by Rachel Williamson, Renew Economy
The full cost of the Marinus link subsea cable is now estimated to be $4.8 billion, according to the Australia Energy Regulator (AER), highlighting yet another major transmission project that is likely to run well over initial and even recent cost estimates.
The AER’s latest estimate for the so-called ‘Battery of the Nation’ is part of its assessment of what a fair price will be for Marinus Link Pty Ltd (MLPL) to pay – and therefore be able to charge users once it’s built.
The higher estimate is based on the extra $950 million that is needed for the North West Transmission Development, the TasNetworks-owned part of the project which is essential to connect the subsea cable to the Tasmania grid.
The AER’s current vision of what the subsea cable project will cost is almost $800 million more than what MLPL expected in its June 2024 RIT-T update.
And they could go even higher.
A newly released AER issues paper points out that only 46 per cent of MLPL’s own costs are settled – those relating to signed contracts for the undersea cable and installation, and converter station equipment.
The rest is still up in the air as the contractor set to deliver the balance of works isn’t due to be named until the end of this year.
The December estimate of MLPL’s own costs is still $3.9 billion, the company confirmed to Renew Economy.
Read the full story here: Bill for single cable Marinus Link now estimated at almost $5 billion.
Statement – Australian Energy Regulator (AER), 21 March 2025
AER consults on Marinus Link construction costs proposal
The Australian Energy Regulator (AER) has today released an Issues Paper in respect of Marinus Link Pty Ltd (MLPL) Stage 1, Part B (construction costs) proposal.
The Issues Paper sets out our initial observations on the proposed construction costs and the procurement process to date. This includes a proposed total construction expenditure of $3,534.3 million ($2023) for stage 1 of Marinus Link.
The Issues Paper also highlights key aspects of the proposal that we are particularly interested to hear from stakeholders to inform our initial draft decision.
We expect to release an initial draft decision in May 2025 on the market tested costs for converter station designs and the high voltage direct current cable system. This is approximately 46% of the total proposed capital expenditure for stage 1 of Marinus Link.
The AER expects a revised proposal from MLPL in July 2025, which includes updated costings on the remaining costs on the balance of works, support activities and risk allowance which are not assessed at the initial draft decision stage. A final decision which combines our assessment of each stage of the decision making process will be published in December 2025.
Concurrent to our ongoing assessment of Marinus Link, we have also released our determination on TasNetworks’ contingent project application for its North West Transmission Development stage 1 early works. Marinus Link and the North West Transmission Development together comprise ‘Project Marinus’.
Invitation for submissions
Interested stakeholders are invited to send submissions to inform our initial draft decision on the construction costs proposal by 18 April 2025. Submissions and requests to make a submission via alternative methods should be sent to [email protected].
Public forum
On Thursday, 3 April 2025 at 10:30am (AEDT) we will hold a public forum on Marinus Link’s proposal, the AER’s determination process and highlight key areas of focus within our Issues Paper. You can register your interest on Eventbrite here.
Background
On 29 November 2024, the AER received the construction costs proposal from MLPL for the proposed capital expenditure for the first Marinus Link cable over the 2025-2030 regulatory period.
Marinus Link is a component of ‘Project Marinus’, a single actionable project under AEMO’s 2024 Integrated System Plan. Stage 1 of Project Marinus will deliver a 750 MW interconnector (Marinus Link) between Victoria and Tasmania and associated network upgrades under the North West Transmission Development.
The AER’s assessment will focus on the efficiency and prudency of the forecast construction costs in accordance with the National Electricity Law and National Electricity Rules.
On 3 December 2024, the AER published an updated Commencement and Process Paper setting out a modified process for making a determination on the total construction costs. This includes a two-stage approach with an initial draft decision limited to the converter station equipment design and equipment costs and the high voltage direct cable system costs, with the remaining cost elements assessed in a supplementary draft decision.
Media release – Dean Winter MP, Labor Leader, 25 March 2025
Premier’s privatisation plans add to North West Transmission Development uncertainty
The North West Transmission Development has been on the drawing board for five years but still has no finalised route, no agreement with landowners, and no final costing.
With Jeremy Rockliff’s new plan to privatise TasNetworks in a desperate move to fix his budget mess, there are serious questions about the future of the project.
In 2023, the Liberals cut Northwest Transmission in half, and projects like Robbins Island, HIF e-fuels plant and Whaleback Ridge were left off the map with no plan to actually connect them to the network. 18 months later, there is still no plan to connect them and none of those projects can get started until they have certainty that they will actually be connected.
