Borumba Dam sits about 90 kilometres northwest of the Sunshine Coast, in the Imbil State Forest. It’s not a name most Queenslanders know. By the mid-2030s, if the state government’s timetable holds, it will be the site of the largest pumped hydro project ever attempted in Australia — 2,000 MW of dispatchable capacity and up to 48,000 MWh of storage, according to the Queensland Energy and Jobs Plan published by the Queensland Department of Energy and Public Works.
Let’s be careful with that number. 2,000 MW is a power figure — the rate at which Borumba can push electricity onto the grid at peak demand. The 48,000 MWh is energy — how long it can sustain that output before the upper reservoir empties. At full discharge, that’s 24 hours. Most pumped hydro projects in the NEM operate over shorter cycles, so Borumba is designed for a different job: multi-day buffering when Queensland’s wind and solar output runs low for an extended stretch. That’s a distinct ask from a four-hour battery.
The Queensland Energy and Jobs Plan in outline #
The state government released its Queensland Energy and Jobs Plan in September 2022. The core architecture hasn’t changed since: get to 80 per cent renewable electricity by 2035, close the remaining coal fleet in an orderly sequence, and keep the state-owned generation and network businesses — CS Energy, CleanCo, Energex, Ergon, and Powerlink — at the centre of that transition rather than privatising them.
That last part matters. Queensland made a deliberate political choice after watching South Australia’s electricity price spike in the years following its coal exit. The Palaszczuk and then Crisafulli governments, despite sitting on opposite sides of politics on most things, have broadly maintained the position that publicly owned dispatchable assets are the backstop. I reckon the logic is defensible, even if it creates some awkward questions about capital allocation that I’ll come back to.
The coal exit schedule, as the plan describes it, runs from the 2030s through to around 2035 for the last units at Callide and Tarong. Kogan Creek, operated by CS Energy, had its own timeline complications following the 2021 turbine fire — a separate saga. The plan doesn’t pretend this is easy. Losing several gigawatts of synchronous generation in a decade requires firm replacement, and that’s exactly what Borumba and the proposed Pioneer-Burdekin pumped hydro scheme are meant to provide.
Borumba: what we know and what’s still open #
The detailed business case for Borumba Pumped Hydro was completed by CleanCo Queensland and published in late 2023. The headline cost estimate at that point was in the range of $12 billion, though the project team flagged that number remained subject to refinement as tunnel and civil design advanced. Construction was expected to take around eight years from a final investment decision.
That timeline puts first power sometime in the early 2030s — tight against the coal exit schedule if anything slips. And things slip in large civil infrastructure. Snowy 2.0 is the obvious reference point: costs have moved well past the original estimate and the commissioning date has shifted more than once. The Queensland government has publicly acknowledged that lesson, pointing to Borumba’s relatively simpler single-reservoir raise design compared to Snowy’s underground cavern approach. Whether that confidence is warranted will only be known in retrospect.
For a deeper look at how pumped hydro stacks up against utility-scale batteries for firming the grid, the comparison is genuinely more nuanced than the headline specs suggest — this piece on pumped hydro versus big batteries works through the economics and the different use cases in some detail.
Pioneer-Burdekin: bigger, later, and much less certain #
Borumba is the near-term project. Pioneer-Burdekin is something else entirely. The concept involves a new upper reservoir in the ranges behind Mackay, connected to an expanded Eungella Dam, with a generating capacity that AEMO’s 2024 Integrated System Plan — the 2024 ISP — identifies as potentially up to 5,000 MW. That would make it, by power output, the largest pumped hydro scheme on earth if built to that scale.
The Queensland government has invested in early-stage feasibility studies, but Pioneer-Burdekin is a long way from a final investment decision. The geological and environmental complexity is significant. The capital cost at that scale would be extraordinary. And AEMO’s 2024 ISP, which I’d recommend reading directly, identifies it as a potential long-term option rather than a committed project on the path to 2035. Let’s be careful with any framing that treats Pioneer-Burdekin as a near-term solution — it isn’t, and the plan’s own documents don’t claim it is.
