National storage has remained steady over the last week and continues to indicate a low risk of shortage this winter. North Island storage remains below average at 59% of average.
We have published the next, and final, edition of the HRC 101 series. This week we discuss the Simulated Storage Trajectories (SSTs) which we produce in addition to the Hydro Risk Curves (HRCs) to indicate risk of shortage.
We have published the updated HRCs and SSTs for this month. The HRCs have increased throughout 2019 largely due to the inclusion of some short-term outages, which do not impact the HRCs beyond 2019. The HRC Update Log includes the changes to the model assumptions since last month’s update including planned outages. The SSTs have also been updated and support the conclusion there is a low risk of shortage over this winter, with no sequences crossing the 4% or 10% HRCs.
Current Situation
Aggregate New Zealand storage increased over the last week and is at 79% of total storage, this is above the historical average (113% of average) for this time of the year.
Weekly hydro generation over the last 12 months has ranged between 54% and 66% of total generation. Last week hydro generation contributed 60% of total generation.
Hydro Storage Update
Controlled storage remains above average on the New Zealand and South Island hydro risk curves.
Inflows into Lake Taupo over the last week remain lower than the historical average for the time of the year and there was a decrease in North Island storage.
South Island inflows were higher than the historical average over the last week and storage levels have increased.
The spot price, based on available final and interim prices, has averaged $106 per MWh over the last two weeks, this is higher than prices experienced this time last year.
We periodically update the base HRC data curves and the Simulated Storage Trajectory Curves. The updated files for these are available on the Hydro Risk Curve page.
Data
Last Updated
Hydro Risk Curve Data File and Input Assumptions
21 May 2019
Simulated Storage Trajectories and Assumptions
21 May 2019
Next Report
The next scheduled weekly Security of Supply Report is due Tuesday 28 May 2019.
