Snowy 2.0 Pumped Storage Power Station

Snowy 2.0 Pumped Storage Power Station or Snowy Hydro 2.0 or simply Snowy 2.0 is a pumped-hydro battery megaproject in New South Wales, Australia. The dispatchable generation project expands upon the original Snowy Mountains Scheme (ex post facto Snowy 1.0) connecting two existing dams through a 27 km underground tunnel and a new, underground pumped-hydro power station. Construction began in 2019. It is expected to supply 2.2 gigawatts of capacity and about 350,000 megawatt hours of large-scale storage to the national electricity market. It is the largest renewable energy project under construction in Australia. It includes one of the largest and deepest cavern excavations ever undertaken. It also includes the longest tunnels at 27 kilometres in length, of any pumped-hydro station ever built.

It is designed for grid stabilization; to be a backup at times of peak demand and for when solar and wind energy are not providing power. It provides invaluable firming capability. Snowy Hydro acts like a giant battery by absorbing, storing, and dispatching energy. Snowy 2.0 can be ‘switched on’ very quickly. The battery is designed to operate for up to 175 hours of temporary supply. It is Australia's largest energy project, estimated to cost 12 billion Australian dollars. By 2023, AU$4.3 billion had been spent. The project is led by public company Snowy Hydro Limited. When complete it is expected to have a large impact on the price and reliability of electric power.

History
Initial plans for a power station at the location were discussed in 1966. Further studies were undertaken in 1980 and 1990. The current project originated as the centrepiece of Malcolm Turnbull's climate change policy in 2017. The original cost of the project was around $2 billion. A feasibility study carried out in 2017 finding the project was both technically and financially feasible. The study was released on 21 December 2017 and found the project cost would be between $3.8 and 4.5 billion.

The first tunnel that was completed by October 2022, was a 2.85 kilometre section that provided main access at Lobs Hole. It was 10 metres in diameter and provides pedestrian and vehicle access into the power station. By May 2023 the emergency, cable and ventilation tunnel was excavated. It is 2.93 kilometre long, 10 metres in diameter and will be used for power station ventilation and high-voltage cables. Excavation of the transformer and machines halls began in June 2023. By February 2024, half of the construction required was complete.

It was originally expected to be completed by 2024. Snowy Hydro 2.0 has been beset by delays and cost blowouts. Delays have been caused by the COVID-19 pandemic, global supply chain disruptions, complex design elements and variable site and geological conditions. The delays have raised concerns that Snowy Hydro will not be ready in time for new solar and wind projects coming online as five coal-fired power stations close. AEMO warns that supply gaps will emerge from 2025. The project is currently expected to be fully operational by the end of 2028 and generating power as early as late 2027.

The project is using three tunnel boring machines to dig tunnels. One of the machines, called Florence was stuck for 19 months after encountering soft rock near Tantangara. Florence launched in March 2022 and was named in honour of Australia’s first female electrical engineer, Florence Violet McKenzie. Eight weeks later the machine was bogged in wet soft ground. The machine is capable of digging 30 to 50 metres a day. In December 2022, a sinkhole opened up above the tunnel. Florence was moving at a pace of six metres a day by early December 2023. In May 2024 the tunnel boring machine was stuck in hard rock. Drilling and blasting is used to dig caverns. The company managing underground blasting operations is Orica. Rock bolts and shotcrete support the exposed solid rock face.

Design and location
It is located remotely within the Kosciuszko National Park in the Snowy Mountains. Snowy Hydro 2.0 will use water from the Talbingo Reservoir (bottom storage) and Tantangara Reservoir (top storage). The dams have a height differential of 700 metres. The new power station is being built by the Italian firm Webuild. It will be located in a cavern 800 metres underground. The underground location allows for reduced environmental impacts within the national park. The operational footprint of the facility is less than 0.01% of the total size of the park.

The Inclined Pressure Shaft (IPS) through which the water will pass is the largest of its kind in the world and facilitates the water’s return to the upper reservoir when the pump-turbines operate in reverse. The IPS is 10 metres in diameter, 1.6 kilometres long and at a 25 degree incline. Pre-cast concrete segments for the shaft are produced at a factory in the town of Cooma. Fatigue resistance is a key design element in the IPS.

The power station will measure 22 metres (m) wide, 50 m high and 250 m long. The station will house six reversible Francis pump-turbine and motor-generator units. Three units will be of variable speed with the remaining of synchronous speed. Each turbine will have a rated output of 333 megawatts. Power generating equipment is being supplied by Voith.

It will be connected to the grid via the HumeLink transmission line. The construction of overhead power lines by TransGrid has been opposed by community advocacy groups. Landholders desire to see the transmission line built underground have been opposed due to prohibitive costs.