SLOW AND STEADY
The trouble-plagued Snowy Hydro 2.0 scheme is still grinding along at a snail’s pace – but there is light at the end of the tunnel, writes Colin Packham
Some 80m underground in temperatures well in excess of 30C, tunnel boring machine Florence is at the front line of Australia’s energy transition.
Its progress, or lack thereof, has become a metaphor for the country’s attempt to wean its $2.5 trillion economy off its coal dependency.
If Australia is to rapidly reshape its power generation system from its reliance on coal, Snowy Hydro’s massive expansion is desperately needed.
Australia is installing large amounts of solar and wind power, but authorities are increasingly concerned about what will power the country when the sun is not shining or the wind is not blowing.
Snowy Hydro chief executive Dennis Barnes – a year into the role after being lured out of retirement – said the pumped hydro project, by far Australia’s largest, is the only way the country can deliver on its ambitious net-zero plans.
“There is no other technology today. There may be technologies in 15, 20 years, but there is no commercial technology other than pumped hydro,” Mr Barnes said.
Snowy Hydro will use excess renewable energy to pump water uphill. During periods with insufficient renewable generation, water will be released – providing enough electricity to power hundreds of thousands of homes.
But the importance of the Snowy project is matched only by its difficulty.
More than 40km of tunnels must be built, all connecting into a main cavern that will be so deep that it could comfortably hold the Sydney Opera House, which will house an underground power station.
While work is progressing on schedule on much of the works, the same cannot be said of the main 16km tunnel.
Florence – one of three near-2000-tonne boring machines – is at the coalface of what Mr Barnes describes as the “critical path”. Florence became bogged in unexpectedly soft ground in September 2022 and Snowy was forced to rework the tunnel boring machine to allow a so-called “closed mode” where a crew of a dozen could extract the slurry without contamination.
Eventually after a year-long delay, Florence got approval to resume operations in December but progress is still painstakingly slow.
Nearly 500m of the headrace tunnel has now been finished. Florence’s reinforced steel tip moves slowly, creeping forward in 2m increments that can take hours to dig, or claw – which workers say is a more accurate description of the process.
Once Florence’s operator, working from a hi-tech operation room metres behind the extractor point, has guided the machine forward, a crew will then install curved, interlinking concrete segments that line the tunnels. All up, about 130,500 segments will be used to create giant concrete rings across all the tunnels
It is little surprise given the scale of the operation that Florence is moving at a snail’s pace, but Mr Barnes said the developer was working to hasten the process and minimise any further delays.
“We want to be in a position where we push, we build, we push and we build continuously. We are not there yet, but it will come,” said one Snowy worker.
But while the process is being ironed out, Snowy remains behind schedule. The headrace tunnel requires progress of around 13m a day, a feat that the developer is not yet consistently reaching.
And further problems await. In around two years, Snowy will encounter further soft ground, similar to the type that bogged Florence in 2022.
Mr Barnes has flagged the prospect of Snowy purchasing another boring machine that would allow the tunnel to be dug from both directions.
Alternatively, another boring machine, dubbed Kirsten, could be reconfigured to accelerate progress. Mr Barnes said a decision would be made in the next month or two.
But in the meantime, he said the difficulties encountered in the headrace tunnel should not distract from the rapid progress being made across the project.
“Florence not moving was the lightning rod for the project having its difficulties,” he said. “(But) it’s incredible how much has happened, it’s really come on. I think it gives us a bit of cover to quietly get on with a good project.”