Option 2:
New Arrow Junction substation + double circuit line

Construct a new Arrow Junction substation, a 110kV double circuit line (following a similar route through the Kawarau Gorge area) from the Cromwell substation with an interconnection to the Frankton substation

This double circuit will be rated to approximately 2 x 180MW. This new line plus the existing line (rated 108/108MW) will increase the N-1 capacity to the Queenstown region from 108MW to 300MW. The Cromwell substation will be upgraded to support the new line and increase in capacity. Line length: approximately 36-38km.

Cost: approx. $134-$225 million

Estimated programme timeline: 5-7 years   

Pros Cons
  • Will support midpoint and maximum electricity growth to 2050 and beyond
  • Reliability and security increased with four circuits to Queenstown
  • Increase in cost vs increase in capacity provides good long-term value
  • Dual circuit line allows for lower risk upgrade to the existing 110kV line if needed in the future, if greater capacity is needed to support growth
  • Proposed to follow a similar route from Cromwell to reduce enabling works and construction cost
  • Easier access for materials and worker accommodation – close to Queenstown and Cromwell
  • Arrow Junction substation is in a good location to connect to the existing distribution network and take load off Frankton substation to unlock capacity for growth in the Queenstown CBD, Fernhill, Glenorchy, Frankton and Southern Corridor
  • Most popular amongst our experts. Highest scoring option against the option assessment criteria
  • Engineering will be required to mitigate fault line risk
  • More expensive than option 1, however provides big uplift in capacity, security and resilience for the additional cost compared to option 1
  • Not as resilient as option 4

More information

This option provides an uplift of approximately 190MW to Queenstown, which provides enough additional capacity for (at 110kV):

  • ~26,600 homes (5kW) 70%

  • ~760 small and medium businesses (25kW) 10% and 

  • ~152 larger commercial loads. (500kW) 20%

Estimated Cost to the Customer per year
Based on midpoint population growth scenario and current Electricity Pricing Methodology.

2032 - $360 to $610 per year

2050 - $270 to $450 per year

 

Option 1: New Arrow Junction substation + single circuit line
Option 3: New Arrow Junction substation (220kV capacity) + double circuit lines
Option 4: New Jacks Point substation + double circuit line