There is a consensus among key players that last night’s South Australia-wide power failure was caused when a massive storm knocked out 23 transmission towers servicing Adelaide’s north.

Key energy bodies and energy market experts say the entire state lost power because the equivalent of a system-wide short-circuit switch was triggered by the damaged power lines.

They say the automatic cut-off protected South Australians from injury and protected the electricity grid across eastern Australia from damage.

But the organisation that operates the power grid — the Australian Energy Market Operator — says that while the root cause of the blackout was the loss of power lines north of Adelaide, questions remained about why the rest of the state was powered down.

Prime Minister Malcolm Turnbull has suggested South Australia’s reliance on renewable energy sources had contributed to a lack of energy security in the state. But every industry body involved in the market says the state’s energy mix was irrelevant to the blackout.

What about the time taken to reboot the system?

SA Opposition Leader Steven Marshall has suggested that the reboot of the power network has been slow, but an energy market expert has told InDaily restarting the state’s electricity system from “black” has been an extraordinary success.

So while there is general consensus in industry circles about the root cause of the blackout, questions remain about the breadth of the problem and the rebooting process.

What caused the blackout?

Electranet Network Services executive manager Simon Emms said the state-wide blackout was triggered by an automatic shut-down when power lines fell to the ground.

“In the afternoon, there was a severe weather event that happened in the mid-north and that resulted in approximately 700 megawatts of generation tripping off,” he told ABC 891. “Once the system volts get out of the technical parameters then the system shuts down. It’s sort of like a car stalling because it loses power and it will just stall. It all happened in probably five to seven seconds.

“Within the first five seconds there were three events, so we suspect that that is the lines coming to the ground and then, the next couple of seconds, it was the system trying to operate within the technical parameters — it couldn’t, so it turned it off.”

SA Power Networks spokesperson Paul Roberts agreed, telling FIVEaa radio that vital poles and wires were damaged in the storm, cutting off energy supply.

“The transmission infrastructure in this case was battered and it meant that we weren’t getting any supply, but it also meant that this protection system, which is built into the national electricity network and into South Australia’s electricity network … responded to protect your safety and mine.”

According to the Australian Energy Market Operator (AEMO), the root cause of the blackout event was the loss of power lines during the storm that supply power north of Adelaide.

However, the reason for the failure of electricity supply across the rest of the state was still being investigated.

“Initial investigations have identified the root cause of the event is likely to be the multiple loss of 275 kilovolt (kV) power lines during severe storm activity in the state,” a statement on the AEMO’s website says.

“These transmission lines form part of the backbone of South Australia’s power system and support supply and generation north of Adelaide. The reason why a cascading failure of the remainder of the South Australia network occurred is still to be identified and is subject to further investigation.”

That’s a question that will be the heart of the political fallout: Opposition Leader Steven Marshall insists that storm damage in one part of the state shouldn’t knock out the entire system.

Independent Snator Nick Xenophon wants an inquiry to examine this question, among others.

Energy system expert Dylan McConnell, from the Melbourne Energy Institute at the University of Melbourne, agrees with the key bodies’ assessment of the root cause, adding the failure had nothing to do with South Australia’s mix of electricity generation.

“The transmission failure is completely independent of the generation that underpins it,” he told InDaily.

He said questions could be explored about the quality of the infrastructure that was damaged, but that raised the issue of gold plating: how much is the community prepared to spend to safeguard the system against rare events?

Were renewables to blame?

Responding to the blackout, Prime Minister Malcolm Turnbull said that South Australia had relied on “intermittent renewables” that had placed different strains and pressures on the electricity grid than traditional, base load power from fossil fuels or hydro.

He said that several state Labor governments — not just in South Australia — had set “extremely aggressive, extremely unrealistic” targets for renewable energy use.

“Targeting lower emissions is very important but it must be consistent with energy security.”

Federal Energy Minister Josh Frydenberg said that while last night’s blackout was not linked with South Australia’s reliance on renewable energy, there were questions to be asked about the wisdom the state’s rapid uptake of green power.

“There are two issues: what happened last night — a once in a 50 year weather event — and there are questions about how resilient the system is and how we can prevent and protect against that.

“Then there’s the question about the huge uptake of renewables: [including] what that does to the overall system both in terms of price as well as reliability.”

But did renewable electricity sources contribute to the blackout?

According to Emms, South Australia’s energy generation mix was irrelevant.

“The cause of it is unrelated to the type of generation we lost and we do have,” he told ABC 891 this morning.

Clean Energy Council policy manager Tom Butler told InDaily there was no evidence that South Australia’s reliance on renewable electricity was a factor in the blackout.

He said that all power generation types — even if coal-fired electricity were still being produced in South Australia — would have shut down automatically during a weather event such the one experienced last night.

Australian Conservation Council campaigns director Paul Sinclair concurred.

“If South Australia was powered entirely by coal, rather than by 40% clean renewable energy, as it is, this blackout would still have happened,” he said.

“In fact, at the time of the outage, wind power was pumping out 1000 megawatts — it was working.”

Energy market expert Dylan McConnell agreed — renewables weren’t connected to the failure.

His colleague Roger Dargaville, the deputy director of the Energy Research Institute, wrote on The Conversation website that: “… as we find out more about the incident it may become apparent that there are weaknesses in the grid that need addressing. However it is hard to imagine how the high penetration of renewable energy in the state could be implicated in this incident.”

Did SA’s mix of generation lead to a delay in re-booting the system?

A report on South Australia’s electricity system, published by AEMO last month, warned that there was a limited capacity to reboot the state’s electricity system in the event of a total blackout.

“There is a limited pool of strategically-located SRAS (system restart ancillary services) in South Australia to meet the current standard,” the report says.

“This indicates reliance on a single fuel source for all generation involved in the system restoration process in South Australia.

“Many of these gas-powered generating units do not have dedicated fuel storage facilities, exposing South Australia to further risk if there was a gas supply interruption during system restoration.”

However McConnell, who has expertise in the cost structure of energy technologies and the electricity market, said the complete re-boot overnight had been an “incredible feat”.

He said to re-start almost the entire state’s electricity supply “from black” within hours was unprecedented in the national electricity market.

“The proof of the pudding is in the eating  – and this is quite a success story, to be honest,” he told InDaily.

“As far as I’m aware, they (AEMO) have never put these black start procedures into action before (at this scale).”

Normally, parts of a system would be shut down across suburbs or a region.

“But to restart an entire region I don’t think has been done in SA before and I don’t think it’s been done in the national electricity market before. It’s quite an incredible feat, really.”

–with AAP.

*This article was originally published at InDaily