Callide Unit C4 recovery

This page contains information and updates about the Callide Unit C4 incident, investigations into its cause and works to return the unit to service.

BACKGROUND

Callide Power Station is comprised of two power plants, Callide B and C, each with two generating units (B1 and B2, C3 and C4). CS Energy owns 100 per cent of Callide B and owns Callide C in a 50/50 joint venture (JV) with IG Power.

On 25 May 2021 an incident occurred on Unit C4, which resulted in an explosion and substantial damage to the unit, forcing it offline. Shortly afterwards Callide’s other operating units tripped and went offline. Multiple power stations and high voltage transmission lines in Central Queensland also tripped, leading to a significant reduction of load and temporary separation between Queensland and the rest of the NEM.

Our first priority was to make sure workers and the Callide site were safe. The power station was fully evacuated and nobody was injured.

CS ENERGY TECHNICAL INVESTIGATION AND SAFETY IMPROVEMENTS

CS Energy is committed to understanding the facts that led to the incident so we can learn from it and improve the safety of our people and plant.

On 13 February 2024 we released a report on the technical contributing factors to the Callide Unit C4 incident and the actions we have taken to prevent a similar event from happening again.

Download our report: Callide Unit C4 turbine generator failure - Technical investigation summary (PDF 1.3MB)

We have introduced a range of safety improvements and have shared our initial learnings with other power station operators.

Our internal analysis, as well as a report by the Australian Energy Marker Operator, identified that Unit C4’s generator protection systems did not operate on the day of the C4 event, most likely because of a loss of DC power supplies to the unit.

We have carried out work to enhance Callide C’s generator protection systems and DC power supplies, and improvements have been made to DC supplies at Kogan Creek Power Station, following a review of its DC supplies and protection systems.

We have also updated electrical access procedures, and our operational risk assessment processes that apply to all of our sites.

CS Energy will make further improvements and will share any additional learnings with industry.

INDEPENDENT INVESTIGATION

Dr Sean Brady is leading an external, independent investigation and review of the incident.

His investigation will make findings from an independent perspective on why the C4 incident happened, including both the technical and organisational factors that could have contributed to the event.

The investigation has included independent testing, and involved the collection and analysis of a considerable volume of evidence.

UNIT C4 RECOVERY

CS Energy is working with our Callide C JV partner IG Power on returning Unit C4 to service.

The bulk of the rebuild of Unit C4 has been completed. The project team is working through a commissioning plan to align with the rebuild of the unit’s cooling tower, as there are some final works that cannot be done until the unit is ready to be commissioned

The unit is forecast to make a staged return to service starting on 30 June 2024.

Returning Unit C4 to service is a unique and complex project. The return to service date is based on the information that the JV has available at this point in time and may be subject to further change.