Mount Isa sits roughly 900 kilometres west of Townsville by road, and for as long as the mine there has been running, the town has generated most of its own power off gas because there has never been an economic case to string transmission that far from the coastal grid. That is the gap Powerlink Queensland is now trying to close with CopperString 2032, and the project has shifted from aspiration to construction commitment over the past eighteen months in a way that’s worth taking seriously, even if the final bill is still moving.
Powerlink is the Queensland government’s wholly owned transmission network service provider, the entity that owns and runs the high-voltage backbone connecting generators to the distribution networks Energex and Ergon run closer to customers. It doesn’t sell electricity to households. It builds and maintains the wires that carry bulk power around the state, regulated by the AER on the revenue it’s allowed to recover from network charges. That’s a useful distinction to hold onto, because CopperString isn’t a generation project at all. It’s an 1,100-kilometre transmission line, and transmission and generation get funded, approved and risked completely differently.
What CopperString actually is #
The project runs a 500kV-capable transmission corridor from the existing grid near Woodstock, inland of Townsville, up through Hughenden and Richmond to Mount Isa, connecting the north-west minerals province to the National Electricity Market for the first time. Queensland’s government took majority ownership of the project in 2022 after years of private development stalled on financing, and Powerlink was handed delivery in 2023. First power to Hughenden is targeted for the back half of this decade, with the full Mount Isa connection, the 2032 in the name, set against that year.
The pitch is straightforward on paper. Mount Isa and the surrounding minerals province, which produces copper, zinc, lead and increasingly critical minerals feeding battery supply chains, currently runs on isolated gas generation because there’s no economic link to the NEM. Connect it, and miners get access to cheaper, more reliable grid power plus the renewable resource of the north-west, strong solar and genuinely good wind in parts of the corridor, gets a route to market it currently lacks. Powerlink’s own project material frames it as unlocking several gigawatts of renewable development potential along the route, not just serving the existing mining load.
The cost number, and why I’d be careful with it #
Let’s be careful with that number, because CopperString’s price tag has moved more than once and the headline figure depends heavily on what’s included. Early private-sector estimates sat well under $2 billion. By the time the Queensland government took it over, the figure being discussed publicly was closer to $5 billion. Current public estimates, reflecting updated route studies, construction cost inflation and a fuller scope, sit higher again – in the order of $5 to $6 billion for the core transmission build, with total project cost depending on what generation and firming infrastructure gets bundled in alongside it.
I’d treat any single figure quoted for CopperString as a snapshot, not a settled number. Transmission projects of this scale, across remote terrain with limited existing road access, tend to reveal real costs during construction rather than during planning. The AEMO Integrated System Plan treats north Queensland transmission expansion as a priority corridor, but the ISP itself is explicit that its cost estimates for actionable projects carry wide ranges until contracts are let. Powerlink has been progressively releasing more granular contract packages through 2025 and 2026, which is the right way to de-risk a number this size – tender by tender, rather than one lump estimate carried for years.
Funding structure and who’s actually on the hook #
This is where CopperString differs meaningfully from a merchant transmission project. The Queensland government has committed equity and guaranteed debt through Powerlink’s balance sheet, with Commonwealth support layered on top via concessional finance: the CEFC and, separately, Commonwealth funding announced for north Queensland transmission more broadly. That’s a deliberate structure. A fully merchant build, recovering its cost purely from regulated transmission charges on a sparse customer base in the north-west, would struggle to pass an investment test on its own. Government ownership effectively allows Queensland to treat the project as a strategic industrial and energy security asset rather than a conventional rate-of-return investment, similar in spirit to the logic behind Queensland’s broader energy plan resting on pumped hydro and public money.
Whether that’s good public policy or an expensive insurance premium depends on your view of how much the minerals province is worth protecting against gas price exposure and ageing isolated generation. My own read is that the industrial case – keeping a genuinely significant minerals export region competitive as global copper and critical minerals demand firms up – is stronger than the pure electricity-market case on its own. Judged purely as a transmission investment recovering its cost from existing load, the numbers are harder to make work. Judged as regional economic infrastructure with electricity as the delivery mechanism, it reads differently.
