The troubled Callide C coal plant has suffered another major incident – described as an “explosion” or a “blast” – that will take one 420 megawatt (MW) unit offline for at least two months, just as the new state LNP government announces a potentially costly life extension to its neighbouring facilities.
The Callide C4 unit was offline for more than three years after an explosion ripped through it in 2021, nearly causing a state-wide blackout, and problems were discovered in the cooling towers at C3, which were offline for more than a year.
The state-owned CS Energy, which operates the plants on behalf of a joint venture, says the new incident occurred last Friday at C3, when a significant clinker (an aggregation of hardened ash) detached from an internal boiler wall, causing a pressure spike within the furnace.
CS Energy says clinker formation is common in coal-fired power stations, and they normally fall to the bottom of the boiler for easy removal. However, the events on Friday will require significant repairs due to damage to the cladding in the upper section of the boil.
The unit will not be back on line until the end of May.
“No one was in the area at the time of the event and there were no injuries,” the company said in a statement. “The unit’s protection systems worked as design to shut down the unit.” (The graph above shows the abrupt shut down of the unit on Friday).
“Investigations and inspections are ongoing to fully assess what occurred and the repairs required to safely return the unit to service,” the company said. “Access is restricted to key personnel only.”
Access was only allowed for the first time after the incident on Wednesday and further restrictions on movements have been imposed across the company’s coal fired power stations as a precaution.
“Across all CS Energy power stations, we have strengthened clinker controls and are continuing proactive clinker deloads as guided by management tools. Access is also being restricted in boiler areas while clinker deloads are carried out.”
The revelation comes just days after the state LNP government announced an extension to the life of the neighbouring Callide B coal units, which were due to close in 2028 but which will now be kept open for another two or three years.
Callide B is wholly owned by CS Energy and has 700 MW of capacity.
Analysts say the life extension could cost more than $400 million a year, and the market operator has pointed out that the unreliability of ageing coal units remains the biggest threat to grid reliability.
However, the new state LNP government has made clear its intention to scrap the state’s legislated renewable energy targets, which set an initial goal of 50 per cent by 2030 and through to 80 per cent by 2035. Queensland remains the country’s most coal dependent state with a coal share of 65 per cent of local demand.
The Labor opposition energy spokesman Lance McCallum said on Thursday it was a “miracle” that no one was injured in the incident, attacked the government for keeping it a secret even as it unveiled its coal extension plan.
“The fact that the energy minister chose to keep that a secret and not be open and transparent with Queenslanders and with the national electricity market, and then stood up nearly days later, to make a major policy announcement to the energy industry … reeks of an absolute cover up,” McCallum said.
“What we’re seeing in Queensland is a government that doesn’t really have a coherent energy policy and at best, have announced a plan to get a plan together, but we just found out that they’ve covered up an explosion. It’s terrible.”
The Queensland Conservation Council, which says extending the life of Callide B could cost more than $400 million a year, also highlighted the increasing unreliability of the Callide coal hub.
“The Crisafulli Government is throwing hundreds of millions of dollars at coal-fired power stations and they’re still breaking down because our coal fleet is ageing and increasingly unreliable. No amount of maintenance is going to change that,” QCC energy expert Clare Silcock said.
“The Callide power stations have been plagued by incidents, most notably the explosion of unit C4 and the cooling tower collapse at unit C3. Over the last 18 months, the Callide power stations have only been available, on average, at 50% of their capacity.
“At Callide B, unit B1 suffered two outages during January 2025, one of the hottest months of the year, despite a major maintenance project taking it offline from July to December 2024.
“To keep the lights on it’s clear we need to diversify our energy supply and build more renewable energy backed by storage. Extending the life of coal just means waiting around for the next breakdown.”
Federal energy and climate minister Chris Bowen on Wednesday said he had not had time to assess the impact of the LNP’s coal extension decision, but made clear that ageing coal plants were the weak link in the national grid.
“Coal fired power is the most unreliable form of energy in our grid, as well as being high, very high emissions, of course, with not, not a day in the last two years where we haven’t seen a breakdown in energy in a coal fire power station,” he told journalists on the sidelines of the Smart Energy Council conference in Sydney.
“That is why we are proceeding with the massive rollout of renewable energy and dispatchable energy supported by storage to ensure that states can make the decisions that they want to make, to move, when appropriate, away from the coal fired power stations and close them as part of an orderly managed transition.”
Stephanie Bashir CEO of Nexa Advisory said Australia’s coal-fired power stations are old and most have reached the end of life. “Our research shows clearly how unreliable, expensive and dirty they all are. The extensions of these powerplants are costing Australians,” he said.
“This blast at Callide is the third major incident at this power station. It is yet another example of why it is imperative we shut them down on time. We can’t rely on them, they don’t even make good a good band- aids. And in this instance it seems we were very lucky someone wasn’t seriously hurt.”
