were provided and installed by key contractor for the project, GE Vernova.
Tallawarra B will initially come online as a gas-fired power station, however, EnergyAustralia aims to support the development of a hydrogen manufacturing industry in the Illawarra by creating demand at Tallawarra, with both the A and B power stations being ‘hydrogen capable’.
EnergyAustralia has lodged a modification to the planning approval for the power station to use five per cent hydrogen as part of the fuel mix and to install the necessary infrastructure to blend hydrogen with gas.
Though Tallawarra B’s core gas turbine already has the capability to burn a certain amount of hydrogen, GE Vernova has a technology roadmap to increase the power station’s capability to 100 per cent before 2030.
Tallawarra A will be undergoing an upgrade and overhaul in 2024 to increase the capacity and efficiency of the station from 440MW to 480MW while also enabling the use of up to 37 per cent hydrogen as a fuel when green hydrogen is commercially available.
Gas-fired power stations and net zero
The Federal Government has enshrined in law its target to reduce greenhouse gas emissions by 43 per cent from 2005 levels by 2030, and to reach net zero by 2050.
Tallawarra B is just one example of many gas-fired power stations across the nation as Australia moves away from emissions-heavy coal power stations, with gas-fired power stations expected to play an integral role in net zero and the clean energy transition.
