Dam spills water due to fall in electricity demand

The Level 4 lockdown has contributed to an 8% decrease in electricity demand in the South Island, compared with the same time last year.

Contact Energy spokeswoman Leah Chamberlain-Gunn said while households were staying at home and using more electricity, much lower activity in the industrial sector had resulted in an overall reduction in demand.

‘‘Nationwide consumption reduces during lockdown as industrial processes stop and commercial business turn their lights off,’’ she said.

However, the company was still carefully managing South Island power generation, due to an unplanned high voltage direct-current (HVDC) cable outage last week.

Water is spilled from the Clyde dam. PHOTO: SHANNON THOMSON
Water is spilled from the Clyde dam. PHOTO: SHANNON THOMSON
The cable — critical to the route of electricity supply to the North Island — fell across State Highway 7 in North Canterbury.

It is scheduled to be repaired by 4pm today, after high winds previously affected Transpower’s ability to complete the repair.

The outage reduced the cable’s capacity by up to 50% during peak periods, affecting every South Island generator’s ability to get electricity from the South Island to the North Island, Ms Chamberlain-Gunn said.

With transmission to the North Island limited and snow melt increasing due to warmer weather than usual in the lockdown period, Contact had more water than necessary for current demand but little ability to store it.

As a result, the company opened the Clyde dam spill gates yesterday.

The Clyde dam was part of the ‘‘run of river’’ Clutha scheme with minimal storage capacity.

- By Shannon Thomson

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