South Australia’s power grid has been put to the test in recent weeks, with several days of strong winds followed quickly by the state’s most severe wind drought in years.
According to Open Electricity data, after wind energy supplied 87.1 per cent of South Australia’s electricity needs on June 18, only days later on June 21, it contributed just 3.8 per cent to the state’s electricity consumption.
Gas jumped in, boosting its contribution from under five per cent of South Australia’s needs to more than 50 per cent. This led to a rapid uptick in emissions intensity, with 1272 tCO2e (tonnes of carbon dioxide equivalent) generated on June 18 rising to 23,264 tCO2e on June 21.
On the surface, this highlights a multi-pronged grid oscillating as needed. Look a bit deeper and further lessons can be learned.
Electrical engineer and Global Power Energy principal advisor Geoff Eldridge sees this as a “stress test” for South Australia’s energy system, affirming that the state’s wind transition “looks strong on the long view”.
“The one-year rolling mean for wind as a share of consumption has continued to rise over recent years, even after the well-known June 2024 wind drought,” he said in a LinkedIn column.
“But the short view says something different. The four-day rolling mean has just fallen to the lowest point in the seven-year chart set. That does not cancel the long-run trend. It tells us where the system is being examined.”
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Eldridge said that while wind was still shouldering much of the load on an annual basis, the short-run signal is “operationally serious”.
“A very low four-day wind-share period tests the resources that carry the system when wind contribution falls,” he said.
“This is why both charts matter: the one-year mean and the four-day mean. One shows progress. The other shows the stress test.”
Eldridge compared two low-wind periods (April 13–16 and June 21–24) to better understand how the energy stack was behaving.
GPE NEMLog data found wind contributed, on average, 11.9 per cent of energy consumption from April 13–16, with a 6.2 per cent average contribution from June 21–24. Gas stepped in to supply an average of 413 megawatts (MW) from April 13–16, with an average 1128MW supplied from June 21–24.
June had much higher “replacement burden” and less “net import support”, with an average of 274MW of net imports available to South Australia in June compared with 566MW in April.
“The real question is not simply how low wind fell,” Eldridge said. “It is what had to replace it, how much that replacement cost, and what parts of the system looked stretched.”
According to Eldridge, while gas became a central resource during these periods, batteries were “active but duration limited”.
“This is where the transition debate often becomes too binary,” he said. “Batteries can be valuable and still not be the whole answer to a multi-day winter lull. Gas can be essential in the event and still raise questions about emissions, fuel risk and long-term role. Interconnection can help, but only if neighbouring regions have spare flexibility when it is needed.”
The replacement stack, Eldridge said, is where the “real planning questions sit”.
Over to you, energy authorities and regulators.
