ABB technology helps secure Sydney’s water needs

ABB’s high-efficiency motors and variable speed drives have provided an energy efficient solution for transporting large volumes of desalinated water from Sydney’s newest water supply, to over 1.5 million NSW residents.

Clean water is being supplied from the newly commissioned desalination plant, based in Kurnell, south of Sydney, and is capable of producing up to 250 million litres of water a day, which is up to 15 per cent of Sydney’s water needs. The new pump station and pipeline were built by Water Delivery Alliance (WDA) comprising Kellogg Brown and Root, Bovis Lend Lease, McConnell Dowell, Worley Parsons, Environmental Resources Management and Sydney Water, to ensure the city’s water supply against population growth and the damaging effects of climate change and drought caused by reduced rainfall.

Making drinking water flow at the turn of a tap in people’s homes requires millions of litres of desalinated water to be pumped via an 18 km pipeline to Erskineville, in Sydney’s inner-west, from storage tanks at the plant. Critical parts of the process are facilitated by two ABB drive systems installed at the desalination plants’ pumping station.

"A significant factor in selecting ABB as the supplier for this project was the compatibility between the ABB supplied variable speed drives (vsd) and the ABB, Nijhuis supplied motors. This compatibility aligned closely with one of the key overall project objectives of sustainability.The high efficiency pump-motor-vsd set allowed The Alliance to minimise life-cycle costs. ABB’s ability to guarantee an equipment efficiency rating of more than 96 percent played a major role in this decision as it directly translates into affordable potable water,” said Tallaesen the Project Manager for the pump station.

Adrian Heaton, ABB’s NSW regional sales manager for drives and motors explains why evaluating operating costs is critical for water applications: “Electrical power consumption is one of the largest running costs of a desalination plant that uses reverse osmosis technology. Therefore it was important for WDA to ensure that all the necessary factory and efficiency string tests were carried out in conformance with the contract requirements.

“The string testing involved running the pump, motor, variable speed drives with integral transformers in sequence at actual load conditions to prove minimum life-cycle costs. We are pleased to report that the water pump discharge system which is capable of discharging water at 3,183 litres per second satisfied the test requirements in every respect. String testing was performed at Nijhuis, the pump manufacturer’s plant in Holland,” said Heaton.

According to Heaton, the water consortium’s investment in ABB’s technology will have a huge impact on reducing their daily operating costs because water consumption can vary greatly during any given day. Consequently, the flow and pressure of Nijhuis pumps need to be controlled and adjusted either electrically with variable speed drives, or mechanically with fixed-speed solutions, such as inlet guide vanes, throttling valves or hydraulic couplings.

By selecting a variable speed drives solution, changing the flow is achieved simply by changing the motor speed, which can be compared to reducing the speed by taking the foot off the accelerator and switching to a lower gear. The pumps can then operate at the best efficiency point under all operating conditions.

Since pumps typically run at partial load, huge energy savings are achieved by controlling their speed with variable speed drives. The power required to run a pump is roughly proportional to the cube of the speed, i.e. a small reduction in speed can make a big reduction in the energy consumption. A pump running at half speed consumes as little as one eighth of the energy compared to one running at full speed.

WDA’s investment in two 1.35 MW, 3.3 kV high-efficiency motors from ABB’s AMA-family of modular induction machines, in combination with drives, is even more effective. The energy savings quickly add up because the energy used to run a motor over its lifetime costs 100 times more than the motor itself.

ABB designed the motors to operate at 66 Hz as this produces the highest efficiency, at minimum current, at most economical execution to suit the drives.

The ACS 1000i model is a fully integrated standard drive which includes input transformer and input contactor. The combination is an unbeatable solution for pumping stations in the water industry, and by employing the drives on pumps instead of throttling, the energy bill can be reduced by as much as 60 percent.

Sydney Water reinforced their commitment to sustainability by opting for a renewable energy power supply to run the desalination plant and the pump station. The plant which uses reverse osmosis technology to extract fresh water from the seawater, is completely powered by renewable energy sourced from the Capital Wind Farm in Canberra. ABB also played an important role in the supply side of the renewable energy equation – having been the principle construction contractor for the wind farm.