Fancy a Model? Wait Till She Moves In

Weather-dependent power systems are beautiful in theory — capricious in practice.

There is a hint of divine comedy in it all. At the very moment Australia’s power system operator delivered its plan for stress-testing a renewables-heavy grid against an extreme wind drought, the real weather delivered a doldrum that blew past its worst-case scenario.

It was as if Zeus had decided to remind the planners how little command mortals have over the winds, and how foolish it is to mistake a model for reality.

Yet we seem fated to live in a real world governed by people who prefer a fantasy. From projections of what carbon emissions will do to the weather, to models that show more wind and solar will cut electricity bills, our politicians cling to the neat certainty of imaginary numbers rather than deal with the unruly and unpredictable world outside.

But every now and then the real world intrudes, and we owe a debt of gratitude to Queensland-based Global Power Energy for the latest reality check.

This specialist energy company did something that’s too often missing in the debate about the electricity transition: it didn’t model the weather, it measured it. And that scientific process proved, again, that observation trumps assumption.

The company showed that in the same month the Australian Energy Market Operator released its model for a worst-case future wind drought last year, real wind generation collapsed to barely half that level.

It exposed that, under those conditions, the operator’s plans for building resilience into a highly weather-dependent electricity system would fail, risking blackouts across the east coast.

The company’s chief executive, Greg Elkins, was once manager of generator connections for AEMO, responsible for assessing, approving and integrating every new power plant into the eastern grid. His company strongly supports the energy transition, but he believes it has a moral obligation to point out what is a critical gap in the system planning.

“If in God we trust and everyone else brings data, then using AEMO’s own methodology for how that data should be used shows a national security-sized risk,” Elkins told this column.

“There needs to be a national discussion on how to manage renewable fuel shortages in our climate changed future.”

The problem is buried in an appendix of the market operator’s Integrated System Plan, which plots the road map for how the eastern national electricity market will work as coal-fuelled power is largely replaced with generators that run on wind and sunshine.

The operator’s latest plan was released in June 2024 and it explicitly addresses the risk of long-run wind and solar droughts that most likely will fall in winter.

“The national electricity market must be resilient in its capability to provide energy in all weather conditions, including when there is minimal or no sunshine or wind for prolonged periods,” it says.

It then modelled a worst-case scenario by isolating “a historical severe dark and still weather event observed in June 2019” – where only 14 per cent of available wind capacity was producing power – and projecting that across eight days. The operator’s plan for the backup generation needed under these extreme conditions was built around that assumption.

But when the system plan was released on June 26, 2024, the weather in the real world was delivering a far deeper wind drought than its worst-case model assumed.

Global Power Energy mapped what happened to southern wind generation through autumn and winter last year. From mid-April the wind collapsed to about 6 to 11 per cent of generation capacity, with a run of seven consecutive days in that band. From May 12 to 16 , wind generation stayed deeply depressed, hovering around 10 per cent for five days straight. Between May 22 and 27, southern wind generation slumped into one of its deepest lulls, sitting between 4 and 8 per cent for six straight days.

From mid-June through mid-July, the wind repeatedly slumped below the market operator’s 14 per cent extreme line, with multiple dips under 10 per cent – including deep troughs around June 13, June 18 and June 21-22, along with days below 14 per cent, on July 1 and July 12-13 – before beginning to strengthen in the second half of the month.

The market operator’s modelling shows that during a multi-day wind drought the system drains its backup supplies in a predictable order.

Short-duration batteries run flat first because they can shift energy for only a few hours and can’t recharge once wind and solar collapse. After that, the grid leans on longer-duration storage such as pumped hydro and other multi-hour batteries, which begin to run down steadily over the first several days.

As those reserves fall, gas generators must run flat out, but winter gas demand means the pipeline system cannot always supply enough fuel – forcing stations to switch to diesel stored on site. AEMO assumes every new gas unit will carry 14 hours of diesel in tanks, and its modelling shows southern gas plants would burn the equivalent of 30,000 litres of diesel in a single extreme day to keep the lights on.

In short: even in the operator’s best-case scenario, a renewables-based grid survives long wind and solar droughts only by relying on gas and large volumes of diesel stored in tanks beside the generators. But the real-world data shows this plan is undercooked because the system it imagines could not withstand the weather we actually get. The stress test failed before it was even published.

Elkins says this exposes Australia to unacceptable risks. “The gas pipeline is not big enough to cover this shortfall,” he says. “Building three to four times more renewables to cover this gap does not seem logical, cost effective or practical. That’s just building more generation we won’t have any fuel for.” It also underlines the risks of building a weather-dependent grid when future weather cannot be modelled.

“AEMO, the entire energy sector, we all agree we need to design a future grid that is capable of managing renewable fuels short­ages,” Elkins says. “So what are we going to do? Hope we don’t have a fuel shortage worse than 2024 in a climate-changed 2040, 50 or 60? The science has been telling us for more than 25 years that we must plan for a changed climate.”

The irony is, from the moment humanity first burned wood, we have used fossil fuels to protect ourselves from the fury of the weather. Now, just as many warn the climate will become more extreme, we are rebuilding our entire power system on the whims of wind and sunshine.

It has the feel of an Icarus moment: a civilisation convinced it can defy gravity, only to discover the wax melts in real sunlight.

This article was first published in The Australian. Graphic: Global Power Energy.