The Victorian government has declared an “energy emergency” to allow EnergyAustralia to urgently divert the Morwell River away from the Yallourn coal mine so it can repair a protective wall that is at risk of collapsing.
EnergyAustralia revealed on Wednesday that high water levels resulting from last week’s extreme weather in Victoria had left visible cracks in the Morwell River diversion wall. As a result it stopped production in much of the mine, and limited generation at the neighbouring Yallourn power plant to just one of its four units in order to conserve coal.
Victorian Environment and Energy Minister Lily D’Ambrosio said on Thursday morning the diversion wall could “breach at any moment with very little notice”, meaning there was no time to get the usual approvals for such radical an intervention as diverting a river.
“This morning … we have declared an energy emergency under the Electricity Act of Victoria,” D’Ambrosio said.
“What that means … is that the normal regulatory approvals that are with us right now will be judiciously, cautiously, carefully, but with the due urgency that the situation requires, to be bypassed … to enable EnergyAustralia to get in there and be able to undertake those emergency repairs.”
Energy Australia said on Thursday afternoon it would submit a proposal to the Victorian Government on Friday that would “outline in detail the options available to mitigate the current situation”.
“The weather has been kind to us in the past two days and this has meant that the water in the river diversion has subsided, allowing us to understand better the impact,” said energy executive Liz Wetcott.
“Movement in the ground around the river diversion has stabilised but there is cracking, and we still need to work on actions to stop the water flow around the areas of concern.
“Temporary measures to seal the cracks are already occurring and a technician has arrived from interstate to install a high-tech ground radar that can help us identify movement in the mine. Geotechnical experts are also on site looking at solutions.”
The Morwell River runs straight through the Yallourn brown coal mine. The diversion wall is designed to protect the mine from flooding – an event that could force the neighbouring power plant to shut down. Coal from the mine is usually extracted 24 hours a day, seven days a week to feed the nearby 1.48GW Yallourn power plant.
EnergyAustralia shut down three units at Yallourn late Friday and early Saturday and, after restarting one unit on Tuesday, said on Wednesday it had shut down operations in much of the mine and was running the power plant at reduced levels to preserve dwindling coal supply.
It said it was considering a number of measures, including an attempt to divert the Morwell River to protect the mine. Thursday’s announcement confirms this will now go ahead.
EnergyAustralia said on Wednesday the Australian Energy Market Operator had told it that despite the reduced capacity at Yallourn, overall power supply was “sufficient to meet demand in all National Electricity Network regions, including Victoria.” It did not say what would happen if production in the mine ceased indefinitely.
“We have suspended access to impacted areas, an exclusion zone has been established and independent geotechnical experts, together with our onsite team and government, are working on actions to stop the water flow around the area of concern,” the company said.
“Today, we are preparing for limited mining activity in another part of our mine that is 4km from the area of concern. This will be conducted in line with detailed risk assessments, consultation with the Victorian mining regulator and in strict accordance with our health and safety plans,” the company said.
Environment Victoria warned the situation resembled events in 2012, when heavy rain caused the diversion wall to collapse and the mine was flooded with 60 billion litres of water. It took nearly two years to repair the wall, at a cost of $150 million.
The flood initially forced the mine to stop production, while three of the four generating units were shut off, with the fourth running at reduced capacity. The station’s main coal conveyor belt was also temporarily out of action, forcing TruEnergy, as EnergyAustralia was then known, to deliver the coal by truck.
Along with the risk to energy supply, environmental groups are also concerned that if the mine floods, ash pits at the bottom of the mine could contaminate the river – as happened last time.
There are also concerns that the river may be diverted into the disused Hazelwood pit, which also contains toxic coal ash, and this could contaminate groundwater.
Environment Victoria said it supported the Victorian government’s decision to declare an energy emergency, but highlighted the risk of contaminating groundwater. Dr Nicholas Aberle, a campaigns manager with the NGO, said it was not yet clear how the river would be diverted.
“In practice this could mean anything from diverting the water into an inactive part of the Yallourn mine to the west, diverting the Morwell River upstream so it tips into the empty Hazelwood mine pit, or even piping it around the mine into the Latrobe River,” he said.
“We don’t yet know what options are on the table. But whatever they are, EnergyAustralia and the government also need to consider the risk of groundwater contamination when diverting the river water.
“The Hazelwood pit, for example, has toxic coal ash that we know has been polluting groundwater for the last 15 years. Covering this coal ash with water could exacerbate that situation.”
Aberle also stressed that this showed the risk of relying so heavily on big baseload coal plants to provide so much of the state’s electricity.
“It shows we need to transition to a grid with more renewable energy and storage spread across the state, ensuring geographically diverse sources of energy.”
He added, though, that Victoria had made “great strides” in this area, meaning the effect of taking Yallourn offline would not be as dire today as it would have been just a few years ago – a point also made by D’Ambrosio during her press conference.
In 2020, 26 per cent of Victoria’s electricity came from renewable sources, up from 12 per cent in 2014. Solar contributed the biggest portion, followed by hydropower, then wind. The 2020 figure meant Victoria met its official 2020 renewable energy target of 25 per cent of electricity generation. It has now committed ramp that up to 50 per cent by 2030.
Despite the swift rollout of renewables, brown coal – the most climate polluting of all the fossil fuels – is still by far Victoria’s biggest source of power, generating 69 per cent of the state’s electricity in the 2019-20 financial year. Yallourn generates around 20 per cent of Victoria’s electricity.
This will change significantly in 2028, when Energy Australia says it will close Yallourn power station. That will leave AGL’s Loy Yang A and Alinta Energy’s Loy Yang B as Victoria’s last remaining coal plants. Together they supply around 50 per cent of Victoria’s electricity.
James Fernyhough is a reporter at RenewEconomy. He has worked at The Australian Financial Review and the Financial Times, and is interested in all things related to climate change and the transition to a low-carbon economy.