Summary
Security of Supply
National hydro storage increased this week to 109% of average for the time of year (69% of full). This was the result of above average inflows in the South Island and average inflows in the North Island throughout the week.
North Island storage increased seven percentage points to 72% of the historical average, and South Island storage increased by five percentage points to 114% of the historical average.
Weekly Demand
National weekly demand dropped 66.5 GWh (eight percent) on the previous week. This is likely due to decreased commercial/business load following the onset of the National Alert Level 4 Covid-19 lockdown mid-week.
This week's peak was 6,419 MW and occurred at 6pm on Monday 16 August 2021.
Generation Mix
Total generation was 835 GWh this week, with hydro making up 57%, and thermal 13% of the mix. Wind generation was high at 67 GWh, or 8% of the mix; a slight increase on last week.
Weekly Prices
The average price at Haywards was $100/MWh, down 65% from $284/MWh last week. From 18 August prices were materially lower than has been seen recently.
On Tuesday at 3.30pm there was an unplanned outage on Pole 2 of the HVDC system due to a fallen conductor in the South Island high country. This lead to high energy and reserve prices in the North Island up to, and over, the evening peak. This included the peak price for the week which was $514/MWh.
Inter-island price separation continued to be experienced through to Sunday as a result of this outage and subsequent bipole outages over the weekend. Pole 2 is currently expected to be back in service by the end of Thursday 25 August. Benmore prices fell as low at $0.01 during the week.
High North Island reserve prices were also observed at times during the week with greater than usual North Island reserves being required to cover the risk of loss of the remaining HVDC pole.
HVDC
HVDC transfer has remained Northward throughout the week. Weekend bipole outages can be seen as areas of zero transfer on the morning of 21 August and during the day on 22 August 2021.
Fact of the Week
Electric eels can create shocks up to 600 V. This is more than two times the amount of a standard household power outlet.
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