Pumped Storage Hydro

To speed up timeline, Snowy 2.0 pumped storage gets fourth tunnel boring machine

Snowy Hydro said that new ground testing techniques have provided a better understanding of the full extent of a complex fault zone on the route of the 17 kilometer tunnel that will connect Snowy 2.0’s upper reservoir to its underground power station.
To speed up timeline, Snowy 2.0 pumped storage gets fourth tunnel boring machine

A new tunnel boring machine (TBM) will be deployed to help keep the 2.2 GW Snowy 2.0 pumped storage project on its delivery timeline, subject to approval by the New South Wales Department of Planning, Housing and Infrastructure.

Snowy Hydro said that new ground testing techniques have provided a better understanding of the full extent of a complex fault zone on the route of the 17-km-long tunnel that will connect Snowy 2.0’s upper reservoir to its underground power station.

Snowy Hydro CEO Dennis Barnes said activating a fourth TBM is the right course of action, given that what is now known about the tunneling challenges ahead has provided the opportunity to mature the design.

“We’ve always known the fault zone was there and I’ve said in the past we will need to take action,” Barnes said. ”While the fault zone is not a surprise, further ground testing since the project reset has revealed it is far more geologically challenging than earlier investigations indicated. We’ve carefully considered a range of options to get through the fault zone and overcome the initial design immaturity. Bringing in a fourth machine is the best way to keep the Snowy 2.0 on track for its target completion date of December 2028.”

A modification for Snowy 2.0’s project approval has been submitted to the NSW Department of Planning, Housing and Infrastructure and will be subject to the department’s independent community consultation and assessment processes. The planning modification seeks approval for a change to construction methods within the project’s already approved work zone. There is no proposal to increase approved land clearing areas, surface or groundwater impacts.

“We’re mindful that we are building Snowy 2.0 in a precious and protected national park. We have worked diligently to arrive at a proposal that does not step outside our existing construction area or increase our already approved impacts,” Barnes said.

While the need for a new TBM is driven by new information about the fault zone, Barnes said the “disappointing” performance of Florence, the TBM excavating the same tunnel that the new machine will also work on, has contributed to the need to take action.

“It’s difficult to say with certainty whether the same action would be needed if Florence had performed as we had hoped. However, it’s likely that the fourth machine would still be needed,” Barnes said.

According to AEMO (the Australian Energy Market Operator), Snowy 2.0 will supply a majority of the National Electricity Market’s storage needs, greater than every other storage asset combined.

“Snowy 2.0 is critical to Australia’s energy future. We need to get this job done,” Barnes said.

Subject to planning approval, the new machine will be tunneling before the end of 2025.

In May, progress by TBM Florence in the headrace tunnel for the Snowy 2.0 project slowed in very hard and abrasive rock, and the project ceased excavation by the TBM on May 16 due to rock pinching on the machine’s shield.

That wasn’t the first time the TBMs working on the project have been stopped. In December 2023, Hydro Review reported that tunnel work on the headrace adit at Tantangara for the Snowy 2.0 pumped storage project was restarted after the NSW government approval for the project’s planning modification.

And in May 2023, the timeline and budget were reset for the project, with Snowy Hydro saying that one category of factors contributing to the schedule delays and likely cost increases was the impact of variable site and geological conditions, with the most impactful being the soft ground encountered that is delaying TBM Florence’s progress at Tantangara.

The Snowy 2.0 pumped storage project is the largest renewable energy project under construction in Australia and will provide crucial deep storage central to the country’s renewable transition, according to a release. The value of Snowy 2.0 to the national electricity market has increased materially since the final investment decision in December 2018. Snowy Hydro said it would deliver an additional 200 MW or 10% capacity, bringing total capacity to 2,200 MW. Snowy 2.0 will provide 350,000 MWh of energy storage for 150 years.