Security of Supply
National hydro storage increase nearly 4.8% to 79.8% of average for this time of year, to sit just shy of the 90th percentile of its historical range.
Heavy inflows in the North Island have increased North Island hydro storage by 39.1% to 111.3% of average for this time of year while storage in the South Island storage increased marginally (2.2%) to 77.4% of average for this time of year.
The Maui outage has been extended to 16 June. Methanex continue to idle one Motonui Train, helping to balance the gas system.
Contact have notified of an additional 750 running hours in closed cycle mode at TCC. This will allow TCC to run with no outages until near the end of August. The outage planned for July/August has now been deferred to early November. See here for further information.
Demand decreased slightly from the week prior to 774 GWh. Demand peaked at 6,107 MW on Monday 30 May at 5:30pm, during a period of low temperatures.
National generation was 806 GWh this week with 83% of the generation mix contributed by renewable generation. Hydro generation made up 56% of the total generation mix while wind generation increased and was more consistent than the week prior, comprising 7% of the generation mix.
Thermal generation peaked early in the week and remained relatively high throughout the week. Conversely, wind generation peaked mid-week which was reflected in relatively lower hydro generation mid-week.
The average price at Haywards was $172/MWh, a decrease of 21% from $217 MWh the week before. Prices hovered around $200/MWh during the week, with price fluctuations between 31 May and early morning 2 June associated with periods of $20-$30/MWh as well as near $0/MWh prices. The fluctuations coincided with strong wind generation and low overnight demand.
Prices peaked at $297/MWh on Thursday 2 June at 1:30pm as wind generation dropped off and demand stayed high over the mid-day trough.
Transfer across the HVDC link over the past week again reflected typical winter conditions, with northward flow during the day and southward flow at night as a result of low demand, higher North Island baseload thermal generation, and high winds.
Outages and Loss of Load
There were two loss of load events on Wednesday 1 June at 1:20pm. There was a 10 MW loss of load at Blenheim and a 20 MW loss of load at Stoke.
Reefton was the first town in the southern hemisphere to have its own public electricity supply, a 20kW hydroelectric power station built in 1888.