$12.7 billion. That’s the revised cost estimate AEMO’s latest Integrated System Plan attaches to the committed and anticipated transmission projects needed to keep the grid together through the 2030s, and it’s already climbed from earlier drafts. Every time that number moves, someone asks the obvious question and gets a vague answer. Who actually pays for it?
The official line is that transmission is a shared national asset, so the cost gets shared nationally. That’s technically true and practically misleading. The regulatory mechanics mean the bill lands on electricity consumers through their network charges, state by state, project by project, with very little correlation between who benefits from a line and who’s handed the invoice for it.
I’ve spent a fair bit of this year going back through AER determinations and state energy department submissions trying to find the clean version of this story. There isn’t one. What there is instead is a cost-recovery system built for a grid that no longer exists, straining to allocate expenses for a build-out it was never designed around.
The regulated asset base mechanism, plainly #
Transmission companies like Transgrid, Powerlink and AusNet don’t fund new lines out of retained earnings and hope for the best. They build the asset, the AER approves it into the regulated asset base, and then network charges recover the capital cost plus an allowed rate of return over decades. It’s a sound mechanism for a stable grid with predictable load growth. It was built in an era when transmission additions were incremental: a new substation here, a line upgrade there.
The Renewable Energy Zone programme is not incremental. NSW alone is trying to stand up several zones simultaneously, and the AEMO Integrated System Plan treats this scale of transmission build as the central spine the rest of the transition hangs off. When you drop that much capital into the RAB mechanism all at once, the charge sheet that flows out the other end gets correspondingly large, and it gets large on a timeline households don’t control and mostly didn’t vote for directly.
Here’s where the “shared national asset” framing starts to wobble. Transmission is built in a state, regulated partly by state frameworks and partly by the AER, and recovered through network tariffs that are overwhelmingly local. A Queensland consumer pays for Queensland transmission. A Victorian pays for Victorian transmission. The idea of a single national transition cost being spread evenly across 26 million people is a nice slogan. It isn’t how the invoice actually works.
NSW is carrying a weight Queensland isn’t #
Compare the exposure. NSW is trying to close coal fleet on a tighter schedule than its REZ rollout can comfortably match – I’ve written before about how NSW’s coal exit is outrunning its REZ build, and that mismatch isn’t cosmetic. It means NSW consumers are funding both the transmission to unlock new generation and, increasingly, the firming capacity to cover the gap while that transmission catches up.
Queensland took a different structural bet. By keeping Powerlink and CS Energy in public hands, the state government can fold some transmission cost into budget decisions rather than running it entirely through consumer tariffs, which is part of why Queensland’s energy plan rests on two pillars and one cliff face. It doesn’t make the cost disappear. It changes who absorbs the timing risk, and it means a Queensland household’s exposure to transmission blowouts runs partly through state finances rather than directly through the power bill. Different consumers, different states, genuinely different cost pathways for what’s supposedly one national project.
Where VNI West breaks the “benefits flow evenly” theory #
The clearest test case sits in a paddock dispute that’s dragged on for longer than anyone in Melbourne or Sydney planning offices would like to admit. VNI West, the interconnector meant to link Victorian and NSW renewable zones, has become a genuine flashpoint precisely because the cost-benefit split doesn’t match the geography. I covered the mechanics of that fight in VNI West: the interconnector stuck in a paddock dispute, but the short version for this piece is that landholders along the route carry amenity and land-use costs that never show up on anyone’s network tariff, while the consumers who benefit from improved interconnection are sitting in postcodes nowhere near the towers.
That’s not a hypothetical equity problem. It’s the actual mechanism. Transmission routing decisions get made on engineering and cost-efficiency grounds, which is defensible, but the compensation and consultation frameworks sitting underneath those decisions were not built for the scale or pace of the current build. Farmers along the Kerang corridor are not shareholders in the benefit. They’re hosts to the infrastructure that delivers the benefit elsewhere.
The capital markets angle nobody likes to say out loud #
Follow where the actual capital comes from and the picture sharpens further. Transmission businesses raise debt and equity against the regulated return the AER allows them. That return has to be attractive enough to pull in the capital at the volumes required. We’re talking a multiple of historical transmission investment levels, compressed into a much shorter window than the grid has ever attempted before.
