Our Market Operations Weekly Report contains the latest information about the electricity market, including security of supply, wholesale price trends and system capacity.
It is published every Tuesday. Click here to receive the report via email every week.
If you have any comments or questions please contact the Market Operations Team at [email protected].
Latest Report / More Information
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Current Storage Positions
Overview
New Zealand hydro storage remained at 102% of the historic mean last week continuing to sit close to historic averages for the time of year. However, South Island storage remains below the mean. An under-frequency event on Friday 11 July saw energy and reserve prices spike.
This week’s insight takes a look at the recent electrical islanding of the Tekapo power station that occurred between 8-10 July.
Security of Supply and Capacity
Energy
New Zealand hydro storage remained at 102% of the historic mean last week with continued inflows throughout most of the motu. South Island hydro storage remained at 95% while North Island storage decreased from 171% to 166% last week.
Capacity
Capacity margins remained relatively healthy last week with the tightest peak being on the evening of Wednesday 9 July when residual generation dropped to 505 MW. This coincided with cold evening temperatures across the motu.
The N-1-G margins in the NZGB forecast are healthy through to early August, with moderate margins through to next weekend. Within seven days we monitor these more closely through the market schedules. The latest NZGB report is available on the NZGB website.
Electricity Market Commentary
Weekly Demand
Despite total demand increasing to 829 GWh last week from 821 GWh the week prior, total demand for the time of year is lower than the last three years as a consequence of milder temperatures across the motu. The highest demand peak was 6,544 MW, which occurred at 6:00pm on Monday 7 July, coinciding with cooler temperatures.
Weekly Prices
The average wholesale electricity spot price at Ōtāhuhu last week decreased to $67/MWh from $81/MWh the week prior. Wholesale prices peaked at $1,001/MWh at Ōtāhuhu at 1:00pm on Friday 11 July during the under-frequency event which caused inter-island price separation.
Generation Mix
The generation mix last week was relatively unchanged from the week prior. Hydro generation remained at 63% of the mix. Thermal generation remained at 6% of the mix. Wind generation increased from 7% to 8% of the mix and cogeneration from 1% to 2%, which was offset by a drop in geothermal from 23% to 21%.
Tauhara power station coming offline for a period can be seen in the small drop in geothermal on 9 July.
HVDC
HVDC flow last week was predominantly northward with overnight periods of southward flow coinciding with periods of lower demand. In total, 39 GWh was sent north and 12 GWh was sent south.
Under-frequency event
An under-frequency event occurred in the North Island on Friday 11 July at 1:04pm. A Customer Advice Notice (CAN) was issued regarding this.