The Australian Energy Market Operator (AEMO) is expecting there to be further investment opportunities in Western Australia’s main power system over the next decade, according to its 2025 Wholesale Electricity Market Electricity Statement of Opportunities (WEM ESOO) report.
Produced annually, the 2025 reliability outlook (2025–26 to 2034–35) considers peak electricity demand growth, alongside potential new and retiring generation, highlighting the need for ongoing investment in generation, longer-duration battery storage, and network assets to support electricity security and reliability in the SWIS (South West Interconnected System).
AEMO Interim Executive General Manager Western Australia, Nicola Falcon, said since 2023, almost 500MW of battery storage has begun operating in the SWIS, with a further 728MW of committed storage expected to be online in 2025–26.
“While there has been significant investment in recent years, and ongoing interest, it is prudent to ensure the timely and coordinated delivery of projects within the pipeline.
“Over the last few years, strong investment, particularly in battery storage, has helped alleviate previously forecast risks to reliability in the state’s main power system,” Ms Falcon said.
“Looking forward, ongoing investment in generation and storage is required to manage growing peak demand and offset power station retirements,” she added.
For the 2025–26 summer, a small 50MW shortfall has been forecast, which AEMO said is less than the previous three summers. AEMO will assess the situation further before deciding if it needs to trigger another supplementary capacity procurement process.
“Supplementary capacity was successfully used over the past three summers to navigate record peak demand periods during extreme heatwave conditions,” Ms Falcon said.
In the near-term, there is a pipeline of more than 1600MW committed and probable generation and storage projects (including the aforementioned 728MW of committed battery storage) that could be online by 2027–28.
A further 2300MW of proposed capacity was submitted under the expressions of interest stage of the 2025 Reserve Capacity Cycle. AEMO said this will need to be underpinned by the planned development of Western Power’s transmission network, which is currently underway.
“As can be seen from the substantial pipeline, investment interest in the SWIS remains strong. This WEM ESOO highlights the importance of getting the right mix of generation and storage to continue providing secure and reliable electricity to the SWIS following the closure of ageing coal and gas power stations,” Ms Falcon said.
The WEM ESOO considers approximately 1700MW of ageing coal and gas power stations are expected to retire from 2027 to 2032. This includes Synergy’s Collie (coal), Muja D (coal) and Pinjar (gas) power stations, and the privately-owned Bluewaters power station (coal).
While the WEM ESOO models scenarios relating to Bluewaters’ potential early exit from the SWIS due to current uncertainty over its coal supply beyond 2027–28, a sensitivity analysis has also been undertaken that assumes Bluewaters’ continued operation until 2030–31.
