Hundreds of Victorian transmission towers are rusty and at risk of damage

Almost one-in-seven of Victoria’s 13,000 electricity transmission towers are damaged by patchy or extensive rust, with experts warning the state’s ageing network remains increasingly vulnerable to extreme weather.

An assessment done by AusNet Services, which owns and operates Victoria’s transmission network, shows the average transmission tower in Victoria is now about 57 years old. About 8000 of them – more than half – are now about a decade or less from their designed “service life” of 70 years.

Power lines have come down in the You Yangs following windy and stormy weather in Melbourne.Credit: Jason South

The 2020 assessment found 11 extreme wind events had knocked out 45 transmission towers since 1959, with a further six going down in Tuesday’s catastrophic storm. But the pace is accelerating, with more than half of the towers – 25 – coming down in the past 15 years.

“All failed structures were built to historical design standards with inadequate strength to withstand convective downdraft winds occurring during extreme storm events,” says the report, which was published online by the Australian Energy Regulator.

Six towers north of Geelong were flattened on Tuesday by an extreme storm that wrought havoc across the state. The storm left more than half a million homes without power in its wake.

About 44,000 were still without power as of 8.15pm on Thursday. Premier Jacinta Allan, who toured fire-ravaged parts of western Victoria for the second-straight day on Thursday, said it was a significant improvement over 48 hours, although there was still a long way to go.

The government has been at pains to stress that Victoria’s power outages were not caused by the downing of the six towers, an event that prompted the shutdown of the state’s largest power station, AGL’s Loy Yang A.

“It is not an issue of supply that is impacting customers who are without power,” Allan said. “It is an issue of the localised transmission that has not been able to be reconnected because of the massive tree and storm damage that needs to be cleared to enable power workers to go in and reconnect the power safely. This is literally a street-by-street effort. It’s got to be done safely.”

But the loss of the towers has highlighted the looming challenge of upgrading Victoria’s existing transmission network – in addition to the multibillion-dollar cost of adding hundreds of kilometres of new high voltage transmission lines desperately needed to connect future renewable energy projects dotted across the state.

The report, highlighted in an article by energy analyst Dan Lee in the industry publication WattClarity, found that over the six years to 2020, there were also 1512 “suspended failures” on transmission towers. These are less catastrophic than a collapse, including issues that allow the tower to continue to function such as bent or missing structural beams or corroded, exploded or missing bolts.

The report said 86 per cent of Victoria’s 13,000 towers had been assessed as in very good or good condition. But 12 per cent were deemed to be in average condition, with patchy rust, and 1.5 per cent in poor condition, with extensive surface rust.

The report found that 60 towers in Victoria’s north-east near Dederang “present health and safety risks” because they are next to roads. It said they would be replaced before 2022.

However, a spokeswoman for AusNet Services said construction would, in fact, not be completed until January 2025 – at a cost of $34 million. The six towers flattened in Tuesday’s storm were built in 1981. In July 2023, they were inspected and found to be in “good condition”, meaning some rust spots had been found.

The Australian Industry Group’s director of climate change and energy, Tennant Reed, said towers built from the 1960s through to the 1980s were not designed with modern weather conditions – now affected by climate change – in mind.

Reed said any proposals to improve these transmission lines, and pass on their costs through energy bills, would have to justify their value to the Australian Energy Regulator and energy customers.

“Reinforcement or early replacement may well wind up being a good idea, but it will need a lot of scrutiny, and it’ll get it,” he said.

In 2021, a collaboration between the Australian Energy Market Operator, the Bureau of Meteorology and the CSIRO warned of increased risks to transmission from severe winds.

The Electricity Sector Climate Information Project’s final report found there was a link between severe convective winds and historical failures of transmission towers.

Service providers can apply to the Australian Energy Regulator to recoup the cost of natural disaster repairs from their customers through energy bills.

AusNet successfully argued for this after severe weather collapsed six towers in January 2020 on a 500 kilovolt transmission line in southwestern Victoria.

The regulator allowed $2.3 million to be passed on, adding about 40¢ to the typical annual household bill in 2021-22.

State Opposition Leader John Pesutto said the Allan government has had years to better prepare for severe storms.

“In 2024, it’s just not acceptable that people not even that far from Melbourne are still without power and still aren’t able to use their phones,” he said. “We have to do a whole lot better.”

Energy Minister Lily D’Ambrosio said this week a nationally co-ordinated effort was needed between the states and the Commonwealth to improve the resilience of the energy network.

“Everyone is taking this very seriously, and the fact is that Victoria is leading the way in terms of that work on energy network resilience,” she said.

“But it does need a national effort and that is something that certainly I have already signalled to my counterpart energy ministers and Chris Bowen last year about the need for us to ensure that we have more work done.”

Transmission pylons near Geelong that were brought down by strong winds on Tuesday afternoon.Credit: Jason South

Construction of high voltage transmission lines started in Victoria in 1950, with new lines added between the late 1950s and early 1980s.

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