Fault closes Otahuhu B power station

The fault that has taken the Otahuhu B power station off line could mean more water will have to be taken from already low southern hydro lakes.

Contact Energy said today the fault that had taken the 400 megawatt gas-fired station off line was expected to take about four days to fix.

The loss of power from the station comes as electricity spot prices hit record levels, while hydro lake levels have dropped to 52 per cent of average for this time of year – their lowest level since the last major power crisis in 1992.

National Party energy spokesman Gerry Brownlee said that with the second-largest thermal plant in the country out of action, the southern hydro lakes would be using water that would otherwise be held in reserve for winter.

Rebecca Wilson, spokeswoman for national grid operator Transpower, said that without Otahuhu B it might be necessary to use a little more water from the hydro lakes than would otherwise be the case.

The system was run with reserves and the generation lost from Otahuhu B would come from elsewhere, she said.

Considerable amounts of electricity were still being sent south and the industry continued to try to conserve water, she said.

Mr Brownlee said the fault at Otahuhu B should be "the cue for Energy Minister David Parker to announce the crisis measures he's been trying so hard to avoid".

A spokeswoman for Mr Parker said the industry was continuing to work together on finding ways to manage the electricity situation.

The time may come for a public power savings campaign, but right now it was not necessary, she said.

Contact Energy said a leak was discovered in one of the boiler tubes in the plant's steam generator system, forcing the closure of the plant while the fault was fixed.

The fault was expected to take about four days to repair, but the actual duration of the outage would not be known until a full inspection of the steam generator was completed, which would be undertaken when the plant had cooled today.

Contact Energy chief executive David Baldwin said the timing of the fault was unfortunate, given low hydro storage levels in the South Island lakes, but it was essential to fix the fault now.

"We're working to have the plant back up and running as quickly as possible. In the meantime, we have notified other generators and network companies so that Otahuhu's capacity might be covered with other generation options over the course of the outage," he said.

Mr Baldwin said one 100 megawatt unit at the New Plymouth power station was recommissioned yesterday – ahead of schedule – and was now operating at full load, which would help cover some of Otahuhu's capacity.

Yesterday Ralph Matthes, executive director of the Major Electricity Users' Group, said it was essential all consumers take prudent steps now to save power to avoid blackouts later, along with significant increases in future retail prices.

Wholesale spot prices at Haywards Hill (Wellington) averaged 27.2 c/kWh over May – the highest average monthly price at the North Island reference since records began in 1996, he said. Mr Matthes' comments followed figures showing last week was the highest weekly average price on record in both the North and South Islands.

Around noon today an M-Co analyst said the loss of electricity from Otahuhu B had not appeared to have a substantial impact on five-minute wholesale prices since the plant went off line about 8pm yesterday.

- NZPA