Powerlink’s wider balance sheet #
CopperString is the headline project, but it isn’t Powerlink’s only large build. The company has been running a substantial capital programme tied to Queensland’s broader renewable energy zones and the connections needed for new wind, solar and storage capacity coming onto the grid through the second half of this decade, alongside augmentation work supporting the state’s coal exit. Powerlink’s annual regulatory reporting to the AER shows a capital expenditure programme that has grown considerably from historical levels, consistent with what every NEM transmission business is now facing as generation shifts from a handful of large coal units to thousands of distributed and utility-scale renewable connections.
That matters for how CopperString gets judged internally. It’s not Powerlink’s only call on capital and expertise. Transmission construction crews, specialist contractors and steel supply are all being drawn on simultaneously by Powerlink’s REZ work in the south-east and by CopperString in the north-west, and those two programmes are competing for some of the same limited resources. Readers who’ve followed the VNI West saga in Victoria will recognise the pattern – transmission timelines slip less often because of money and more often because of workforce, easements and route approvals all moving at once.
The renewable energy case along the corridor #
The north-west minerals province has resource characteristics that don’t get enough attention in the generation-siting conversation, which tends to focus on the obvious renewable energy zones closer to the coast. Solar resource in the Mount Isa region is excellent by national standards, and there’s credible wind along parts of the corridor too. Powerlink’s own modelling for the project assumes a meaningful share of the line’s eventual utilisation will come from new generation connecting along the route rather than purely serving existing mine load. If that plays out, CopperString starts to look less like a single-purpose mining supply line and more like a genuine new renewable energy zone enabler, in the same category as the New England REZ build in New South Wales, just with a smaller existing customer base and a longer, lonelier corridor.
The risk sits on the demand side, not the supply side. Generation development tends to follow transmission access reasonably reliably once a line is actually energised – developers queue up once there’s a connection point to queue for. What’s less certain is how much new mining and minerals processing load actually materialises on the schedule assumed in the business case. Global critical minerals prices move, project financing for individual mines is its own separate risk, and a transmission line sized for an assumed load growth trajectory that doesn’t fully show up leaves Powerlink, and ultimately Queensland taxpayers, carrying underutilised capacity. That’s a real possibility worth naming plainly rather than glossing over.
How this compares with other state transmission bets #
Every state with a long, thin grid has some version of this argument. Western Australia’s isolated South West Interconnected System never faces the question because it has no neighbour to connect to at all. Tasmania’s entire Battery of the Nation strategy rests on a single cable across Bass Strait actually getting built on schedule, which is its own long-running story. Queensland’s situation is closer to NSW’s REZ rollout problem: a build-out racing against both coal closures and resource development timelines, except CopperString isn’t retiring anything, it’s reaching somewhere the grid has simply never been.
I keep thinking about the comparison with transmission versus distribution ownership more broadly – who actually owns the wires matters less here than who’s willing to wear the risk of building ahead of confirmed demand. Powerlink, as a 100 percent government-owned entity with the state’s balance sheet behind it, is one of the few organisations in the NEM that can credibly make that bet. A private developer financing CopperString purely on contracted mining load would likely have needed firmer offtake commitments before turning a sod. Government ownership buys patience that a merchant model doesn’t have, for better or worse.
Where it actually stands heading into 2027 #
Construction packages for the southern sections of the route, closer to Woodstock and Hughenden, have been progressively let through 2025 and 2026, with Powerlink targeting staged energisation rather than a single big-bang connection date. That staging matters operationally – it lets early sections start carrying power and generating revenue well before the full Mount Isa link is complete, which helps the project’s cash profile and gives AEMO and the market operator time to understand how the new corridor behaves before the whole thing is live. The full connection through to Mount Isa remains pointed at the early 2030s, consistent with the project’s 2032 branding, though anyone who’s watched enough Queensland infrastructure projects run long will reasonably want to see a few more construction seasons pass before treating that date as locked.
For what it’s worth, I’d put CopperString in the category of projects that are more likely to get built than not, given the ownership structure and the political commitment behind it, but less likely to land on the exact budget or exact date currently being quoted. That’s not a criticism specific to Powerlink. It’s close to the base rate for transmission builds of this length anywhere in the NEM. The question worth returning to in a year or two is less “will it get built” and more “what actually connects to it once it is.”
– Anjali Rao, Grid & Storage Correspondent
Photo by Jose Manuel Esp on Unsplash