Drive the Jones Hill Road turnoff west of Imbil in the Sunshine Coast hinterland and you’ll hit the Borumba construction camp before you hit much else. Dongas, site offices, a boom gate with a guard who’s clearly answered the “so when’s it finished” question too many times. That’s the physical end of Queensland’s energy plan right now: a hole being dug in the Mary Valley that’s supposed to anchor a grid that still gets about half its generation from four coal power stations.
Queensland’s approach to the transition is genuinely different from every other state on the NEM, and it’s worth being precise about why. It isn’t just that the government owns most of the generation fleet – Tasmania can say something similar with Hydro Tasmania. It’s that Queensland has bet its firming strategy almost entirely on one technology, pumped hydro, built and owned by state corporations, at a scale nobody else in the country is attempting. That’s a bold position. It’s also a fragile one if the timeline slips, and the timeline has already slipped once.
The two pillars, and why they’re load-bearing #
The plan as Queensland’s energy department and Energy Minister have described it publicly rests on two things. First, pumped hydro at a scale that dwarfs anything else proposed in the NEM: Borumba at 2GW, Pioneer-Burdekin shelved by the former government but still lurking in planning documents, and Kidston already operating at a smaller scale near Georgetown. Second, public ownership of the generation and poles-and-wires businesses that deliver it, through Queensland-owned entities like CleanCo, Stanwell and Powerlink.
I’ve written before about where Borumba actually stands against its original schedule, and the short version, without repeating myself, is that the project has moved from “under construction on the original timeline” to “under construction with a later commissioning date and a materially higher cost estimate than the 2022 figures.” That’s not a scandal. Big pumped hydro projects worldwide run long; Snowy 2.0 is the local cautionary tale everyone in this sector now cites by reflex. But it does mean the second pillar of Queensland’s plan, the public-ownership one, is currently carrying more of the weight than the first pillar was designed to carry on its own.
What pumped hydro actually buys you, in MW and MWh terms #
Let’s be careful with the numbers here, because pumped hydro gets talked about loosely even by people who should know better. Borumba’s headline figure is 2GW of capacity. That’s power, the rate at which it can discharge. The energy figure, how long it can sustain that output, is what actually determines whether it’s solving a daily firming problem or a multi-day drought-of-wind problem. Public documents from Queensland Hydro put Borumba’s storage duration at roughly 24 hours at full output, which is an entirely different animal to the two-hour duration you get from most grid-scale batteries currently connecting to the NEM.
That duration is the whole investment case. A battery like the Waratah Super Battery in NSW is brilliant at absorbing a five-minute frequency event or smoothing an afternoon ramp – I’ve covered what that project is actually earning its keep doing. Borumba is aimed at something slower: the week where Queensland’s wind resource goes quiet and solar underperforms behind cloud cover for days running, and the state needs deep, dispatchable energy rather than just fast power. AEMO’s Integrated System Plan treats this distinction as central to the whole NEM transition, and Queensland’s plan is one of the only state strategies that takes “duration” as seriously as “capacity” in its own public messaging.
Public ownership: the argument for, and the argument that gets glossed over #
The case for keeping generation in public hands in Queensland isn’t mysterious. State-owned Stanwell and CleanCo can build and hold assets that wouldn’t clear a private investor’s hurdle rate on dispatchable-but-rarely-used plant, because the state’s cost of capital is lower and its investment horizon is longer than a listed gentailer answering to quarterly guidance. That’s a genuine structural advantage, and I’d argue it’s the strongest reason Queensland’s model deserves more credit than it gets outside the state. The debate over which ownership model actually builds faster is live across the whole NEM and I don’t think either side has it fully right, but Queensland’s experience adds real data to that argument, not just ideology.
The part that gets glossed over in the government’s own messaging is that public ownership doesn’t automatically mean public cost discipline. Borumba’s cost estimate has moved, CopperString’s has moved, and both are now effectively Queensland Treasury’s problem rather than a private developer’s problem to absorb or walk away from. That’s a trade-off, not a free lunch. If Borumba lands at a materially higher cost than first flagged, Queensland households and the state budget carry that, not a shareholder register in Melbourne or Sydney.
Coal still does the heavy lifting, and that’s the actual clock #
Here’s the number that actually sets the pace of Queensland’s plan: the state’s four coal-fired power stations (Gladstone, Stanwell, Callide and Tarong) still supply the bulk of Queensland’s electricity on an average day, and none of them has a legislated closure date as firm as Victoria’s for Yallourn or NSW’s for Eraring. That’s actually an advantage for sequencing, in one sense; Queensland isn’t racing a hard deadline the way NSW is trying to time its coal exit against its REZ rollout. But it also means the state has less external pressure forcing Borumba, CopperString and the firming fleet to actually hit their dates. Deadlines concentrate minds. Queensland’s coal fleet retiring “sometime in the 2030s, flexible” doesn’t concentrate anyone’s.
I think that soft deadline is underappreciated as a risk in itself. A hard closure date, however brutal, forces replacement capacity to be ready on a specific day. An open-ended one lets a pumped hydro project slip a year, then slip again, with no single moment where the lights visibly depend on it. That’s precisely the dynamic AEMO’s reliability forecasting tries to flag early, state by state, in its annual Electricity Statement of Opportunities.
CopperString and the other half of the grid story #
Pumped hydro and coal retirement dominate the headlines, but Queensland’s other big infrastructure bet is transmission: CopperString, Powerlink’s line to connect the north-west minerals province and open up renewable zones that currently sit stranded behind thin wires. Without that build, a lot of the wind and solar resource in the state’s north has nowhere useful to send its output, and Borumba’s southern location doesn’t help load in the north anyway. The two projects are more connected than the public conversation usually treats them: a pumped hydro fleet in the south-east and a transmission backbone to the north-west are solving different halves of the same problem, and Queensland needs both running roughly on schedule for either to deliver its full value.
Where this leaves the state, honestly #
I don’t think Queensland’s plan is wrong in its bones. Deep storage duration is a genuine gap in the NEM’s current firming mix, which leans heavily on two-hour batteries and gas peakers – I’ve compared those two options directly before, and neither solves the multi-day problem the way long-duration pumped hydro can. Public ownership gives Queensland the balance sheet to build that kind of asset when a private developer might reasonably decline the risk. Those are real strengths.
But a plan built on two pillars is only as strong as its weaker pillar, and right now that’s timeline discipline. Borumba has already cost more and taken longer than first promised. If that pattern repeats on CopperString, or if coal units start showing their age faster than Treasury’s models assume, and ageing coal plant has a habit of doing exactly that – Queensland could find itself relying on a pumped hydro fleet that isn’t ready and a coal fleet that’s past its best, at the same time. That’s not a prediction. It’s the scenario the state’s own planning needs to be weighed against, honestly, rather than taken on faith because the ownership structure happens to be public.
Worth watching whether the next Queensland budget update treats Borumba’s cost and schedule as settled, or admits there’s still room for both to move again. On past form, I wouldn’t bet the house on “settled.”
– Anjali Rao, Grid & Storage Correspondent