Tasmania’s electricity grid runs on energy that is more than 90% renewable, harnessing the power of its rivers and lakes, using an expansive network of dams and turbines to generate clean, renewable hydro energy. This is further enriched by wind power, with wind farms on the coast fuelled by the ‘roaring forties’, the strong westerly winds that occur between the latitudes of 40° and 50° south.

Currently, the island’s 570,000 population has limited connections to the Australian mainland. However, an ambitious new project, the Marinus Link, is proposed to provide an underground and subsea 1.5 GW transmission line and data connector between Tasmania and mainland Victoria (6.5 million population). The project could be delivered in two stages, each of 750 MW capacity, and transform the island into a significant clean energy exporter.

The project includes high voltage direct current (HVDC) cables, fibre optic cables, a communications station, and converter stations at each end. The link will connect a converter station at Heybridge, in Tasmania’s north-west to Waratah Bay, in Victoria. Once in Victoria, the cable will run underground about 90 km to a second converter station in Hazelwood. The project will be operated by Marinus Link Pty, which is jointly owned by the national Commonwealth, Victorian and Tasmanian state governments.

Construction of the first cable and associated infrastructure should begin in 2026, subject to a financial investment decision. Followed by the second stage from 2030.

Stage 1 is estimated to cost A$3.86bn ($2.45bn). Equity funding from the Commonwealth, Tasmanian and Victorian government shareholders will cover 20% of costs – in a joint venture split 49% Commonwealth, 17.7% Tasmania and 33.3% Victoria ownership. The remaining 80% will be debt funded through a Clean Energy Finance Corporation established by the national government.

According to a spokesperson of Australia’s Department of Climate Change, Energy, the Environment and Water (DCCEEW): ‘The Marinus Link investment is estimated to deliver 1,400 additional jobs at peak construction during Stage 1; increasing to 1,600 during Stage 2.’ Stage 1 is expected to provide over A$1.4 bn ($885mn) of economic stimulus to Tasmania, during construction and operation. With Stage 2 expected to add a further A$2.1bn ($1.3 bn).’

Rise of renewables  
By accessing Tasmanian green energy, Victoria can continue its transition from coal and gas to renewables. For the first time, electricity generation from Australia’s solar and wind farms matched that of coal-fired power plants in 4Q2024. However, there is still significant reliance on coal. As of 1 April 2024, the prime fuel source for energy generation in Victoria was brown coal, with a generation capacity of 4.8 GW, followed by wind, gas turbine, hydro and grid solar, according to Statista.

Australian Energy Market Operator (AEMO), a public transmission agency, also reports a rise in rooftop solar output, while coal-fired generation contributed less than half of National Electricity Market (NEM) generation in 4Q2024.

‘Renewable energy supplied a record 46% of the market’s electricity, peaking at 75.6% for a period on 6 November, driving emissions to record low levels,’ said AEMO’s Executive General Manager, Reform Delivery, Violette Mouchaileh. This marks a significant shift in Australia’s energy mix, as renewable energy is on track to potentially surpass coal.

The DCCEEW said in a public statement: ‘Coal and gas accounted for around 70% of electricity generation in 2021.’ It added: ‘Over the last decade, the share of electricity generated by renewable energy in Australia has increased significantly, rising from around 10.5% in 2010 to 29% in 2021.’

‘Australia’s energy infrastructure is at a turning point. It needs to shift from an outdated coal-dominated system to a modern, renewable energy-friendly one.’ – Sydney-based energy consultancy Energy Action

Building momentum  
Marinus Link has secured agreements with Japanese-owned Hitachi Energy for the DC converter technology, with Milan-based Prysmian winning the tender for the cables. The operator is awaiting ‘a notice to proceed’ prior to making a final investment decision.

Whilst the Marinus Link spokesperson considers the project to be ‘nation-building’, there are critics who question the viability of the scheme.

