Technology group Wärtsilä will deliver the fourth expansion stage of the Eraring battery energy storage facility at Origin Energy’s Eraring Power Station in New South Wales, adding 360 megawatt hours (MWh) of capacity and lifting the project’s total size to 700 megawatts (MW) and 3,160 MWh. Once complete, Eraring will remain the largest battery project in Australia and among the largest globally.
The Stage 4 expansion is scheduled to begin construction in December 2025 and is expected to be completed in early 2027. Wärtsilä recorded the order for the latest phase in the fourth quarter of 2025, continuing a multi-year build-out of the site.
Wärtsilä is delivering the project for Origin Energy, which owns and operates the Eraring Power Station. The companies have worked together on all phases of the battery’s development, with Wärtsilä selected for Stage 1 in 2023 and for Stages 2 and 3 in 2024. The new stage will use Wärtsilä’s modular Quantum energy storage system, supported by the company’s GEMS Digital Energy Platform and a long-term service agreement.
The expansion is intended to support the reliability of Australia’s National Electricity Market as renewable generation increases and coal-fired capacity is progressively retired. Connected directly to the NEM, the Eraring battery provides grid services such as frequency control, firming capacity, and system strength, helping to stabilise the system during periods of variable wind and solar output.
As battery projects move into the gigawatt-hour scale, managing system complexity has become increasingly important. Wärtsilä says its digital platform is designed to optimise performance and reliability across large fleets of assets, allowing operators to extract greater value from long-duration storage.
Wärtsilä Energy Storage President Tamara de Gruyter said the latest expansion reflects the growing role of large-scale batteries in enabling renewable-dominated power systems. With Stage 4 underway, Wärtsilä’s total deployed and contracted energy storage capacity in Australia now exceeds 5.8 gigawatt hours, reinforcing the country’s position as a global leader in grid-scale battery deployment.
