New Zealand and South Island storage are both in the Normal range.
- Electricity Risk Curves
New Zealand controlled storage is above average and South Island controlled storage is above average. The graphs below compare New Zealand and South Island controlled storage to the relevant Electricity Risk Status Curves.
The graphs below compare New Zealand and South Island controlled storage to the relevant Electricity Risk Curves - Percentage Risk.
Click here to learn more about the Electricity Risk Curves and thermal fuels validation
- Electricity Risk Curve Files
Latest New Zealand Electricity Risk and South Island Electricity Risk Curves [ pdf 628.95 KB ] Electricity Risk Curve Data [ xlsx 56.33 KB ] (Effective from 24 September 2021)
- Simulated Storage Trajectories Files
Simulated Storage Trajectories [ pdf 300.45 KB ] (Effective from 24 September 2021)
- Assumptions and Update Logs
Electricity Risk Curve and Simulated Storage Trajectories Assumptions [ xlsx 47.65 KB ] (Updated 24 September 2021) Electricity Risk Curve Update Log [ pdf 5.85 MB ] (Updated 24 September 2021) Nova Energy - Thermal fuel disclosure - 1 April 2021 [ pdf 92.28 KB ]
Electricity Risk Curve and Simulated Storage Trajectories Assumptions [ pdf 357.49 KB ] (base document effective from 12 May 2021)
Simulated Storage Trajectories Reduced Gas Demand Flexibility [ pdf 301.63 KB ] (May 2021) ERC Reduced Gas Demand Flexibility Scenario [ pdf 814.83 KB ] (May 2021) Simulated Storage Trajectories Reduced Gas Demand Flexibility [ pdf 1.47 MB ] (March 2021) ERC Reduced Gas Demand Flexibility Scenario [ pdf 1.59 MB ] (March 2021) Reduced Demand Flexibility Scenario ERC [ xlsx 13.9 KB ] data (March 2021) Simulated Storage Trajectories No Thermal Deratings [ pdf 323.93 KB ] (December 2020) ERC No Thermal Constraints Scenario [ pdf 558.69 KB ] (December 2020)
For security of supply purposes, hydro storage is divided into two categories; controlled and contingent storage. Generators can use controlled storage at any time, but contingent storage may only be used during defined periods of shortage or risk of shortage. During sustained dry periods, controlled and contingent storage are important indicators of overall supply risks. Storage is expressed in gigawatt-hours – GWh (a measure of the energy that can be produced using the water).
Storage increased in the North Island and increased in the South Island over the last week, with South Island storage at 78% of full and North Island storage at 78% of full.
- Lake Levels
- Island Inflows and Storage
The charts below show storage over the last 13 weeks and rolling 7 day inflows for the last year in North and South Islands.
- Over the last week (Sunday to Sunday) available storage in the North Island has increased and the South Island has increased.
- Inflows over the last 4 weeks (Sunday to Sunday) in the North Island have been below average and in the South Island they have been above average.
North Island South Island
- Contingent Storage
Contingent storage is stored hydro that is only made available for generation at specific times to mitigate the risk of shortage. Current available contingent storage is shown on the following graph.
For more information on contingent storage and the conditions of its use, refer to the documents below.
Contingent Storage additional information [ pdf 167.95 KB ] SOS101 - Contingent Storage [ pdf 175.52 KB ]
Demand, generation mix, HVDC transfer and prices can all indicate the market response to the current security of supply climate.
Renewable generation over the last seven days was 91% of total generation, with hydro generation accounting for 63% of total generation.
- Weekly Generation
Electricity consumers range from large industrial sites (the most significant is the NZAS aluminium smelter at Tiwai), down to individual households. Almost two thirds of national demand is located in the North Island. New Zealand's annual electricity consumption ('demand') is nearly 40,000 gigawatt-hours (GWh). If demand differs from expected, it may impact on security of supply.
Hydroelectric generation contributes around 60% of New Zealand's total electricity supply, with many generators of widely varying sizes distributed throughout the country.
- HVDC Transfer
The ability to transfer electricity from one island to the other is an important aspect of managing security of supply, particularly as there are no thermal stations in the South Island to call upon in times of low hydro storage. Net weekly HVDC transfer is shown in the chart below with north transfer from Benmore to Haywards and south transfer in the opposite direction.
- Wholesale Spot Prices
Spot prices can be an indicator of security of supply risk. Typically they rise when supply is tight, such as during 'dry years'. Weekly 7 day rolling spot prices for each island are shown in the graphs below. The corresponding prices for the previous year are also included for comparison.
We run security of supply workshops on topics of interest to the industry. The 2021 Workshops on Security of Supply are linked below.
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Includes information on the Annual Assessment and Transpower policies related to Security of Supply: the SoSFIP, EMP, SOROP and Outage watch List.
There are currently no consultations on security of supply.