Lake Pukaki, formed by Tasman Glacier and renowned for its turquoise blue water Photo:
Transpower says that allowing the major South Island hydro lakes to be drawn down further would leave the country exposed to rolling blackouts, in a worst-case scenario.
Electricity generators want to access what is currently contingency supply - for an emergency - in order to lower wholesale prices.
Lakes are currently at their highest levels since mid 2023, but last year Transpower did permit access to what it terms the 'fuel of last resort' because it was a dry year.
In a new report, Transpower finds that allowing access to contingency supply at the big South Island lakes could unlock $38 million a year in lower electricity prices.
But, under a stressed scenario, involving a dry year, low wind farm output, and key power plants being closed - there would need to be rolling blackouts, which could cost to the country $440 million.
Kathryn speaks with Chief Executive James Kilty.