The AEMO 2024 Integrated System Plan is the primary reference for understanding how projects like this fit the NEM’s broader trajectory. It’s dense, but the Queensland sections are worth the effort if you want to understand the sequencing logic.
The public ownership question #
Queensland is unusual in the NEM. Its major generators — CS Energy and CleanCo — are government-owned corporations. Its networks — Energex in the south-east and Ergon in regional Queensland — are also state-owned. Powerlink runs the transmission backbone. This means the state has direct control over investment decisions in a way that New South Wales and South Australia, having privatised most of their generation assets in earlier decades, simply don’t.
The argument for this model during a transition is obvious: a government-owned generator can absorb the long construction timeline and uncertain revenue of a pumped hydro project without needing a merchant revenue stack that would satisfy a private equity investor. The counter-argument is equally obvious: state balance sheet exposure is real, and if Borumba runs over budget by 30 per cent — which is not an implausible outcome for a large civil project — Queensland taxpayers wear it.
There’s also a market design tension. CleanCo holds a mandate to develop new renewables and firming, but it operates in the NEM alongside privately-owned generators. If the state-owned entity can access capital at lower cost and accept lower returns, that shapes the competitive landscape in ways that are worth watching. The Australian Energy Regulator’s annual State of the Energy Market report tracks this kind of structural question, though it doesn’t resolve it.
My honest read: the public ownership model is probably the right call for Queensland specifically, given the scale of what’s needed and the speed required. But it only works if the governance is genuinely commercial and the projects are held to rigorous cost discipline. Snowy 2.0 was also a government project. The ownership structure didn’t prevent cost and schedule drift.
Rooftop solar and the daytime oversupply problem #
Queensland has one of the highest rates of rooftop solar penetration in the world. On a sunny winter’s day, rooftop generation can push wholesale prices negative across the middle of the day, which is genuinely remarkable and creates real problems for grid management. AEMO has had to curtail rooftop solar in Queensland on multiple occasions — not because there’s too much solar in principle, but because the grid lacks the storage and demand flexibility to absorb it all at once.
This is where the firming story and the storage story connect. Borumba’s value isn’t just in the evening peak or multi-day weather events; it’s also in absorbing the midday surplus that rooftop solar is already producing at scale. If you’ve been following Australia’s rooftop solar trajectory, Queensland’s numbers are consistently at the top of the table.
The Distribution Annual Planning Report published by Energex gives a clear picture of how the network is already managing the two-directional flows that rooftop penetration creates. That document is less glamorous than a pumped hydro announcement, but it describes the engineering reality underneath the headlines.
Where the coal exit actually gets difficult #
The hardest part of Queensland’s plan isn’t the megawatts. It’s the people. Callide, Tarong, and Kogan Creek are located in regional communities — Biloela, Nanango, and Miles respectively — where the power stations are major employers and the surrounding economy is built around them. The Queensland Energy and Jobs Plan explicitly addresses this with worker transition commitments, including retraining programmes and early retirement options for workers over a certain age.
Whether those commitments survive contact with the actual closure dates is a question worth tracking. The Hunter in New South Wales offers a partial comparison. And for context on how the NEM’s capacity market mechanisms are meant to support the transition — including in Queensland — the debate around the Capacity Investment Scheme is directly relevant to whether new firming assets get built in time.
Queensland’s plan is, in broad terms, the most coherent state-level energy transition blueprint in the NEM. It names the assets, names the owners, and sets a timeline. Whether Borumba is commissioned before Callide closes, whether Pioneer-Burdekin ever reaches a final investment decision, and whether the public balance sheet can absorb the capital at scale — those are the open questions that will define whether it works. I’ve been watching the Borumba feasibility process closely for the past year, and the engineering confidence seems genuine. The project schedule is the thing I keep coming back to.
The dam is real. The timeline is tight. Somewhere in a Sunshine Coast hinterland valley, the hard yards are about to start.
— Anjali Rao, Grid & Storage Correspondent
Photo by Chad Nathan on Unsplash