Collie Battery Energy Storage System in Western Australia
At a glance
We supported Synergy in delivering the Collie Battery Energy Storage System (CBESS), the third large-scale lithium-ion battery within the South West Interconnected System (SWIS), Western Australia’s main electricity grid, supporting the state’s transition away from coal-fired generation. CBESS strengthens grid stability, supports renewable integration and increases Western Australia’s energy storage capacity.
Battery energy storage systems
The challenge
Western Australia’s energy system continues to transition toward higher levels of renewable generation within the SWIS. As renewable energy penetration increases, system operators must manage greater variability in generation driven by changing weather conditions and seasonal demand patterns.
These conditions place increasing pressure on system stability, particularly during peak demand periods. Maintaining reliable electricity supply requires continuous balancing of supply and demand while responding to rapid changes in renewable generation output.
As part of the State Government’s Energy Transformation Strategy, Synergy, Western Australia’s largest electricity generator and retailer, delivered a series of large-scale battery energy storage projects to support the transition of the state’s energy system.
Following the successful delivery of Kwinana Battery Energy Storage System Stage 1 (KBESS1) in 2023 and Kwinana Battery Energy Storage System Stage 2 (KBESS2) in 2024, both supported by GHD under a program partnership approach, CBESS was developed as the next major utility-scale storage asset within the SWIS.
Our response
Planned to deploy approximately 640 battery modules, each equivalent in size to a shipping container, alongside 160 inverter units, CBESS was intended to support grid stability on the SWIS by absorbing excess solar power during the day and releasing it during periods of high evening demand. The system was also expected to provide rapid charging and discharging capability to help dampen minute-to-minute fluctuations in renewable electricity generation.
Synergy engaged GHD to support this important project from early planning through to delivery, commissioning and handover to operations. The CBESS project was executed through an Integrated Project Management Team (IPMT) delivery model, using a schedule-driven and collaborative approach to support operational readiness aligned with early 2026 summer peak demand periods.
As the Delivery Partner and Engineering Services Provider, GHD, as part of the Synergy-GHD IPMT, provided comprehensive services including:
- Project management
- Environmental and regulatory approvals support
- Engineering management and design
- Preparation and coordination of engineering and design documentation aligned to the CBESS procurement strategy
- Procurement support, including logistics and inspection of major equipment
- Contract management
- Construction management
- Coordination of pre-commissioning, commissioning and start-up activities with contractors
- Project controls and reporting
- Quality assurance and project compliance management
- Document control for accuracy and accessibility of project documentation
The strong alignment between Synergy and GHD teams, combined with operational agility and responsiveness to project needs, enabled both organisations to act as delivery partners and support successful execution of this time-critical project.
The impact
Commissioned in January 2026, CBESS was strategically brought online to align with Western Australia’s summer peak demand period, strengthening system resilience at a critical time of the year.
The project plays a key role in enabling the state’s transition away from coal-fired generation by increasing the SWIS’s capacity to integrate and optimise renewable energy. Through fast-response energy storage, CBESS helps manage intra-day variability in solar generation, shifting excess daytime energy into the evening peak and supporting system stability as demand intensifies.
At a network level, the asset enhances dispatch flexibility and reliability, providing essential system support services that underpin secure operation of the grid as coal-fired generation retires and renewable penetration increases. This strengthens the overall capability of the SWIS to accommodate additional large-scale renewable investment.
CBESS also contributes to the economic transformation of Collie, as CBESS created local construction employment opportunities and supported the retraining of local workers in new energy technologies.