The Minister’s recent Talking Point (The Mercury 29th June) and attached as a screen shot below, attempts to recast Project Marinus as a source of “flexibility”, “resilience” and “capability”. These are worthy aspirations, but they bear little resemblance to the rationale on which Marinus was originally justified. For years, the Government promoted Marinus as an export project: Hydro would earn more by selling into the mainland market, Tasmania would capture higher prices, and the State would receive a $470 million annual “Marinus dividend”. None of these claims appear in the Minister’s article. There is a reason for that. Hydro is always settled at the Tasmanian price. It never receives the Victorian price, never receives the price spread, and receives no residues unless it buys settlement residue units at auction. Treasury confirmed the Whole‑of‑State Business Case (WoSBC) assumed zero inter‑regional revenue for Hydro. The Minister does not dispute this. Hydro’s projected profit uplift is not based on arbitrage, export revenue, residues or Marinus. It is based on Tasmanian prices rising as Tasmanian and Victorian prices converge. That is the only mechanism left standing.
The Minister also asserts that a 440‑megawatt data‑centre load “does not undermine the business case for Marinus”. This is simply incorrect. A 440‑megawatt continuous load is roughly 35 per cent of Tasmania’s average operational demand. It consumes the entire exportable surplus, forces Tasmania into net‑importer status, eliminates Hydro’s export optionality and collapses the assumptions underpinning the WoSBC. None of this was modelled. The WoSBC did not include a Tasmanian demand forecast. Treasury did not model demand. Hydro did not provide demand modelling. TasNetworks did not model demand. The Government has never published a long‑term Tasmanian demand forecast. The Minister’s Talking Point does not address this omission.
He goes on to claim that Marinus will “unlock new renewable generation”. But the WoSBC simply assumed new wind would be built without explaining who would fund it, who would underwrite it, how Hydro would finance power purchase agreements (PPAs), how many megawatts or gigawatt‑hours are required, how new renewables interact with Firmus, or how new renewables affect Tasmanian prices.
He also recasts “long‑duration, deep‑storage hydropower” as Tasmania’s strategic advantage. But the WoSBC did not model the impact of two‑hour, four‑hour and eight‑hour batteries, which are rapidly eroding the market value of long‑duration storage. Nor did it model the impact of Tasmania becoming a net importer, which further reduces Hydro’s ability to time storage and exports. Again, the Minister does not address this.
Perhaps the most striking claim is that Marinus and new industrial load “are not competing ideas”. They are. Marinus requires exports. Firmus eliminates exports. Marinus requires new renewables. Firmus requires new renewables. Hydro cannot underwrite new renewables. Tasmania is likely to remain a net importer. Marinus becomes an predominantly import cable. Hydro’s profit surge collapses. These are structural contradictions, not complementary outcomes as suggested.
The Minister concludes by saying Marinus “continues to stack up”. But the WoSBC is now obsolete. It did not model Firmus, any large new load, battery penetration, exportable surplus, price convergence, Hydro’s profit mechanism, new renewable funding or Tasmania becoming a net importer. The Minister does not say whether the business case has been recalculated. He does not say whether the exportable surplus has been recalculated. He does not say whether the cost‑benefit analysis has been recalculated.
Tasmania’s renewable future is not constrained by engineering or geography. It is constrained by economics. Woolnorth Wind Farm (WWF)’s accounts show wind is unviable without subsidies. Hydro cannot underwrite new wind and no funding exists. The Minister offers aspiration, not modelling.
And now a new factor has emerged. The sudden appearance of 440‑megawatt‑scale data‑centre proposals has thrown an entirely new variable into the equation – one that further undermines the already‑fragile business case for Marinus. It compounds the problem. How is renewable generation required for these data centres, plus that assumed in the Marinus modelling to be funded, built and integrated into a system that is already stretched. And how will Hydro deliver the massive profit uplift the Government’s Budget strategy depends upon when the very energy the business case had pencilled in for export may instead be consumed on‑island, some at government subsidised prices. Tasmania is now facing a future where demand growth, new industrial loads and unfunded renewable commitments collide directly with the assumptions underpinning Marinus and the Budget – and none of it has been modelled.
A more realistic reading of the Minister’s language is that Marinus is increasingly being repositioned as a Basslink replacement – a regulated interconnector used predominantly to import electricity when Tasmania is short of energy. That is what “flexibility, resilience and capability” now means in practice. Once large new loads such as Firmus consume the exportable surplus, Tasmania becomes a net importer, Hydro loses export optionality, and Marinus ceases to be an export project at all. And Tasmanians are entitled to feel misled. We were sold the Battery of the Nation story because it appealed to our sense of pride – a vision of Tasmania powering the mainland – while the fine print was quietly obscured, and whatever remained visible after the black marker pen had finished told a very different story. The rhetoric has changed, but the underlying reality has not: Marinus is drifting toward an import‑reliability role, not the export‑driven future the original business case promised.
It has become an expensive insurance policy that requires an open and honest appraisal and real consideration of the costs to Tasmanians and the alternatives to protect Tasmania’s interests.