Western Australia’s Regional Joint Development Assessment Panel has approved Synergy’s plans to construct a 500 MW, four-hour battery energy storage system near the coal town of Collie and has also provided a green light for infrastructure approvals to support a possible expansion to 1,000 MW/4,000 MWh.

Synergy plans to build the AUD 1.6 billion ($1.05 billion) Collie Battery Energy Storage System (CBESS) approximately 200 kilometers southwest of the state capital of Perth, just north of the existing coal-fired Collie Power Station that is set to be retired by 2027.

The first stage of the proposed development will comprise the installation of two 250 MW/1,000 MWh ‘sub facilities’ featuring 656 battery enclosures, 164 inverters and up to four 330/33kV transformer units.

The CBESS will connect via the existing Shotts Terminal to the South West Interconnected System (SWIS), the electricity grid that supplies power to Perth and more than one million homes and businesses between Geraldton and Esperance and east to Kalgoorlie.

Synergy said the battery will help provide the state’s power grid with the capacity it needs to remain reliable and affordable as the state moves towards emissions-free power generation in 2030.

“The proposal is pivotal to Synergy’s energy transition program and represents a generational opportunity to support carbon emissions reduction and secure energy supply,” the application reads.

While no date has been given for the start of construction, Synergy said it is expecting the battery to commence the commissioning process in October 2025.

The Collie BESS is the third grid-scale battery being built by Synergy in southwestern Western Australia.

The government-owned energy generator and retailer has already completed construction of the 100 MW/200 MWh Kwinana battery energy storage system about 30 kilometers south of Perth and has started work on a new 200 MW/800 MWh big battery being built adjacent to that facility.

French renewables giant Neoen is also in the process of building a 1 GW/4 GWh battery in Collie as the state government seeks to ramp up energy storage capacity to support its planned transition from coal-fired power to renewables.

Neoen started construction of its Collie battery in June, about the same time the company was awarded a contract by the Australian Energy Market Operator (AEMO) to provide almost all of the project’s first-stage capacity to help smooth the state’s solar duck curve.