Security of Supply
Despite a few small scale inflow events, national hydro storage has dropped by one percentage point to 81% of average for the time of year. This means national hydro storage now sits just below the 10th percentile of the historic range.
North Island hydro storage decreased from 116.7% to 113% of average this week, while South Island hydro storage remained relatively steady; decreasing from 79.3% to 78.8% of average for the time of year.
Storage at Lake Te Anau has improved so that it is now sitting just within its low operating range at 19% of full. Lake Manapōuri is now clear of it's low operating range, sitting at 20% of full. Lake Tekapo and Lake Pukaki continue to prop up the national hydro storage position at 64% and 76% of full respectively.
National weekly demand was 712 GWh this week, a decrease of 2% on the week prior. This decline is due to the Easter long weekend from Friday. The long weekend's impact on demand can clearly be seen in the demand graphs for all of Christchurch, Wellington and Auckland on page 4 of this report. We expect to see lowered demand continue over the next two weeks, taking in Easter Monday yesterday and ANZAC day coming up.
National demand peaked at 5,467 MW on Wednesday 13 April at 6.30pm.
National generation was 746 GWh this week. In reflection of current hydrology, hydro generation comprised just 45.7% of the total generation mix (a 14% reduction on the week prior), while thermal comprised 21.5% of the generation mix (an increase of 16% on the week prior).
Wind generation was high at the beginning and end of this week and comprised a total of 8.1% of the generation mix. This represents a 16% increase on the week prior. Wind generation peaked at 688 MW on Saturday 16 April at 2:00pm. Conversely, thermal generation peaked at 1,375 MW during a mid-week drop off in wind on Thursday 14 April at 7:30am.
Prices dropped 7% this week, to $185/MWh. Prices peaked on Thursday 14 April at 8:00am.
Some price separation was seen on 12 and 13 April due to binding constraints in the Southland region.
Reflecting the declining hydrology, the HVDC is beginning to send more generation south. This is due to thermal generation located in the North Island increasing to replace declining South Island hydro generation. This is further compounded on windy days as most of our wind generation is in the North Island.
An unplanned Pole 3 HVDC outage on Thursday afternoon occurred during a period of low transfers and had little impact on the market.
The largest solar power system on a school in New Zealand was officially opened in February 2019 at Kaitaia College. This installation comprises 368 panels.