Australia’s largest private utility, Origin Energy, says it has completed the last “hold point” on its second big battery project, this one located next to a gas generator that the new storage technology is rapidly pushing out of the market.

Origin says, bar a couple of final sign-offs, the 300 megawatt (MW), 650 megawatt hour (MWh) Mortlake battery in Victoria is now in commercial operation. And, like the first stages of the Supernode battery that is has contracted in Queensland, it has arrived on market ahead of schedule.

The Mortlake battery is located next to the 566 MW Mortlake gas generator, the largest in Victoria, and is a part of a rapidly growing portfolio of big batteries that Origin Energy is building and contracting to protect its position in the “firming” market – the ability to meet the demand peaks from its retail and commercial customer base.

In its annual results briefing on Thursday, Origin highlighted how battery storage is already displacing its gas generator units in responding to the demand peaks, largely because it costs less to deploy, is cleaner, and is quicker and more flexible in its response to market signals.

The Mortlake battery has been built at a cost of around $400 million. Origin is spending $1.8 billion on Mortlake and the three stages of the Eraring battery in NSW, which will be one of the country’s biggest when its final stages are complete early next year to deliver a total capacity of 700 MW and 3,160 MWh.