Close call adds weight to plans for extra power line

Cloudy weather and showers had power companies breathing a sigh of relief yesterday but the country's electricity grid minder says this week's close-call bolsters its argument for a new transmission line.

"Our forecasts indicate that even when all generation is available, demand will meet supply by 2010," said Transpower spokesman Chris Roberts.

The state-owned enterprise wants to build a 220km power line, on pylons up to 70m high, from Whakamaru in south Waikato to Otahuhu.

The $500 million line has drawn protests from many of the 1000 landowners whose properties it would cross.

But Transpower says it is restricted in the amount of electricity it can send north of Taupo from lower North Island stations and from South Island hydro lakes because the existing line simply isn't big enough.

The prospect of power cuts in the upper North Island was raised this week as soaring demand coincided with dwindling supply.

And in the Deep South, Comalco has cut production by 5 per cent at its Tiwai Pt aluminium smelter in Bluff because of rising spot power prices and is warning that the country may be heading for an electricity crisis.

Managing director Tom Campbell said prices on the spot market had tripled since the New Year, increasing the company's electricity bill by up to $40,000 a day. 

However, Electricity Commission chairman Roy Hemmingway said the price increase was because of short-term factors that would ease. These included maintenance work at a North Island power station and higher summer temperatures in the past two weeks.

Lake levels were high, and the commission was confident the country was not heading towards a 2003 situation, he said.

The problem Auckland faced involved a combination of air-conditioners being wound up just as the Huntly Power Station drastically cut generation.

The station is restricted in how much warm water, used to cool its plant, can be discharged back into the Waikato River. The river is at bath-like temperatures - 24.5C on Thursday - when the maximum temperature allowed under Huntly's resource consents is 25C.

The station drastically cut production to avoid having to shut down altogether, generating just 45MW on Wednesday when normally it would produce 500MW to 600MW at this time of year. Its maximum generation capacity is 1000MW.

Transpower sent two warning notices to industry players but in the end no power cuts were necessary.

Yesterday, Huntly was generating around 100MW and demand had dropped to 1400MW (Friday is traditionally a low-demand day).

In contrast, on Wednesday demand hit 1500MW and available supply was just 1580MW.

The station's operator, Genesis Energy, hopes a new $520 million gas-fired station alongside the existing coal-fired facility and not dependent on river water will be commissioned by next year.

With the traditional weekend drop in demand and cooler weather forecast, summer power cuts look less likely. But Transpower says a long-term solution is needed.

- additional reporting: NZPA