Option 3:
New Arrow Junction substation + double circuit lines (assets built to 220kV)

Construct a new Arrow Junction substation, a 110kV double circuit line (built at 220kV to allow for future growth beyond 2050, if needed) from the Cromwell substation (following a similar route through the Kawarau Gorge area)

This double circuit will be rated to approximately 2 x 180MW (2 x 360MW, if operated at 220kV). This new line plus the existing line (rated 108/108MW) will increase the N-1 capacity to the Queenstown region from 108MW to 300MW (480MW if operated at 220kV). The Cromwell substation will be upgraded to support the new line and increase in capacity. Line length: approximately 36-38km.

Cost: approx. $154-$255 million

Estimated programme timeline: 5-7 years

Pro Cons
  • Will support midpoint and maximum electricity growth to 2050 and beyond
  • Allows for uplift to 220kV operating voltage, which doubles the capacity of the line from 360MW to 720MW. Most future proof option
  • Will improve resilience with four circuits to Queenstown, N-3 if needed at 120MW
  • Increase in cost vs increase in capacity provides good long-term value, however, may never be needed
  • 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 Queenstown CBD, Fernhill, Glenorchy, Frankton and Southern Corridor.
  • 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
  • 220kV transmission towers are 10m to 20m taller, adding to more visual pollution. Footprint of towers are much larger too
  • Engineering will be required to mitigate fault line risk
  • More expensive than option 1 and 2, however provides a future-proofed option for $20-30M over option 2
  • With technology and changing energy usage, the 220kV may never be required, therefore unneeded capital expenditure
  • Slightly higher line maintenance cost with larger transmission towers
  • Not as resilient as option 4
  • Having both 220kV and 110kV voltages will make the interconnection between the new Arrow Junction substation and existing Frankton substation more challenging if 220kV is used in the future

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%

(at 220kV, which is 380MW)

  • ~53,200 homes (5kW) 70%

  • ~1,520 small and medium businesses (25kW) 10% and 

  • ~304 larger commercial loads. (500kW) 20%

Option 3: Estimated Cost to the Customer per year
Based on midpoint population growth scenario and current Electricity Pricing Methodology.

2032 - $415 to $690 per year

2050 - $310 to $510 per year

Option 1: New Arrow Junction substation + single circuit line
Option 2: New Arrow Junction substation + double circuit line
Option 4: New Jacks Point substation + double circuit line