Attractive enough for capital markets means a rate of return that, baked into decades of network charges, is not small. The AER’s own regulatory determinations process exists precisely to stop network businesses gold-plating this return, and it’s generally done that job reasonably well over the past decade. But the scale problem is new. When the asset base roughly doubles in a compressed period, even a disciplined allowed return generates a much larger absolute dollar flow out of consumer bills than the same percentage did against a smaller base. The mechanism hasn’t changed. The scale has, and scale changes outcomes even when every individual decision along the way looks reasonable.
This is the bit that gets lost whenever a minister stands up at a sod-turning ceremony and talks about nation-building infrastructure. Nation-building, sure. But it’s financed the way a toll road is financed: recovered from the people who use the asset, over a long horizon, with a return built in for whoever supplied the capital. Calling it a shared national investment obscures that it’s actually a very traditional piece of regulated infrastructure finance, just operating at a scale the regulatory architecture has never had to handle before.
What the Capacity Investment Scheme does and doesn’t fix #
The federal government’s response to generation investment risk has been the Capacity Investment Scheme, underwriting revenue for new renewable and storage capacity so projects can get financed despite wholesale price volatility. It’s a reasonable tool for de-risking generation, and I’ve gone through how the Capacity Investment Scheme actually works in detail elsewhere on this site.
But the CIS underwrites generation revenue. It does nothing for transmission cost recovery. That gap matters because generation and transmission are meant to arrive roughly together: a wind farm in a REZ is only worth building once the wires to export its output exist. When transmission slips, as it regularly has across the REZ programme, the underwritten generation sits there with capacity it can’t fully use, and the transmission cost still accrues on schedule regardless. Two different funding mechanisms, two different timelines, and consumers exposed to both sets of risk simultaneously without a mechanism that reconciles them.
The contrarian bit: efficiency and fairness are not the same test #
Here’s my actual disagreement with how this debate usually runs. Most criticism of transmission cost allocation focuses on whether the AER is letting network businesses earn too much. I think that’s mostly the wrong question now. The AER’s return settings have been reasonably disciplined post-2018 reforms, and treating every cost blowout as a regulatory capture story misreads what’s happening.
The real problem is that “efficient” cost allocation and “fair” cost allocation have quietly become different things, and nobody in the regulatory architecture is explicitly deciding which one governs. Efficient says: build the line where the engineering and connection economics are best, recover the cost from whoever’s in the relevant network tariff zone, let the market sort the rest. Fair would ask whether a Kerang landholder or a Hunter Valley household facing both REZ transmission costs and firming costs for an early coal exit should carry proportionately more of the national transition bill than someone in a state that timed its closures more conservatively. Efficiency is winning that argument by default, because nobody with the authority to change it has been asked to choose.
That’s not a scandal. It’s a structural gap, and it’s the kind of gap that regulatory reviews tend to find a decade after the cost has already landed somewhere nobody intended. The AEMC has levers here: jurisdictional derogations, revised cost-allocation methodologies, a harder look at how REZ access charges get distributed between generators and consumers, but none of that moves quickly, and the build-out isn’t waiting.
Where this actually lands #
Ask an energy minister who pays for transmission and you’ll get “the nation benefits, so the nation pays.” Ask an AER determination and you get a very different, much more specific answer: a named network business, a named jurisdiction, a named set of consumers on a named tariff schedule, over a named number of years. Those two answers are not reconcilable, and the gap between them is exactly where the political argument over the transition’s fairness is going to keep getting louder.
My read, for what it’s worth, is that the states carrying the fastest coal exits alongside the slowest transmission delivery are the ones who’ll feel this hardest, and NSW currently sits closer to that intersection than anyone in Macquarie Street seems comfortable admitting publicly. Whether that gets fixed through a cost-allocation rule change or through sheer political pressure once enough bills arrive is the open question for the next couple of regulatory cycles. Either way, somebody’s paying for every kilometre of line going up right now. The honest job of this desk is just to keep naming who.
– Marcus Wren, Editor
Image: Ché Lydia Xyang (CC BY-SA 3.0) via Wikimedia Commons