Inside Stanwell’s expanding energy portfolio

A few years ago, Stanwell made a decision to integrate two large-scale battery energy storage systems (BESS) into a portfolio of coal-fired generation units, as part of a broader commitment to meet Queensland’s energy needs.

At the time, the move differed from other BESS proposals – many of which were standalone projects seeking greenfield sites.

However, for Stanwell, adding the 300MW/600MWh Tarong Battery and 300MW/1,200MWh Stanwell Battery into its diverse portfolio of generation assets made perfect sense.

“By maximising asset sites and deploying the vacant land around our power stations, we knew we could help deliver battery projects faster,” said Steve Quilter, Stanwell’s Executive General Manager for Growth and Future Energy, ahead of the Queensland Energy Conference.

“We thought it was a great opportunity to show how sites can be adapted and made future resilient.”

Logistically logical

Stanwell also recognised the practical advantages of integrating batteries on its existing land.

With Tarong and Stanwell already strong connection points in the National Energy Market (NEM), they were well-positioned to accommodate further growth in storage and generation.

“Co-locating BESS projects at our power station sites meant we could capitalise our skilled workforce for ongoing operations and maintenance, that there was plenty of space and buffer zone, and that we had a simpler approval pathway because of the existing status of the sites. It was an efficient way to get these assets in,” Steve said.

From a social licence perspective, Stanwell’s move was also a drawcard.

Having operated its power stations in Rockhampton for thirty years and South Burnett for forty years, the company already had long-standing community relationships in place – and residents acknowledged the transferability of Stanwell’s safety rigour between assets.

“There is a clear and direct link between our safe, long-term operation of coal plants and the expertise required to successfully deliver and operate large-scale battery energy storage systems,” Steve said.

“Co-locating the BESS’s and leveraging our reputation for safe asset management was a positive sell and assurance to the community that we already have those issues under control and can be trusted to do the right things.

“This meant there was an efficient use of assets and resources from a social license perspective. Completing the project within an established asset, where most social licence concerns have already been addressed, was seen as a positive, as it meant we didn’t have to acquire new land or affect new neighbours.”

For batteries, this social licence is particularly important, given concerns raised in some communities about battery safety, particularly with fires.

Balancing challenges and opportunities

However, Stanwell’s diversity has also brought a range of challenges. As well as its battery portfolio, the company now also owns a gas project, has a significant solar and wind offtake portfolio, and is progressing a pumped hydro project. This diversity has forced a rethink of how the portfolio is managed.

“We’ve got basically every technology that’s commercialised in Australia in our portfolio. That then raises the challenge of what is the best way to dispatch those, how do we create value and protect our portfolio position?

“Initially, we also had to ask ourselves, why should we run a battery now instead of running the coal plant? Or one of our other assets. There’s been a fair bit of thinking into the algorithm of that, and our Energy Markets and ICT teams developed a proprietary optimiser tool for bidding the portfolio.”

Keeping up with the technology

More generally, Stanwell had to make sure the battery technology would remain fit-for-purpose as the energy landscape evolved. With advances in energy technology evolving at pace, the company knew it had to be future-focused and open to measured risk.

“We had to ensure that what we were buying was cutting edge and, therefore, still competitive and contemporary, by the time of completion.

“Things like the inverter and charging rates can advance really quickly. If you lock in the cheapest option at the time, you might later miss market opportunities because of your tech.”

To navigate this issue, Stanwell leant on its extensive market knowledge as a multiple generation asset investor.

“We thought about what the market’s doing now, what sort of future challenges it’s looking to solve.”

Prices were on its side

With this strategy in place, Stanwell’s current batteries projects have gone without a hitch. However, an earlier attempt proved unsuccessful.

“This was actually our second attempt at trying to get a battery project underway. In the first one, we couldn’t find the commercial opportunity for it.
But the fall in battery costs has worked in our favour.

“It’s one of the few instances where we’ve seen the rhetoric on falling costs has actually turned into reality and that helped get the Tarong and Stanwell projects over the line.”

In fact, the price drop was so great that Stanwell’s original proposal for two 150 MW batteries – one at each of its sites – eventuated in a 300 MW 2 hour and a 300 MW 4 hour, over a short period.

“It was all because of the affordability of main components,” Steve said.
With affordability now on its side, Stanwell’s major battery projects are scheduled to become operational between December 2025 and mid-2027.

The 300MW/600MWh Tarong Battery is now in full operation, while the 300MW/1,200MWh Stanwell BESS near Rockhampton is expected to be fully operational by mid-2027.

The company also has a 15‑year Capacity Purchase Agreement (CPA) with Quinbrook for 100% of the stored energy of the Supernode BESS Stage 3 at Brendale in Brisbane’s north.

Further insight

Sharing more on these projects, Steve will present at the upcoming Queensland Energy Conference, held in Brisbane.

This year’s event will take place 4-5 March at the Amore Hotel.

Learn more and register your tickets here.