Tasmanian Premier Jeremy Rockliff seeks ‘formal advice’ on Marinus Link tick-off, keeps power prices secret

The green dream of Tasmania becoming the renewables ‘battery of the nation’ continues to turn sour, with claims of ongoing suppression of projected power prices.

Artist's impression of the Marinus Link Undersea-HVDC cable before being buried beneath Bass Strait sea floor.

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Tasmania’s caretaker government is seeking “formal advice” on whether it can sign up to the state’s biggest modern infrastructure project without opposition blessing, despite experts suggesting it is not necessary.

Liberal Premier Jeremy Rockliff, struggling to cobble together crossbench support for a minority government after the election of a hung parliament, wants to proceed this week with the $5bn-plus Marinus Link.

Opposition Leader Dean Winter, who will try to form government if Mr Rockliff cannot, has refused to give Labor’s backing for the 345km cable between northern Tasmania and Victoria, and associated transmission lines.

Mr Winter has cited Mr Rockliff’s refusal to give Labor and the crossbench sufficient time and access to digest 1000 pages of documentation and to release the project’s whole-of-state business case.

In response, Mr Rockliff said he was seeking “formal advice to see if we can proceed” with the project, in which Tasmania would be a minority partner with the federal and Victorian governments.

“What is holding this up is Mr Winter, who has absolved himself of his responsibility in caretaker convention,” Mr Rockliff said.

However, several constitutional law experts told The Australian there was no legal requirement to obtain the opposition’s approval.

“Convention requires consultation on major decisions during the caretaker period – consultation does not require agreement,” said Anne Twomey, professor emerita of the University of Sydney. “The opposition has no veto.”

Donald Rothwell, professor of international law at the Australian National University’s College of Law, agreed, saying caretaker provisions were “practice and not law”.

An artist’s impression of the Marinus Link between Tasmania and the mainland.

Mr Winter accused Mr Rockliff of playing politics and betraying voters by refusing to release the whole-of-state business case despite promising to do so a month before any final decision.

“Under caretaker conventions, Jeremy Rockliff doesn’t need Labor’s endorsement – so what was the point of the last few days?” he said.

“He has had the final business case for two months. He promised the public would see it before any final decision was made – but now he’s refusing to release it until after he signs off on the deal.”

The Premier, whose handling of the project approval has angered some of the crossbench MPs whose support he is seeking to provide confidence and supply deals, said he would not release the business case until after the deal was signed on August 2.

His government has had the document since May 16 and promised then to release it “30 days” before any final investment decision. It shared the study with Labor and crossbench MPs for the first time in highly controlled, secret briefings on Tuesday.

The Premier blamed the backflip on the need “not to jeopardise” the deal.

Those briefed on the business case suggest it contains “ugly” projections on increased power prices, chiefly to pay for the $1.14bn transmission infrastructure required in northwest Tasmania.

Mr Rockliff would not reveal the extent of these projected price hikes but said prices would be “far worse” if the highly contentious project did not go ahead.

The Marinus Link.

He confirmed reports in The Australian that the business case estimated the state would gain up to $400m a year in extra revenue from exporting more power via the cable to the mainland.

He also confirmed The Australian’s reports that this extra income – which some of those briefed have described as being predicated on “flimsy” assumptions – would be used to negate power price hikes.

Asked if he could guarantee Tasmanians would not be worse off under Marinus, he replied: “Yes.”

Mr Rockliff said recent negotiations with the Albanese government had seen it agree to contribute to the northwest transmission project. Tasmania’s equity contribution would be capped at $103.5m, he said.

However, he did not answer clearly when asked how the project would add to state debt, which his government already plans to treble over three years to $13bn. “Well, this is a significant investment,” he said.

Tasmania does not currently have an overall surplus of power to export but the business case for the 750-megawatt Bass Strait cable is based on the project fuelling a “wind rush” and other on-island energy projects.