The Liberals even left stage 2 from its statement of expectations for TasNetworks.
Given what happened with the ferries fiasco, none of these proponents are going to want to invest unless there is a plan for their transmission to be constructed before their project is complete. They don’t want to be the ferry waiting for a berth.
Tasmania can’t afford to miss out on billions in economic activity and thousands of local jobs. The North West Transmission Development needs certainty, which is impossible for TasNetworks to provide with a potential sale or lease hanging over its head.
Media release – Clean Energy Tasmania, 25 March 2025
Government must end uncertainty over NW transmission
Clean Energy Tasmania is the voice of the renewable energy sector in Tasmania and is calling on the Tasmanian Government to end the uncertainty over the vital North West Transmission line project.
“The north west should be the renewable energy powerhouse of the state, but without the right transmission infrastructure all that is at risk,” Clean Energy Tasmania Chair, Ian Jones, said.
“The Tasmanian Government needs to outline a clear plan for how it is going to deliver the transmission lines, and the certainty, that the renewable energy sector needs on the north west.
“The Tasmanian Government likes to talk the talk when it comes to renewable energy, but now it’s time they walk the walk.”
Media release – Nick Duigan, Minister for Energy and Renewables, 25 March 2025
Power bills to skyrocket under Labor
Power bills are set to soar under Labor, after the opposition confirmed they will build the North West Transmission Line in its entirety, immediately.
Minister for Energy and Renewables, Nick Duigan, said unlike Labor who seem to be willing to write a blank taxpayers cheque, the Tasmanian Government is taking a commonsense approach.
“We’ve been clear – what needs to be built, will be built – in a careful and considered way,” Minister Duigan said.
“If their plan to maximise GBE profits wasn’t enough, they will also send power prices soaring – adding to the multitude of fees and charges they are planning to jack up to manage the budget.
“It is reckless for the Opposition to greenlight a $1.5 billion project without fully understanding whether its in Tasmania’s best interests.
“The Tasmanian Government continues to work with TasNetworks to progress the first stage ahead of a Final Investment Decision – just as is being done for Marinus Link.
“We will always act in Tasmania’s best interest and ensure Tasmanians continue to have the lowest possible power prices, while enabling economic growth and job creation. ”
Statement – SOLVE (Supporting Our Loongana Valley Environment), 25 March 2025
Halt Marinus and NWTD Projects
The north-west community group, SOLVE (Supporting Our Loongana Valley Environment), again condemn Project Marinus, again call for a halt to the NWTD, again call for TasNetworks to be sacked as Jurisdictional Planners of the Energy Sector, and again call for Tasmania’s two major parties to begin listening to community and independent energy sector experts.
It’s critical to note that this latest and biggest cost overrun doesn’t even include or refer to the massive costs that TasNetworks, backed by the state government and Labor Opposition, seek to impose on landholders, communities and small businesses across the north-west.
Worse again, it doesn’t include the horrific environmental costs to north-west habitat-rich forests, which will be bulldozed for the transmission line, including through the Loongana Valley and Leven River catchment, an area of critical biodiversity that includes dozens of threatened and endangered species.
For over six years our community has been pointing out the massive conflict of interest in having a corporatised state-owned company like TasNetworks determine what will give the greatest returns to itself and to corporate investors and its own sole shareholder, the state government, rather than serve the interests of Tasmanians.
We’ve called out the conflicted role TasHydro now has as an arbitrage speculator on the NEM, backing attempts to lure global energy investors with highly favourable (to investors) PPA’s.
We’ve pointed out that the claims of ‘jobs and growth’ are completely without substance, and that the ‘Battery of the Nation’ is just PR which serves the market, not ordinary Tasmanians.
We’ve called for fair and equitable energy-transition planning by communities, for communities, but at every stage we and other communities have been ignored, derided, had critical information withheld, and been lied to by TasNetworks.
It’s long past time the Liberal-Labor machine began to stop working for themselves and corporate investors. We need an energy transition that is cost-effective, can be staged, suited to every niche, and that doesn’t worsen environmental damage, increase fire risks, reduce biodiversity or trash the myriads of small tourism operators who are dependent on healthy wild forests.
We need energy production, distribution and storage to be returned to the public sector as a public utility, minus the egregious and corrupt planning and profiteering that serves the corporate sector.
We, the people, simply cannot afford what TasNetworks, the major parties and Project Marinus are demanding from us. Stop this environmental and economic vandalism now.