Tim Buckley, Director at Sydney-based think tank Climate Energy Finance, supports the interconnector despite concerns about the link being ‘a geographically, geologically, and engineering-wise as well as financially challenged project’. In fact, Buckley supports having two links, in case a fault occurs at some point in one of these assets. ‘It’s deep water, it’s ocean, and of course, Mother Earth is a powerful force,’ he said.

Furthermore, although environmentalists voice concerns regarding the impact of dams and wind turbines on native flora and fauna, most seem to be supportive of the link. The Climate Council, for example, hopes the link will boost Australian renewable energy: ‘Building more transmission... will help make our grid more resilient... because more transmission means more options.’

The project will be bolstered by key transmission upgrades to Tasmania’s north-west electricity network, boosting links to renewable energy generators. It will offer an alternate path to the existing 500 GW interconnector Basslink, which connects the Loy Yang power station, Victoria, to the George Town substation in northern Tasmania. It is currently the only electricity interconnector between Tasmania and Victoria, so the new link offers increased energy security and reliability.

‘During the day Tasmania can build up energy storage over time using solar or wind power from Victoria and then supply hydro or wind power to Victoria during their longer renewable droughts,’ said a Marinus Link spokesperson.

‘The great thing about hydropower is that it’s always ready to go, even during extended periods without sun or wind, like in Victoria’s winter or at night.’ Unlike batteries, which would deplete over time, hydropower can sustain the supply, the spokesperson explained, delivering low-cost, reliable and clean energy to the NEM, a wholesale market through which generators and retailers trade electricity in Australia. This infrastructure underlines the national importance of the new link, given that the NEM spans the east coast of Australia, from south-east Queensland, through New South Wales (NSW), Victoria, South Australia and across the Bass Strait to Tasmania.

Each Australian state has its own grid, and they are linked – interconnectors also exist between Queensland and NSW, NSW and Victoria, and Victoria and South Australia.

Planning for construction is now in full swing for the Marinus Link. In January 2025, engineering and construction consortia TasVic Greenlink and Empower were selected by Marinus Link Pty as the final contenders for the initial 750 MW cable civil construction works package.

With momentum building behind the project, Marinus Link has submitted a development application to Burnie City Council for approval to build the Heybridge converter station and lay the cable beneath a railway line, a highway and the shore to reach the Bass Strait. Final approval for the project is expected mid-2025. However, estimating the project costs has proven challenging. The overall cost has risen 17% since plans were first laid, primarily due to ‘unprecedented demand’ for subsea cables in Europe, according to interim CEO Dr Collette Burke.

The winner of the Stage 1 civil construction tender is expected to be announced by this end of the year. The chosen consortium will also be responsible for all onshore civil and installation tasks.

A turning point  
The Marinus Link is one of a series of renewables-friendly projects in Australia, including the Australian Renewable Energy Hub (AREH) in Western Australia’s Pilbara region, which is developing up to 26 GW of wind and solar capacity, starting construction later this decade, according to Renew Economy.

Another project is the 436.5 MW Tarong West Wind Farm in Queensland’s South Burnett region, which is set to begin construction in 2025.

These ambitious projects need to be matched with the right infrastructure. According to Sydney-based energy consultancy Energy Action: ‘Australia’s energy infrastructure is at a turning point. It needs to shift from an outdated coal-dominated system to a modern, renewable energy-friendly one.’ Privately funded initiatives are also planned to support transmission from renewables-friendly locations in Australia to consumers abroad. For instance, Australia-based SunCable (owned by a consortium led by Grok Ventures) is planning to build a 4,300 km subsea transmission cable to carry solar power from Australia’s Northern Territory to Singapore.

• Further reading: ‘Power up: How Australia plans for massive Asia renewable energy hub’. Australia plans to establish one of the world’s largest renewable energy production hubs, capitalising on the vast solar and wind resources of the remote Pilbara region of Western Australia. This privately-funded initiative, led by BP, represents a significant step in the nation’s push towards renewable energy and its goal of achieving net zero emissions by 2050, encouraged by the country’s centre-left Labour government. 
• How is the Albanese government of Australia investing in the country’s solar industry to ‘supercharge’ its ambition to become a renewable energy superpower?