The power company has been spilling water for more than a month from Lake Pukaki, one of the largest lakes in the country. It increased the release to 500cumecs this week.
About 15GWh was being spilled every day, which Meridian described as moderate. The company said it was carefully managing the entire Waitaki hydro scheme so that we can maximise generation while still safely releasing excess water.
It was the largest spillage in the Waitaki Hydro system since 2020.
But Meridian Energy was looking at making changes to Lake Pūkaki as gas reserves drop away and more hydro storage was needed.
Meridian Energy development general manager Guy Waipara said though it was early days some work had been done looking into the future.
"Lake Pūkaki and the Waitaki hydro scheme are the backbone of New Zealand’s electricity system, and we believe access to additional hydro storage is essential for security of supply," he said.
"The sudden decline of gas as a firming fuel has put additional pressure on New Zealand’s electricity industry, and like others we have had to increase the size of our investment over the coming years and think more broadly about how we produce electricity.
"Making the most of our hydro storage is one way we can secure New Zealand’s electricity supply. Our Hydro Development Team is building a pipeline of opportunities, and the initial focus is our existing Pūkaki and Waiau catchments.
"This will begin with refreshing a number of historical projects and concepts, as well as more recent opportunities."
Meridian has applied for fast-track application to lower the lake below its minimum level for a three-year period though 2028 for civil works at Pūkaki Dam to improve the structure’s resilience to wave action during lower lake operational levels.
It had also discussed with investors in November a plan to raise Pūkaki, New Zealand’s largest hydro storage lake, as well as build a new dam and drill a tunnel in the Southern Alps to divert water into the lake, Stuff reported.
It was looking to raise Pūkaki by about 5m which would flood some farm land.
The idea was only in the very early stages, and more investigations were needed to be carried out.
The company would face some major barriers, building a tunnel near Mt Cook in a national park, being one of them.
The Clutha River which has two power stations on it run by Contact Energy was also a run of the river scheme which uses Lake Hawea for storage but only at limited lake levels.
Meridian also confirmed yesterday a boat boom on Lake Pūkaki suffered damage from a large storm event in October. The boom at gate 18 was still in place and would be fully repaired, but the design would change to improve its strength.
