Two 11,000 volt (11kV) submarine cables currently supply West Pittwater and Scotland Island residents and businesses. Ausgrid has been considering a broad range of options aimed at improving energy security to the area.
In 2018, Ausgrid discussed with the community the option to install a Microgrid system to provide a backup supply for long duration outages.
Since then, Ausgrid has undertaken extensive investigations into the feasibility of this option, including engaging with potential suppliers, reviewing detailed pricing estimates, construction methodologies and completing ecological studies. We have also looked at other network solutions.
This extensive feasibility investigation process has determined that:
- The cost of a Microgrid would be considerably higher than forecast;
- A behind the grid solar option would require full funding by residents, something residents told us via a survey they do not support;
- A Microgrid option would have also required significant clearing of trees and vegetation to ensure bushfire safety clearances for the site.
Additionally, with recent advancements in cable technology and construction methods, this process has determined a submarine cable is a more cost-effective and low maintenance solution for West Pittwater and our broader customers.
Ausgrid has already engaged with suppliers to prepare detailed scope and cost estimates for the installation of a submarine cable and cost estimates for the installation of a submarine cable between Catherine Park, Scotland Island and Halls Wharf, West Pittwater that will provide a ring network for West Pittwater.
The new submarine cable will provide a more reliable electricity network for West Pittwater and will:
- Greatly reduce construction and maintenance costs;
- Significantly reduce the environmental footprint;
- Limit visual impacts.
After detailed environmental assessment approvals are completed, Ausgrid is planning to install the submarine cable in mid-2021.
The new 11kV submarine cable will run underwater between Catherine Park, Scotland Island and Halls Wharf, West Pittwater – exact entry and exit points to be investigated during the environmental assessment phase.
This option links the existing 11kV networks at Scotland Island and West Pittwater with a new 11kV cable. By installing a cable, connecting these sites, we will create a ‘ring’ on the local network which will provide more options for restoring power in the event of an outage.
To minimise the impact to the sea grass beds at either end and to make sure that the cable is not snagged by anchoring and private moorings, it is proposed that the entry points will be underbored from each shoreline to about 150 metres into Pittwater.
This will be a much smaller scale project to the recently constructed Scotland Island work and would be completed in two sections. A drilling rig would be set up in Catherine Park and near Halls Wharf for about two weeks each, weather and ground conditions permitting.
The cable will be barged to site and then be installed through the entry/exit points and laid about 1.5 metres under the sea grass bed.
Construction is anticipated to start in mid-2021.
Benefits include:
- Significantly reduced cost when compared to the Microgrid’s initial installation cost;
- No ongoing maintenance costs and a significantly reduced whole of life cost;
- Significantly reduced environmental footprint and visual amenity.
