The Callide C Power Station joint venture has announced further delays in the return to service of Unit C4, out of action since an explosion in May 2021 that left almost half a million people without power.

Cooling towers at the plant, outside Biloela, have also undergone a rebuild following the structural failure of a section of the Unit C3 cooling tower in late 2022.

CS Energy chief executive officer Darren Busine said the change in date from July 22 to August 31 for C4’s return was necessary to provide additional time for testing and quality assurance. 

Related: State accused of ‘mother of all cover-ups’ in Callide row

“This is the first time in Queensland a major generating unit and its cooling tower have been completely rebuilt and integrated with existing infrastructure,” Mr Busine said.

“It is also nearly 20 years since a new coal-fired generator and cooling tower was put into service in Queensland, which was at Kogan Creek Power Station.

“For many of our people at Callide, this is the first time they have been involved in the commissioning of a new coal-fired generator and they have my full support in taking all the necessary precautions to ensure that C4 is returned to service in a safe and methodical manner.

“While this is a complex and challenging project, we are making good progress. The final electrical rectification works on C4 have been completed and construction of the new C4 cooling tower is progressing to schedule.

Related: Callide repair effort staggers towards finish line

“The cooling tower basin has been filled, and cooling water is circulating in preparation for providing the required cooling to support commissioning of C4.

“We are being extra diligent in returning C4 to service – the safety of our people and plant is our priority.”

The power station is at the centre of a political storm over the generating unit’s failure.

Opposition leader David Crisafulli has slammed the circumstances surrounding the 2021 explosion at the plant as one of the greatest scandals seen in Queensland for a long time and accused the Labor Government of ‘the mother of all cover-ups’.

Callide Power Station is comprised of two power plants, Callide B and C, each with two generating units (B1 and B2, C3 and C4). Units B1, B2 and C3 are all generating electricity. 

Image at top of page: The damaged C4 generating unit immediately after the 2021 explosion.