Undergrounding

Undergrounding

Using Underground Cables

The most appropriate way to minimise fire-risk and the damage to critical infrastructure would be using underground cables.  The Victorian Bushfires Royal Commission (post 2009) determined that electricity infrastructure was responsible for causing a significant number of serious bushfires.

Subsequently, the Victorian Government contributed $750 million to the Powerline Bushfire Safety Program to those areas in highest risk. Significant coordinated planning by (CFA, DELWP, FFMVic, infrastructure owners and other agencies) is now ongoing with activities underway to minimise the risk of bushfires from electrical infrastructure. With this knowledge in mind, it would be psychologically distressing to see such high-risk infrastructure forever in view, as a constant reminder of the fire risks, now significantly increased.

So far, AusNet and the AEMO have pushed the benefits of an overhead High Voltage Alternating Current (HVAC) solution, while they have dismissed other options like High Voltage Direct Current and undergrounding on the basis of technical feasibility, cost, and by saying that undergrounding is worse than overhead for the environment.

These generalisations are wrong, and they are misleading.

Murraylink

Image: NKT Murraylink, Australia

Case Study – Murraylink

The Murraylink interconnector is an Australian underground transmission project which is both technically and economically feasible. It ships power efficiently underground for 177 km between Redcliffs, Vic, and Berri in SA.

And in fact, this underground High Voltage DC cable won an Environmental Excellence award in 2002 for best practice and innovation in environmental management. It did not damage the environment as AusNet suggests. I have spoken with the project engineer for Murraylink and he told me that while there was initial ground disturbance to bury the cable, in the whole 177km they only removed one tree!

The Murraylink design used existing rights of way along roadsides to minimise the environmental impact, and only required an easement of 6m wide, not 60 – 100m for overhead. It used horizontal direct drilling to get the cable under sensitive heritage sites and environmentally significant areas, and roadways, rather than digging through them. It even drilled under the Murray River.

Marinus Link

Image: Marinus Link

Case Study – Marinus Link

To provide another example, the Marinus Link is a new project being proposed by AEMO for a second transmission link from Victoria to Tasmania. This is being proposed as an undersea High Voltage DC cable.

This is understandable, because you can’t use towers to get to Tasmania, but what is significant for us here in Moorabool is that the Victorian portion of the project, which is 90 km in total in Gippsland, from the beach to Hazelwood, is going to be an underground High Voltage DC cable.

For the Marinus Link, which is only 230 kms from here, on the other side of Melbourne, the business case determined it would be more cost effective and technically feasible to continue with DC and to put it underground, rather than going overhead.

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