Marinus Link: supercharged renewable enabler?

While Australian states have varying renewable ambitions, Tasmania has swept the board with 100% renewable status and a target of 200% renewables by 2040.*

Tasmania boasts highly productive wind farms, abundant hydro-electricity and deep energy storage. The Marinus Link, when complete, aims to connect the mainland electricity sysyem to these resources, so states in the National Electricity Market (NEM) can benefit from a reliable supply of cheap, clean energy.

Detractors say the proposed $3.5 billion,1500MW undersea and underground pipeline – linking Tasmania’s north-west coast and Victoria’s Latrobe Valley – could become obsolete, as more and cheaper big battery projects drive costs down.

The current state of play

The proposed interconnector is Tasmania’s second pipeline sending clean energy to and from the mainland (the first being the 500MW Basslink). Designed as two 750MW projects, delivered two years apart, the project would also unlock - stored excess energy in a proposed deep, long-duration hydro battery.

Despite priority status and fast tracking by the Morrison Government, the pandemic has pushed completion back to late 2024, a year longer than anticipated. Marinus Link CEO Bess Clark still points to a ‘very favourable’ outlook, and a forecast of more than $4 billion in net benefits.

With Basslink now running at full capacity, Marinus Link could quadruple the amount of electricity travelling between Burnie and Gippsland.*

Filling the gap left by coal

Marinus Link will help Australia transition from coal-fired power to clean energy, Ms Clark said. It’s also uniquely placed to draw on world-class wind power – generated in Tasmania – as well as abundant solar and wind energy from Victoria.*

Marinus Link’s two-way system offers this flexibility, she said.
“We can draw energy from where it’s most plentiful, then move or store it as needed. While we expect to send most energy north, to Victoria and NSW, it can also support Tasmanian load.

“Marinus can fill the gap left by rapidly retiring coal generators in the Latrobe Valley, and across the mainland. Using cost-effective pumped hydro as a deep battery, we greatly increase our dispatchable capacity.”

Marinus Link engineers are also working on innovative converter technology, capable of starting the power system in a blackout.

The question of costs: will it pay?

Not everyone sees Marinus Link as part of the solution. Energy analyst Marc White poses two key questions about the interconnector’s viability.*

1. Could wind power make electricity bills more volatile, due to its variable nature?
2. Will Tasmanians bear the brunt of the costs, while other states enjoy the benefits

On the first point, Bess Clark argues that Victorian solar energy can be sourced when the wind doesn’t blow, and vice versa. Hydro generation and pumped hydro storage can also be drawn down on demand.

Secondly, she said work is underway to update cost allocation frameworks. 'We haven’t achieved formal consensus yet, but there is recognition the cost allocation model needs to change. The national energy cabinet is considering a change to national electricity rules, and TasNetworks is also progressing analysis.”

Big batteries or deep storage?

According to energy market expert Dr Bruce Mountain, Marinus Link could become obsolete as cheaper big battery projects come online.*

Published by the Victoria Energy Policy Centre, 2021 research concludes it is more effective to build large-scale battery projects on the mainland – particularly in Victoria – rather than transporting power from Tasmania.

The cost of building a 1,500MW big battery, with up to four hours of storage, could provide backup power 20% more cheaply than Marinus Link estimates.

Bess Clark agrees that batteries will inevitably become more inexpensive. Alone, however, they are unlikely to cover the huge gap left by retiring coal, she said.

'We also need energy to put into the batteries, and Tasmania has some of the cheapest clean energy resources in the world, especially in terms of wind. Pumped hydro offers days of storage, covering still and cloudy times. AEMO agrees the future lies in deep storage, and Marinus Link takes full advantage of this.'

Different forms of energy storage are important elements in an expanding renewable framework. Marinus Link, while not the complete solution, looks set to play a prominent role in our clean energy transition.

Sources:
*https://www.premier.tas.gov.au/site_resources_2015/additional_releases/tasmania_is_the_envy_of_the_world_in_renewable_energy
*https://www.theguardian.com/environment/2020/jun/19/marinus-link-could-send-clean-energy-across-bass-strait-but-its-future-is-uncertain
*https://www.hydro.com.au/docs/default-source/clean-energy/our-power-stations/power-of-nature.pdf?sfvrsn=15c22528_2.
*https://www.abc.net.au/news/2021-01-06/foreign-investment-in-tasmanian-wind-farms-raising-concerns/13036164
*https://reneweconomy.com.au/big-batteries-will-render-marinus-link-obsolete-new-analysis-suggests/#:~:text=Mountain%20compared%20the%20cost%20of,than%2020%20per%20cent%20cheaper