Today marks an historic threshold in Tasmania’s energy story. From 1 July 2026, Basslink – for two decades an unregulated private interconnector – becomes a fully regulated transmission asset controlled by the Australian Energy Market Operator (AEMO).
This is a significant changes and it changes everything about how electricity flows between Tasmania and Victoria. And it gives Tasmanians their first real glimpse of how Marinus Link will operate.
For twenty years, Hydro Tasmania did not own Basslink, but it effectively operated it. Hydro determined when to export and when to import, and it captured the financial benefits of interstate trading. That era is over. That arrangement ended at the end of 2025 as APA took over ownership and control after the Basslink Services Agreement expired on 1 July 2026. During the most recent financial year, all revenues flowed to APA and owner and operator of Basslink as a Market Network Service Provider or merchant link.
From today, ownership remains with APA, who, under the new Transmission Network Service Provider recovers the costs of operating and maintaining the interconnector through the regulated revenue determined by the Australian Energy Regulator. What also changes is the control of the interconnector that shifts entirely to AEMO.
Hydro will participate in the National Electricity Market (NEM) like any other generator – submitting offers of quantities and minimum prices, stacked from lowest to highest. AEMO will then dispatch the cheapest available generation to meet demand across the NEM. If Basslink is unconstrained, AEMO decides whether Hydro’s offers are accepted and whether electricity flows north or south.
Hydro will not nominate “exports.” It will simply offer generation. AEMO determines where it goes.
It is worth noting that in 2025-26, when APA operated Basslink as an unregulated link, Hydro repeatedly complained that APA constrained flows and limited exports. But even if Hydro had exported more, it would still have received only the Tasmanian wholesale price – because that is how the NEM works. Hydro never receives the Victorian price or the price spread. That point has been consistently misunderstood in public debate.
Under the regulated model, Basslink’s owner no longer earns money from trading electricity between Tasmania and Victoria. Instead, it receives a fixed revenue allowance set by the Australian Energy Regulator. This amount is recovered through transmission charges paid by market participants and ultimately passed through to Tasmanian consumers via TasNetworks. The recently announced increases in Tasmanian retail electricity prices from 1st July reflect these increased charges.
When electricity flows between regions at different prices, the market generates inter‑regional settlement residues. AEMO nets positive and negative residues together into two pools – a northward and a southward pool. The pools are then auctioned, and the auction proceeds paid to the transmission providers. TasNetworks will use its share of proceeds to reduce the amount it needs to recover from Tasmanian consumers in the future. But at this stage we do not know how large these amounts will be because the Whole‑of‑State Business Case never modelled them.
The crucial point is that the regulated fee is now the main mechanism, and consumers carry that cost. The residue auctions provide only a variable, uncertain offset – and none of this revenue goes directly to Hydro.
This matters enormously for the Marinus Link debate. Marinus will operate exactly the same way as the newly regulated Basslink, albeit with greater capacity. The transition on 1 July is, in effect, a live demonstration of Tasmania’s energy future.
The Whole of State Business Case for Marinus was built on an assumption that Tasmania would remain a net exporter of electricity. But Tasmania’s energy landscape is changing rapidly. Large new industrial loads – including proposed 440 MW data centres – would consume Tasmania’s exportable surplus and push the state into net importer status. The WoSBC never modelled these loads. There is a stated expectation that new load will bring on new renewable generation to support it but no plan or strategy to achieve this.
In the scenario of significant additional load, Basslink and Marinus may well not function as export cables. They will need to function as import cables – bringing electricity into Tasmania when local generation falls short.
The Government’s language has already shifted to reflect this reality. “Flexibility,” “resilience,” and “capability” are now the preferred descriptors for Marinus. These are not export concepts. They are import concepts. When the Minister talks about flexibility and resilience, he is describing a cable that keeps the lights on when Tasmania is short and we are unable to generate enough on island.
Right now, Tasmania’s hydro storages are in a strong position – among the best at this time of year in recent decades. That is genuinely good news for energy security in the near term.
But the critical question is not today’s storage level. It is tomorrow’s demand. A shift to El Niño conditions – which climate patterns suggest is possible and are likely to lead to an extended dry period – typically brings lower inflows, drier catchments, and greater volatility. Add 440 MW of new industrial load to that picture, and the pressure on storages becomes significant precisely when inflows may weaken.
