Electricity Risk Curves

Energy Security Outlook - December 2024.pdf (PDF 1.89 MB)
Controlled hydro storage has increased since the November update. As of 15 December 2025 it is at 134% of the historic mean for this time of year. This is the same percentage of the mean as the November update, but the December historic mean is higher than the November historic mean.
The risk curves for 2025 have reduced in this month's update due to an increase in forecast thermal fuel availability relative to the November update (coal stockpile, gas storage and a small increase to forecast gas production for 2025) as well as the addition of the planned TOPP2 50 MW geothermal generator (modelled as commissioning in September 2025).
None of the modelled SSTs cross the risk curves in 2024 or 2025.
To realise this reduction in the 2025 risk position means increased thermal fuel capability being brought to market by participants contracting and trading activity. This can support an increased thermal generation response under any extended periods of low inflows.
Continued focus on hydro storage and thermal fuel management ahead of winter 2025 is therefore key to reduce the security of supply risks for next year.

An increase to the modelled starting coal stockpile, an increase in gas storage levels at Ahuroa, and a small increase to forecast gas production over 2025.
Gas availability assumes that consumption by the petrochemical sector in a dry year scenario will be similar to the reduced levels observed between March and July of 2024, in line with the proposal of Methanex moving to single train operation in the near term.
TCC will be available in 2025, however it has been modelled with a limit of 3000 remaining operating hours - this is in line with Contact's public statement on 8 November.
Demand response modelling reflects the current ramp up at Tiwai. The largest demand response options have a stand-down period and can't be called next year. Announcement here.
Updates to planned generator outages and upcoming commissioning dates.
Input data is prepared as of 1 December.

The graphs below compare New Zealand and South Island controlled storage to the relevant Electricity Risk Status Curves.

To learn more about the Electricity Risk Curves click here.