Option 1:
New Arrow Junction substation + single circuit line
Construct a new Arrow Junction substation, a 110kV single circuit line from the Cromwell substation (following a similar route through the Kawarau Gorge area) with an interconnection to the Frankton substation.
This single circuit will be rated to approximately 180MW. This, paired with the existing 110kV dual circuit line rated to 108/108MW, will increase the N-1 capacity to the Queenstown region from 108MW to 240MW. The Cromwell substation will be upgraded to support the new line and increase in capacity.
Cost: approx. $122-$204 million
Estimated programme timeline: 5-7 years
| Pros | Cons |
|---|---|
|
Will support minimum and midpoint electricity growth to 2050 Reliability and security is increased slightly with three circuits to Queenstown This is the cheapest option Proposed to follow the same 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 Shortest construction programme |
Lowest capacity uplift of the options If the maximum growth forecast is realised this will only provide enough capacity until 2045–2046 Future upgrades to the existing line would be required sooner if growth forecasts are understated; this may require a reconductor to the existing 110kV line. This will defer costs, however the total cost of the long-term options will be greater than option 2, with less uplift in capacity and security Lowest resilience option Engineering will be required to mitigate fault line risk Single circuit lines can be more challenging to upgrade in the future Not as resilient as option 4 |
More information
This option provides an uplift of approximately 130MW to Queenstown, which provides enough additional capacity for (at 110kV):
~18,200 homes (5kW) 70%
~520 small and medium businesses (25kW) 10% and
~104 larger commercial loads. (500kW) 20%
Estimated Cost to the Customer per year
Based on midpoint population growth scenario and current Transmission Pricing Methodology.
2032 - $330 to $550 per year
2050 - $244 to $408 per year
