Summary
Security of Supply
NIWA have officially announced a La Nina climate event for this summer, which increases the likelihood of below average inflows in our South Island hydro catchments (link here).
There was little change to the national hydro storage this week, with storage remaining at 126% of average for the time of year (82% of full). Recent inflow events have reversed the gently declining trend we saw between September and October.
North Island storage decreased by five percentage points to 124% of the historical average, where inflows continued to be below the historical average for this time of year and hydro generation remained high. South Island storage, however, remained the same at 127% of the historical average. This was caused by a combination of rainfall in the South Island and high hydro generation. The rainfall has pushed Lake Tekapo above its operating range indicating spill.
Weekly Demand
National weekly demand was 738 GWh, a decrease of 13 GWh (two percent) on the previous week.
This week's national demand peak was 5,243 MW and occurred at 8.00am on Friday 26 November.
Generation Mix
Total generation was 773 GWh this week, with 90.2% renewable energy. Hydro generation continued to dominate the generation mix, particularly during the first half of the week. Hydro generation comprised 64.8% of total generation, a slight increase from the previous week. This was a direct result of the above average hydro storage. Wind generation was down from the previous few weeks, contributing to 5.8% of the total generation.
Weekly Prices
The average price at Haywards was $88/MWh, up 44% from $61/MWh last week. This is still low compared with prices earlier in the year and is reflective of above average hydro storage.
Prices at Haywards peaked at $285/MWh at 8.00am on Monday 22 November. This occurred during a period of price separation caused by an unplanned outage on Pole 3 of the HVDC link. The outage posed a risk of low residual generation for the evening peak in the North Island until more thermal generation was offered into the market..
HVDC
HVDC transfer has remained mostly northward this week due to high hydro generation in the South Island. There were fewer periods of southward flow compared with the previous week due to lower wind generation in the North Island. However, the brief periods of southward transfer during the week did occur during times of low national demand and relatively high wind generation in the North Island.
Fact of the Week
Solar panels that track to face the sun (single-axis solar tracking systems) can increase energy production by up to a third or more compared with a fixed system. This is advantageous because more energy can be produced without needing to increase the size of the system (link).
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