Transpower is not going to change the way it calculates the Hydro Risk Curves following Genesis Energy warning about challenges getting fuel supplies in the future. However, it will be adding an extra validation step around assumed thermal fuel consumption and available supply
Hydro Risk Curves (HRCs) are intended to give early warning about possibly electricity shortages and Transpower did the review in response to fuel supply information provided by Genesis.
In late 2017, it advised the system operator of their contracted fuel supply, noting challenges and risks to procuring additional fuel over and above presently contracted quantities.
Transpower received a mixed response to the idea of changing the input assumptions on thermal fuel limitations in the HRC. Concerns over the reliability of data and the long lead times in securing additional fuel were cited as reasons not to change the modelling.
“We propose including an additional validation step which compares assumed thermal fuel consumption with available supply each time we update the HRCs. We also propose to make the information used in the validation step available to participants so they can make their own assessment of thermal fuel supply risks.”
If the validation did show more fuel was going to be burnt than there was available the HRC would reflect this.
validation would require the monthly supply of data
• Huntly coal stockpile (the final stockpile at Huntly), and aggregate delivery quantities
• Ahuroa gas storage
• Gas production station availability, including planned outages
• Gas transmission availability, including planned outages
• Non-electricity gas consumption
• Diesel storage and replacement rates
• Heat rates for conversion of thermal fuel into electricity.
Submissions on the proposal close on July 6.
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