Countdown to power crisis

Hydro-power lakes are at their worst levels since the 1992 electricity crisis and consumers could be three weeks away from being asked to cut back use if there is no rain, or sooner if a big station fails.

Hydro storage is down to 58 per cent of average, from 74 per cent at the start of April.

New Zealand was hit by blackouts and water heating cuts in 1992 after a similar severe drought in the South Island.

Storage is now lower than in 2003, when the last public power savings campaign was brought in.

Transpower chief executive Patrick Strange said that the national grid operator was still concerned about lake levels, with low inflows in the past fortnight.

Transpower is introducing a website today showing lake storage, water inflows and power demand.

In three weeks, if there was no rain or a big power station failed, Transpower would move beyond asking people to be prudent with power, Mr Strange said. "We would have to step that up."

In 2003 a public power savings campaign encouraged people to save 10 per cent of their power.

"We are the lowest since 1992, but we are still well above 1992 levels." But the reality was there would "probably be some rain at this time of year".

Independent energy consultants have put the risk of 1992-type blackouts at 10 per cent to 30 per cent.

Power lines companies advised customers earlier this month that power could be cut "without warning" for at least 30 minutes as the industry geared up for the growing risk of blackouts.

New Zealand's biggest power user, the aluminium smelter at Bluff, has already cut power use by 10 per cent.

Other big industrial users have been cutting back or using other power sources such as gas because wholesale power prices are four times higher than last year.

However, the power system has not yet had its first real test of a winter cold snap. Colder weather, which will drive up peak demand, is expected soon.

"The margins are tight, but providing nothing breaks we can get through them [peaks in demand]," Mr Strange said.

South Island hydro-power stations would have to run hard using available water to meet peak winter demand.

"We would have to take action pretty quickly [if a big power station failed], but it is unlikely to happen."

The system could be pushed harder, but big users would "fall off" because of even higher spot power prices.

There had been a little rain in Lake Manapouri but southerlies meant the rain turned to snow, adding little to lake storage.

"We need lots of dribbles. If we kept getting low inflows and did not get rain before the middle of June, we will have to up the ante."

Wholesale or spot prices paid by big users were four times higher than a year ago at more than 30c a unit.

- © Fairfax NZ News