Origin Energy has officially commissioned its $400 million Mortlake Battery Energy Storage System (BESS) in south-west Victoria, marking a significant milestone for the state’s energy transition. The 300MW/650MWh battery, located at the Mortlake Power Station, commenced commercial operations on September 7, 2026, bolstering grid stability and increasing the firming capacity for Victoria’s expanding renewable energy fleet.
The completion of the Mortlake Battery, nearly two years after construction commenced, integrates large-scale battery storage and advanced grid-forming capabilities directly into the Victorian electricity network. This development is crucial as the state moves towards its renewable energy targets and the planned retirement of coal-fired power stations, such as Yallourn by 2028.
Mortlake’s Role in Victoria’s Energy Future
The Mortlake BESS stands as a critical piece of infrastructure designed to manage the intermittency of renewable generation. By storing surplus electricity during periods of high solar and wind output and discharging it when demand peaks or renewable generation dips, the battery will help smooth supply and maintain consistent power for homes and businesses. Origin’s Executive Generation Manager, Andrew Thornton, highlighted the battery’s importance:
“The Mortlake battery will play an important role in supporting the security of the grid and firming the growing volume of renewable energy in south-west Victoria, so we can keep delivering reliable energy supply for households and businesses.”
The project incorporates grid-forming inverters, a technology vital for modern grids. These inverters can autonomously stabilise the grid by providing essential services like synthetic inertia, traditionally supplied by large spinning generators in coal or gas plants. This capability is increasingly important as more inverter-based renewable energy sources connect to the network. Readers interested in how new inverter rules impact the grid can find more information in our guide: Australia’s New Solar Inverter Rules 2026: Slash Export Limits by Up To 85% Without a Smart Inverter.
Key technologies deployed at Mortlake include battery systems supplied and installed by Fluence Energy, with SMA providing the critical grid-forming inverters. Civil and electrical works were delivered by RJE Global, and AusNet managed the grid connection assets.
Investment and Broader Context
Origin Energy approved an investment of approximately $400 million AUD for the Mortlake project in January 2024. The project also received conditional grant funding from the Australian Renewable Energy Agency (ARENA) through its Large-Scale Battery Storage Funding Round, underscoring the federal government’s commitment to accelerating utility-scale energy storage.
This 300MW/650MWh addition forms part of Origin’s substantial portfolio of owned and contracted grid-scale batteries, which totals 1.3GW/4GWh across Australia. Other significant projects in their portfolio include the Eraring BESS in NSW and the Supernode project in Queensland. The Mortlake Power Station itself remains Victoria’s largest gas-fired power station, with a generation capacity of 566MW, making the co-location of the battery strategic for grid services.
The Growing Role of Grid-Scale Batteries
The commissioning of the Mortlake battery aligns with a national trend of increasing investment in large-scale energy storage. The Australian Energy Market Operator (AEMO) has consistently highlighted the critical role of BESS in maintaining grid reliability and integrating the growing share of renewable energy. For instance, AEMO’s Q1 2026 Quarterly Energy Dynamics report noted that batteries more than tripled their daytime-to-evening energy shifting, delivering 1,115 MW into the evening peak across the National Electricity Market (NEM).
This rapid expansion of grid-scale batteries is essential to support the decarbonisation of Australia’s electricity supply and to prevent future reliability gaps as traditional baseload generators retire. The ability of these large batteries to respond in milliseconds to grid fluctuations helps prevent outages and ensures a stable power supply for consumers. For households concerned about power disruptions, understanding grid resilience is key: Power Outage Preparedness 2026: Your $4,350+ Australian Home Resilience Guide.
Mortlake Battery Specifications
| Feature | Specification |
|---|---|
| Capacity | 300 MW |
| Energy Storage | 650 MWh |
| Investment | Approximately $400 million AUD |
| Location | Mortlake Power Station, South-West Victoria |
| Technology | Fluence Energy (battery), SMA (inverters) |
| Commissioned | September 7, 2026 |
| Key Feature | Grid-forming inverters for system strength |
The completion of the Mortlake Battery demonstrates the accelerating pace of Australia’s energy transition, with tangible infrastructure coming online to support a more resilient, renewable-powered future for Victorian households and businesses. The facility’s strategic location and advanced capabilities position it as a cornerstone for maintaining energy security in the region for years to come.