The electricity operator at the centre of Queensland’s worst power outage in decades has launched an investigation into the “catastrophic failure” after more than 470,000 customers lost power following an explosion at Callide Power Station.

The plant at Biloela in central Queensland lost power just before 2pm on Tuesday triggering outages across the state that blacked out shopping centres, sewage treatment plants, traffic lights, businesses and households.

Energy minister Mick de Brenni said the power was restored with help from other states and renewables.

“We had our power stations operating last night, we had our wind farms operating last night, we had Wivenhoe pumped hydro operating last night and those facilities will continue to operate for electricity and keep the lights on while we restore power out at Callide,” he said on Wednesday.

“I’m thankful no-one was injured in this incident and we’re working hard to resolve these unprecedented issues as quickly as we can,” he said.

“Essential services such as hospitals, transport networks, ports, airports and other key infrastructure will stay online.”

Supply was restored to many customers within a few hours on Tuesday, but the Australian Energy Market Operator (AEMO) on Tuesday night asked Queenslanders to reduce their energy usage.

CS Energy Chief Executive Officer Andrew Bills said the investigation would need to determine the root cause of the fire.

“Obviously the turbine four you can see the damage that’s occurred there is significant, we’ll begin to understand more about that during the course of the day,” he said.

“There was both sighting of the fire and our control systems so we’ll obviously investigate those alarms and systems during the course of the day to understand what led to it.

“When you have an event like this you’ve got to understand root course, what led to it and make sure there’s no risk of that happening anywhere else.”

Traffic lights were out across Brisbane on Tuesday after the blackout. Photo: ABC

The station was evacuated and a 550-metre exclusion zone put in place as fire crews worked to extinguish the blaze.

Mr de Brenni wasn’t able to say when the turbines would be operational.

“There’s some debris and some smoke damage in the plant at the moment,” he said.

Queensland Premier Annastacia Palaszczuk told parliament the investigation into what caused the explosion would begin as soon as it was safe.

“Yesterday we confronted something that has never happened before: an explosion and major fire in a power-station,” she said on Wednesday.

“I’m advised damage is limited and we expect it to return to full service.”

CS Energy’s power stations at Callide, Kogan and Gladstone deliver about 30 per cent of the state’s electricity.

Fault triggered a cascading blackout

The outage at the Callide station had a domino effect, tripping other plants in the network.

A spokesman for Energex, Danny Donald, said the network could sense when there was not enough supply to meet demand.

“It will start switching off – just as your house would if it senses your toaster is the fault – it’ll switch your whole house off to protect your house from any further damage,” Mr Donald said.

“That’s exactly what happened here but on a much grander scale, of course.”

He said he had not seen such a bad blackout in his 15 years in the industry.

“It’s been decades since we’ve had anything of that magnitude,” he said.

Shoppers were briefly trapped inside when power was lost at Forest Lake shopping centre. Photo: ABC News/ Melanie Vujkovic

Failure being probed by regulators

The wholesale electricity price in Queensland and New South Wales spiked after the failure.

The Australian Energy Regulator (AER) said it monitors and reports on the causes when wholesale spot prices exceed $5000 per megawatt hour (MWh).

“As high price events occurred in Queensland and New South Wales following the Callide C Power Station event, the AER will prepare and publish a report within 40 business days.”

The Australian Energy Market Operator (AEMO) is also investigating.

‘Worst-case scenario,’ according to union

Shane Brunker, the district vice-president of the CFMMEU, said it appeared the hydrogen-filled generator or the main turbine had a “catastrophic failure”.

“The scenario of a hydrogen-filled generator exploding or failing mechanically causing hydrogen leaks and then also oil leaks, is probably the worst-case scenario in a coal-fired power station,” he said.

“All the safety protocols were enacted straight away and it was a very speedy and efficient evacuation.

“My biggest concern is for the 350 direct and indirect employees of that station on their futures now.”

Mr de Brenni said a meeting with the workforce would happen later on Wednesday morning.

-ABC