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Regular readers of this column with a critical interest in the renewables transition – differentiated from those who are blinkered true believers – will know that the intermittent nature of wind and solar energy is the Achilles heel of the Albanese Government’s strategy.

The real zealots, who shun natural gas power generation as a potential solution to this fatal flaw in the reliable supply of electricity, fall back on batteries as the salvation of their renewables-only dream.

But, apart from their prohibitive cost and short discharge capabilities, dependence on batteries becomes highly risky when the wind doesn’t blow and the sun doesn’t shine enough to charge them.

Relying on the two major sources of renewable energy to sustain a plethora of big batteries ostensibly backing up statewide electricity networks during wind and sun droughts is fraught with danger.

Apart from the obvious solar absence between sunset and sunrise, there are an alarming number of very cloudy and low wind days each year when wind farms and solar panels are pretty useless.

Those periods, known in the renewables world by the German word “dunkelflaute”, were disregarded by the zealots and most energy planners until very recently.

This week the national grid operator, AEMO, released a new draft Integrated System Plan (ISP) for the east coast’s national energy market (NEM) which finally appears to take into account fully these “lulls” in wind and solar power.

The fact it has taken them so long is alarming. AEMO’s new draft plan insists a big increase in gas generation capacity and pumped hydro could fill the shortfalls.

But here in WA, the Cook Labor Government is having a different kind of dunkelflaute with its own renewables plan, the centrepiece of which remains the promise to close State-run coal-fired power plants by the end of 2029.

Labor released the inaugural Whole of System Plan (WOSP) in 2020, which risibly showed coal continuing past 2040. Premier Mark McGowan shredded that basic projection two years later when he announced Collie’s demise.

Since then, updates to the WOSP have been promised, but never delivered. One due this year has been shoved off to 2027, with no adequate explanation, but creating plenty of suspicions that Labor’s strategy is in tatters.

No wonder the rollout of renewables projects in WA is so far behind – other than those funding big batteries which opportunistically plunder the AEMO bid system during peak periods for lucrative profits, pushing up power prices.

At least there is an element of transparency in the Federal plan through AEMO’s ISP, even though its conclusions are damned by one simple caveat.

“The Draft 2026 ISP reaffirms that renewable energy, connected by transmission and distribution, firmed with storage and backed up by gas, presents the least-cost way to supply secure and reliable electricity to consumers through to 2050, as coal plants retire and while meeting government policies,” AEMO says.

Unfortunately, “while meeting government policies” means it is a political strategy based on reducing carbon emissions at lowest cost, not one primarily delivering cheap and reliable power. This is where the next federal election will be fought, if the Opposition ever wakes up.

AEMO’s new plan importantly extends the use of coal on the east coast by 12 years to 2049. That questions Labor’s ability to supply reliable electricity in WA from 2029 without coal.

The ISP stresses a high reliance on the expanded use of gas to meet renewable power shortfalls, which also demands an urgent response from the Cook Government about the ability of the near-capacity Dampier-Perth pipeline to deliver adequate future supplies.

Since 2022, this column has been airing the research of engineer Mark Chatfield, a former head of generation for WA’s State-owned electricity utility who later ran Queensland’s biggest power company, CS Energy.

Chatfield’s modelling sounded the alarm on the vulnerabilities of our South-West network after coal generation is axed, particularly the unseen risk of dunkelflautes.

For his informed efforts, Chatfield was labelled “an idiot” repeatedly under parliamentary privilege by former WA energy minister Bill Johnston in August, 2023.

Johnston, who has since shuffled off the political scene, provided no cogent argument against Chatfield’s research which showed the move away from coal was dangerously premature, WA’s intended reliance on batteries was wildly overstated and the vital backstop of abundant gas couldn’t be delivered through the constrained pipeline.

In a presentation to the Retired Engineers’ Association in February this year, Chatfield released his latest computer modelling of WA’s renewables transition, including the wind and solar droughts, he says expressly at the request of AEMO.

AEMO now appears to be listening. In the consultations leading to the draft ISP, Energy Networks Australia, representing electricity and gas distributors, also raised the issue, with the operator promising to strengthen its modelling.

“AEMO acknowledges ENA’s recommendation to enhance risk analysis in the ISP to ensure system robustness, security, and reliability under a range of conditions, including minimum system load and ‘dunkelflaute’ events,” the consultations summary said.

A report in The Australian on December 1, previewing the draft ISP, noted AEMO had been given “repeated warnings” that its methodology for forecasting risks to energy supply was underestimating the impact of wind droughts. Previously AEMO had assumed wind power would never fall below 14 per cent of its generation capacity for multiple days.

“But Australia had experienced multiple periods of wind generation well below that 14 per cent level in the months leading up to the release of that 2024 Integrated System Plan, raising concerns that AEMO’s modelling had failed to accurately reflect the reliability risks in the east energy grid,” The Australian reported.

This is what AEMO now says: “Renewable lulls are common, local weather events that typically last a few hours, a day or two, or on rare occasions a week. They are more likely in winter when there is less solar irradiation (energy) and shorter daylight hours.

“Extended renewable lulls covering wide areas are hard to predict in duration and intensity, and will become harder to predict as the climate changes.”

Chatfield argues the dunkelflaute effect is much stronger in WA because the South-West Integrated System area offers little diversity of wind availability with still conditions usually fairly widespread.

SWIS is geographically tiny compared to the NEM, which stretches from upper Queensland to Tasmania, and west to Port Augusta. There, the wind is always blowing somewhere, providing energy to the shared grid.

“In 2024, the wind farms in the SWIS produced at less than 10 per cent of their capacity for 11.3 per cent of the year, and at 10 to 20 per cent of their capacity for 14.3 per cent of the year,” Chatfield says.

“So the wind output was 20 per cent or less for 25.6 per cent of the year! The longest period for which the wind output was less than 20 per cent of capacity was 72 hours – that’s three days! The longest period for which the wind output in the SWIS was 10 per cent or less was 40 hours!

“Therefore in the SWIS when the sun has gone down and the wind generation is at less than 10 per cent of installed capacity for 40 hours, imagine what battery storage is required to maintain supply.”

On Chatfield’s calculations, to support such wind droughts with batteries alone for just a 12-hour stretch would require 87 of them, each capable of supplying 400MWh over four hours.

On the current price tag for big batteries in WA, that would cost about $27 billion.

“This requirement for 87 batteries just to survive a windless night will be reduced by the input from any other generation,” Chatfield says. “Without coal (which is to be retired) it must come from gas.

“Unfortunately, the Dampier to Bunbury gas pipeline does not have the capacity to deliver gas for 12 continuous hours to a fleet of gas turbines operating at such high loads, so the batteries will be exhausted, the gas supply limit will be reached, gas supply will be curtailed and the lights will go off.

“This won’t happen like this in the NEM because of wind diversity, and the availability of stored energy in hydro systems. WA has no stored hydro of any scale.

“The only solution for the SWIS is to leave the coal plants in service until the gas delivery capacity is increased and additional gas generation is purchased and installed. This will take several years.”

On Wednesday, I asked AEMO how a changed methodology for the NEM to handle renewables lulls would affect WA’s market, for which it does not have planning responsibility. That’s the job of the Cook Government’s Co-ordinator of Energy, Jai Thomas, who has been unable to produce a public plan.

From its guarded “on background” response, AEMO is conceding nothing about overlooking the issue previously. And offered no guidance for WA.

Which is nearly as disappointing as the Cook Government’s renewables policy dunkelflaute which lasts until 2027.