City left exposed to power cuts by unique situation

Auckland is effectively run on a single strand of copper, says the CEO of the Electricity Networks Association. Picture / Richard Robinson.

Experts say Auckland is uniquely disadvantaged with its lack of security of power supply compared with cities overseas - but even they have not all been spared serious outages.

New Zealand's geography, with its biggest city, Auckland, sited on a narrow isthmus, is a major handicap.

Alan Jenkins, chief executive of the Electricity Networks Association, called New Zealand a "very long and stringy" country with most of the power supplied in the south and most of the load in Auckland.

"So it is necessary for power to be moved a long way through choke points like the Otahuhu substation."

Mr Jenkins said large cities overseas, such as London, Sydney and New York, tended to have either coal or nuclear power plants relatively close to the load, and power supply came from more than one direction.

"Auckland does not have much embedded generation, whereas the world's major cities have quite a lot."

Auckland was effectively run on a "single strand of copper" compared with places in Britain and the United States where a network of supply wires from different directions created something more like a copper plate.

Even in those countries there had been rogue events and cascading failures leading to serious power outages.

But New Zealand was more exposed than most. "Few countries are as reliant on hydro-power as we are ... "

Auckland runs on a "long bare bones" transmission system with power mainly sourced from Huntly, which is a fair distance away. But at peak demand, supply comes all the way from the South Island.

Electricity Commission chairman Ross Hemmingway agreed the Auckland situation was unique given its geographical location. Other cities have a more diverse supply which increases options for fixing failures.

In Singapore nearly all the power generation comes from within the city.

Bryan Leyland, a power industry consultant, said there had been significant power failures in large Australian cities such as Brisbane, Sydney, and Melbourne.

"So they're not all that uncommon, these things do happen."

Mr Leyland said, however, the security of supply to Auckland would not meet accepted international standards. There were complicated reasons for the problem including Resource Management Act restrictions and debate over who should meet the costs of improvements.

Mr Leyland said power sources were needed north of Auckland. Possible solutions included commissioning the Marsden Point station, increasing output from the Ngawha geothermal station and building a station on the Kaipara Harbour.

* We are not alone

In 2003 massive power cuts affected 56 million people in Italy and 50 million in northeast US and Canada.

Last year 10 million people lost electricity in Moscow, 100 million in Indonesia and several million in California.

Yesterday, Cambodian officials blamed a mouse for short-circuiting a 40-megawatt power plant and cutting power to more than 40 per cent of the capital, Phnom Penh.