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By April Shepherd, Editor, Monkey Media

Marinus translates to marine in Latin, or ‘connected to the sea’ – which is exactly how the Marinus Link project plans to bring Tasmania’s abundance of renewable energy to Australia’s future electricity grid. The project’s proposed 1500MW underwater interconnector will provide the network of the future with ample storage and energy, straight from the pristine apple isle to the Latrobe Valley in Victoria.

As the National Electricity Market (NEM) begins its slow eradication of coal to be replaced by clean energy, the worries of storage, supply and possible shortages take centre stage.

One of the solutions to possible shortages is increasing storage capacity and availability of renewables; which are abundant in the island of Tasmania, known for its pristine environment and natural resources.

Marinus Link, a subsidiary of TasNetworks, is a proposed 1500MW capacity undersea and underground electricity interconnector, aiming to link Tasmania and Victoria as part of the country’s future energy grid; running from North West Tasmania to the Latrobe Valley in Victoria.

The 1500MW capacity can supply 1.5 million Australian homes with electricity at any given time, with the project aiming to unlock savings of at least 140 million tonnes of CO2 by 2050.

The project features approximately 255km of undersea High Voltage Direct Current (HVDC) cable and 90km of underground HVDC cable, and will be supported by transmission network developments in the North West Tasmanian electricity network.

Timeline: the progress so far

The project began in 2017 with the first phase, the Feasibility and Business Case Assessment, completed in late 2019. Three years since its inception, Marinus Link is currently progressing through the design and approvals phase, which involves cost analysis, deciding route options, and undertaking surveys of the local areas.

The next step is the construction phase, which will follow a final investment decision expected in late 2024. The top priorities of this stage include:

• Refining the route in consultation with landowners, traditional owners and communities
• Refining technical and power system design and specifications
• Completing land/sea survey works and environmental referrals
• Continuing important community and stakeholder engagement to build social licence and maximise benefits for the community
• Progressing revenue setting and pricing frameworks that ensure a fair cost allocation outcome

The construction phase is set to last four to six years, and once operational the interconnector will contribute to Australia’s National Electricity Network for around 40 years.

Like many other infrastructure projects across Australia, COVID-19 lockdowns and associated restrictions impacted the Marinus Link project’s ability to conduct surveys and other critical works over the past two years, particularly
in Victoria.

The Australian Energy Market Operator (AEMO) has acknowledged that several transmission projects experienced schedule adjustments due to COVID-19 and other factors, including supply chain issues stemming from the “long-running and accelerating global boom in infrastructure investment”.

AEMO: Marinus Link project a major priority

The AEMO discussed the challenges of transforming Australia’s energy network in its 2022 Integrated System Plan (ISP), and found that Marinus Link is a project to be prioritised. The 2022 ISP states that Marinus Link should be delivered as soon as possible to deliver clean energy for the national grid.

Marinus Link CEO, Bess Clark, said, “This report highlights that Marinus Link will unlock Tasmania’s incredible clean energy resources for the benefit of all Australians and play a critical role as we transition to cleaner energy at lowest cost.

“Australians from Hobart to Cairns, and right across the NEM, will be better off with Marinus Link.”

The ISP also recognises that Marinus Link will provide increased security and reliability for the national grid.

“With recent cold conditions along Australia’s east coast and other supply-chain challenges, Australian energy consumers have been faced with potential black-out conditions,” Ms Clark said.

“The construction of Marinus Link will enable the mainland to access Tasmania’s abundant renewable energy and deep storage, ensuring that we can help keep the lights on right across the country.”

Marinus Link is expected to create approximately 2,800 direct and indirect jobs in Tasmania and Victoria during its construction and operation, and attract $7.1 billion worth of additional economic activity.

The project will support the renewable energy industry, that in turn supports jobs well beyond the interconnector’s construction phase. The Marinus Link project aims to aid in Australia’s decarbonisation and allow for downward pressure on power prices across the NEM.

The Marinus Link interconnector will also provide ongoing jobs as it operates the power system, connects new customers, manages vegetation along the proposed route and conducts maintenance tasks that support a project of this magnitude.

Cost benefit analysis

Marinus Link has undergone a rigorous cost benefit analysis (CBA), taking into account multiple variables, assumptions and future scenarios.

In order to determine these costs and benefits, AEMO takes into account several principles and steps that must be undertaken as set out by the CBA guidelines published by the Australian Energy Regulator (AER). Total customer benefits are difficult to estimate precisely, especially as energy market policy settings continue to evolve.

