The Collie Battery Energy Storage System (CBESS) is now fully operational, marking a major step in Western Australia’s energy transition to a more flexible and reliable energy system. GHD has supported Synergy, Western Australia’s state-owned electricity generator and retailer, throughout the delivery and commissioning of CBESS helping to bring the project online safely and on schedule.  

The 500-MW / 2,000 MWh CBESS is the largest battery commissioned by Synergy and the second largest in terms of storage in Australia. Containing 640 batteries and 160 inverters, it has the capacity to power around 785,000 homes for four hours.

CBESS has played a key role in the Western Australian Government’s Energy Transformation Strategy, supporting the state’s plan to use more renewable energy in its electricity system while maintaining reliability. The project has increased Synergy’s total battery storage capacity to more than 825 MW and nearly 3, 500 MWh – surpassing the 740 MW of coal-fired power remaining at the Muja and Collie coal-fired power stations, which are scheduled to retire by the end of the decade.

Delivered through an Integrated Project Management Team structure, the project brought together Synergy and GHD specialists from a diverse range of technical and management disciplines, with GHD’s Delivery Phase Services team co-located at Synergy’s office in Perth and on-site at Collie.

This engagement builds on GHD’s previous work with Synergy on the delivery of the Kwinana Battery Energy Storage Systems (KBESS) 1 and 2 under a program partnership approach.

“Our long-term collaboration with Synergy, beginning with the Western Australian Government’s initial plans to retire coal-fired generation, has provided invaluable insight and experience in delivering large-scale battery projects,” said Jason Hyde, Project Director – Delivery Phase Services, GHD. “CBESS builds on delivery models proven at Kwinana, allowing us to refine commissioning processes and accelerate integration into the grid, ready to support the 2026 summer energy peaks.”

CBESS represents a significant expansion in Western Australia’s storage capability and provides a strong foundation for future largescale battery projects.