Callide coal generator was being operated without approval when it blew up in 2021

The Callide C coal generator in Queensland was being operated without the required regulatory approval when one of its units blew up in May, 2021, and nearly crashed the grid.

The Australian Energy Regulator said on Wednesday that the owner of Callide, the state-owned utility CS Energy, has paid a $67,800 fine for an alleged breach of the National Electricity Law.

The AER says the fine relates to operating a generating system without the required regulatory approval, and it was discovered in its investigations into the events at Callide C, which caused multiple trips of generators and transmission lines on May 25, after what the AER delicately describes as a “plant issue.”

“This alleged breach is distinct from the AER’s ongoing investigation into the events that led to the 25 May 2021 power system event,” the AER said.

“Any entity that owns, controls or operates an electricity generator must apply to the Australian Energy Market Operator (AEMO) to be a Registered Participant for the activity or for an exemption from registration.”

The AER says Callide C was not a Registered Participant, nor did it have an exemption at the time of the explosion, and it turns out that had been the case for a number of years. The AER says an application was only submitted following its investigation, and one was finally obtained last month.

The fine equates to less than one hour’s revenue from the Callide C generator at full capacity (840MW), and based on the average price of wholesale electricity over the past year ($109/MWh), but the AER said it was an important issue.

“Failure to obtain the appropriate registration and exemptions can impede AEMO’s ability to track changes in the control or operation of a generating system,” AER board member Justin Oliver said in a statement.

“This reduced visibility could cause operational issues for AEMO including its ability to contact the appropriate staff that are responsible for the operation of generating systems to raise important matters including compliance issues and activities.”

The AER says it is continuing its investigations into the May 25 incident. AEMO and CS Energy have been approached for comment.

The two Callide C units are now not due to return to service until 2024, with the C4 unit – which suffered the dramatic explosion – delayed until May and July. The C3 unit, which also had to be taken offline to due to problems in the cooling towers, is expected back on line in February, 2024.

Update: In a statement, CS Energy blamed an “historian oversight” on its failure to obtain an exemption as required.