Today is a milestone, but it is also a moment of clarity. For the first time, Tasmanians will see how a regulated interconnector actually operates – without Hydro controlling the gate, without the illusion of a private export highway.
The original “Battery of the Nation” narrative was always more aspiration than analysis. Today we begin to see what the regulated interconnector model actually delivers – and what questions the Government still has not answered about Marinus.
I will continue to scrutinise this project on behalf of Murchison constituents and all Tasmanians who deserve a transparent, evidence-based account of what Marinus is, what it costs, and who bears the risk.
Below is a Q&A summary of the key issues:
1 JULY 2026: BASSLINK BECOMES A REGULATED INTERCONNECTOR
Q: What exactly happens on 1 July 2026?
Basslink stops being an unregulated private interconnector and becomes a fully regulated transmission asset. Control of flows shifts from the private owner (APA) to the Australian Energy Market Operator (AEMO).
Q: Why is this change significant?
For the first 20 years of Basslink’s life, Hydro effectively operated the link. It decided when to export and when to import, and it received the financial benefits of interstate trading. From 1 July, Hydro loses that operational control entirely.
Q: Didn’t Hydro own Basslink?
No. Hydro never owned Basslink. But under the original arrangements, Hydro controlled its operation and captured the trading benefits. That era is over.
Q: What happened after APA took over Basslink?
In 2025–26, APA operated Basslink as an unregulated link. Hydro complained APA constrained flows and limited exports. But even if Hydro had exported more, it would still have received only the Tasmanian price – because that is how the NEM works. Hydro could export more or export less – it still only ever received the Tasmanian price.
Q: What changes for Hydro on 1 July?
Hydro becomes just another generator in the NEM. It will submit offers – quantities of electricity and the minimum price it is willing to accept – and AEMO will decide whether those offers are dispatched. Hydro will not nominate “exports”. It will simply offer generation. AEMO determines whether that generation flows north or stays in Tasmania.
Q: How does bidding actually work?
Hydro, as do other generators, submits a stack of offers, from lowest to highest price. AEMO dispatches the cheapest available generation to meet demand across the NEM. If Basslink is unconstrained, AEMO decides whether Hydro’s offers clear into Victoria or remain in Tasmania.
Q: Why is 1 July an historic day for Tasmania?
Because it is the first time Tasmanians will see how a regulated interconnector actually works for Tasmania. This is the model Marinus Link will use. Basslink’s transition is effectively a live demonstration of Tasmania’s future under Marinus.
Q: What does this mean for Tasmania’s energy security?
It means Tasmania will rely on AEMO’s dispatch decisions, not Hydro’s operational discretion. If Tasmania becomes short of energy – for example, due to large new industrial loads – Basslink will operate as an import cable.
Q: How does this relate to the proposed 400 MW data centres?
A 440 MW load would consume much of Tasmania’s exportable surplus and push the state into net‑importer status. In that scenario, Basslink and Marinus become import cables, not export cables.
Q: Does this undermine the original Marinus business case?
Yes. The WoSBC assumed Tasmania would remain a net exporter. It never modelled large new loads like Firmus. Once Tasmania becomes a net importer, Marinus is no longer an export project – it is an expensive insurance policy.
Q: What is the political significance of 1 July?
Hydro’s privileged control over Basslink disappears. The public will see, for the first time, how interconnection really works – and how much of the original Marinus narrative survives contact with reality.
Q: What should Tasmanians expect next?
AEMO‑controlled flows, transparent dispatch, and a clearer picture of Tasmania’s true energy position. If demand rises sharply, Tasmania will import more. If new renewables fail to materialise, Tasmania will import more. Marinus will operate the same way.
Q: Do we have enough water in storage to meet rising demand?
Right now, yes. Tasmania has never had as much water in storage at this time of year as it did in the carbon‑tax years of 2012 and 2013, when storages were at record highs and Hydro then posted some of its strongest underlying profits. Current storage levels give Hydro a strong starting position.
But there is an important caveat. Hydro’s storages are high – but an El Niño looms on the horizon. A shift to El Niño conditions typically brings lower inflows, drier catchments, and greater volatility. Large new industrial loads – including proposed 440 MW data centres – would increase pressure on storages precisely when inflows may weaken. The question is no longer whether Hydro has enough water today, but whether Tasmania has enough water once demand rises and inflows fall at the same time. The issue isn’t today’s storage level – it’s tomorrow’s demand.