However, the overall robustness of the net market benefits provided by the Marinus Link to the NEM, is substantiated with the publication of the Project Marinus Project Assessment Conclusions Report (PACR), which demonstrates that, despite the continual evolution of inputs and assumptions, the Marinus Link will provide  significant benefits to the NEM.

Keeping prices low, and energy abundant

From Cairns to Hobart, the Marinus Link plans to help deliver low-cost, reliable, secure, clean energy to millions of Australians across the NEM; by unlocking Tasmania’s abundant, low-cost wind resources and pumped hydro storage facilities.

Tasmania is in a unique situation where it already produces more renewable energy than is needed locally, so the Marinus Link will deliver the state’s surplus clean energy to the mainland to keep emissions down, increase grid reliability and ensure electricity affordability.

Like other interconnectors across the NEM, Marinus Link is largely about harnessing the increasing diversity of energy generation in Australia, which includes wind, solar and hydro energy sources.

Marinus Link will access the existing spare and refurbished dispatchable capacity in the Tasmanian hydro-electric system for the first stage of the link, and enable the development of long-duration pumped hydro facilities with the second stage of the link.

This will minimise market volatility, which suppresses energy price rises from more expensive solutions; reducing reliance on coal and peaking-gas alternatives.

Why not just build more batteries in Victoria?

Independent modelling by AEMO, CSIRO and Ernst and Young suggests the NEM will experience periods of minimal solar and wind generation. These periods typically last between 36 to 48 hours and are commonly referred to as ‘renewable droughts’, which occur at least three to four times a year.

This modelling suggests Tasmanian long duration energy storage would cost less than half the amount of equivalent battery storage technology on mainland Australia. The reason for the lower cost comes down to the longer depth of charge and longer asset life of a pumped hydro energy storage system compared to a battery energy storage system.

Cost-effective batteries are best suited for meeting the shorter duration super-peak demand (typically evening time) while long duration pumped hydro provides seasonal shifting of energy.Batteries and the Marinus Link can work together, in unison, to create a more sustainable NEM for Australia.

In fact, the majority of future power system studies highlight the complementary nature of short and long duration storage. Both are needed to operate the power system in a cost-effective, reliable and clean manner, and both will be required as part of Australia’s rapid energy transition.

Marinus Link modelling forecasts that more than 75 percent of new storage deployed will be battery technology, while the cost of batteries will reduce by up to 70 per cent in the next decade.

This modelling also shows that it would still cost at least twice as much for batteries to deliver the same storage benefits as pumped hydro, based on a shorter technical life requiring batteries to be replaced and a shallower depth of charge.

AEMO has also confirmed that even in a situation where there is significant uptake of battery storage, as much as 10,000MW of batteries, Marinus Link is still needed to support lowest cost customer outcomes.

This is because a portfolio of up to 19,000MW of varying storage technologies will be needed to manage grid reliability, stability and affordability as the energy market transitions over the coming decades.

Batteries are important as short-term responders by facilitating ‘day shifting’ of energy, which is storing excess solar energy throughout the day for use at night time.

Hydro storage offers both day-shifting and longer-term seasonal-shifting of energy (the storing of excess energy for longer periods of wind and solar droughts), which means stored energy can be dispatched for days on end.

As coal-fired generators continue to retire at an accelerating pace, additional interconnection will be needed to fill the gaps. Marinus Link aims to ensure that all customers across the NEM will have access to low-cost, clean and dispatchable energy to fill the gaps left by retiring fossil-fuel generators.

Engaging community perspectives

Marinus Link is prioritising protecting the environment throughout the project, working with local communities through ongoing land surveys, regular engagement and listening to community perspectives.

The Marinus Link team invites feedback from the community, which will continue to help inform project design, construction considerations, development of environmental, cultural heritage and social and economic impact assessments.

As the original proponent of the project, TasNetworks started engaging with key stakeholders and industry about Marinus Link back in 2018, with a focus on raising awareness about the project and supporting various studies into the project’s feasibility and business case.

In Victoria, Marinus Link established a Gippsland Stakeholder Liaison Group (GSLG), which provides a forum for regular face-to-face communication and engagement between the Marinus Link Project Team and key stakeholders from the Gippsland region.

Marinus Link’s ongoing work and engagement with communities across Tasmania and Victoria is a fundamental part of the project’s development.

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