What happened

An explosion and major fire struck Unit 4 (C4) at the CS Energy-operated Callide C power station near Biloela in central Queensland just before 2:00pm on 25 May 2021. A union representative described the event as a catastrophic failure involving the unit's hydrogen-cooled generator or main turbine. The failure triggered the network's automatic protective disconnection of other generating units to protect the wider system, cascading into outages that left more than 470,000 Queensland customers without power, disrupting shopping centres, sewage treatment plants, traffic lights, businesses and households across the state; the Australian Energy Market Operator asked residents to reduce energy use as supply was restored. No injuries were reported. CS Energy chief executive Andrew Bills acknowledged significant damage to Unit 4 and said the company would investigate both the fire's cause and the performance of alarm and control systems; the Australian Energy Regulator and AEMO also opened investigations. Subsequent years-long regulatory and legal proceedings followed: a 2024 technical report found CS Energy had failed to implement effective safety practices, the Australian Energy Regulator brought legal action against Callide Power Trading over the explosion, and in January 2024 the Federal Court ordered a fresh investigation after procedural issues with an earlier investigator. Those later findings and proceedings are noted for context but are not treated here as a final, unappealable determination of cause or liability, since litigation continued after the reports were published. This was reported and treated throughout as an accidental equipment failure, not an attack.

When cited sources give different casualty, damage or spill figures for this event, they’re reported side by side above rather than merged into one number. See how confidence levels work.