New figures show WA’s electricity grid is holding, but batteries alone will not keep the lights on.
Western Australia’s SWIS (South West Interconnected System) is facing growing reliability risks unless firm, energy-producing capacity is urgently added to complement the state’s surging battery investments, the Australian Energy Market Operator (AEMO) has warned.
According to the 2025 Wholesale Electricity Market (WEM) Electricity Statement of Opportunities, more than 500 MW/2,000 MWh of grid-scale battery storage has already been deployed, helping meet recent peak demands.
However, extreme summer heatwaves and coal retirements are stretching the system’s resilience. Peak demand has grown beyond forecast levels, now extending well into the evening – beyond the reach of most four-hour batteries.
Forecasts show a looming capacity shortfall of 932 MW by 2027–28 if additional firm supply is not secured.
Even factoring in 507 MW of “probable” but uncommitted projects, the gap stands at 425 MW. AEMO said that storage alone is insufficient.
“At least 110 MW of new generation sources such as gas, wind and solar generation will be required,” it says.
Part of the issue lies in the timing mismatch.
The Collie Power Station will close in 2027, followed by Muja D in 2029 and Pinjar gas turbines between 2029 and 2032 – removing 1.7 GW of dispatchable thermal capacity from the grid. Meanwhile, much of the committed replacement capacity is non-generating storage or demand-side response, which lacks depth for sustained high-demand events.
“While there is substantial continued interest in battery storage to help maintain reliable supply, investment in storage alone will not suffice,” AEMO stated.
Adding urgency, the Bluewaters Power Station – already excluded from AEMO’s base forecasts from 2027 due to coal supply uncertainty – has been flagged as critical to improving unserved energy outcomes. If Bluewaters remains operational past 2026, energy shortfall projections for 2027–28 improve significantly.
Sub-regional issues compound the system-wide risks. Shortfalls are expected in the Eastern Goldfields and North Country unless new supply and major transmission projects – the East Enhancements Project and Clean Energy Link-North – are delivered on time. AEMO has assumed a one-year delay for CEL-North in its modelling.
Meanwhile, rooftop solar continues to drive down minimum demand, increasing operational challenges and accelerating the need for flexible ramping capacity.
Over 1 GW of new battery storage is expected by 2026–27, but AEMO has now lifted the required storage duration for new batteries from four to six hours.
AEMO stressed that solutions must extend beyond batteries. Grid-forming technologies, synchronous condensers, and gas plants with clutches that can provide system strength even when idle are flagged as priorities to support system stability as more inverter-based renewables connect.
“More energy-producing capacity is needed to replace anticipated reductions in existing thermal generation capacity,” AEMO concluded.