Victoria’s Second-Largest Big Battery Poised to Charge up, Next to the State’s Biggest Gas Generator

Why It Matters

The Mortlake battery bolsters grid reliability while enabling higher renewable penetration, a critical step in Australia’s energy transition.

Key Takeaways

• Mortlake BESS rated 300 MW, 650 MWh capacity
• Connected to AEMO MMS, showing initial integration
• Located beside Victoria's 566 MW Mortlake gas plant
• Origin's storage portfolio will reach 1.7 GW soon
• Battery supports grid stability and renewable integration

Pulse Analysis

Australia’s big‑battery race is gaining momentum, and Origin Energy’s Mortlake project exemplifies the shift toward co‑locating storage with conventional generation. By installing a 300 MW, 650 MWh battery next to the state’s largest gas‑fired plant, Origin taps into existing transmission corridors and land assets, reducing infrastructure costs while creating a flexible resource that can respond within seconds. This strategic siting not only maximizes asset utilization but also provides a buffer for the intermittent output of wind and solar farms feeding the National Electricity Market.

Technical integration is now underway as the Mortlake BESS appears on AEMO’s Market Management System. Initial pulse testing has verified inverter response and communication protocols, essential steps before scaling to full output. The system’s rapid rate of change—120 MW per minute—offers grid operators a powerful tool for frequency regulation and contingency support. Such capabilities are increasingly valuable as the NEM incorporates higher shares of renewable generation, demanding faster, more precise balancing services.

From a business perspective, Mortlake is a cornerstone of Origin’s broader storage ambition, which aims to reach 1.7 GW across owned and tolled projects by year‑end. This expansion positions the company as a leading gentailer in a market where battery storage is becoming a core revenue stream through ancillary services, capacity markets, and renewable firming contracts. As policy incentives tighten and decarbonisation targets accelerate, large‑scale batteries like Mortlake will be pivotal in delivering reliable, low‑carbon power and unlocking further investment in Australia’s clean‑energy future.