Simon Wilson: The price of power in a stormy city

Power went out to 180,000 homes and some still don't have it back on. Trees were damaged on most streets in Auckland, and more than 1000 fallen trees and large branches have been cleared away. Nearly 100 large trees were ripped right out of the ground.

"Unprecedented damage," says Simon Mackenzie, group chief executive of power company Vector.

Trees grow fast in Auckland and we have a lot of them: 4.5 million at last count. Heavy rain quickly softens the ground. When the wind gets up to 70km/h, vegetation damage will occur.

During last week's storm, in west coast locations like Piha and Manukau Heads, it roared in at over 200km/h. Large parts of urban Auckland experienced 140km/h winds, and you can add the "thumping effect" on top of that.

It's Auckland, but not as we used to know it. It's the new Auckland.

"We're not talking about weather," says Chris Darby, chair of Auckland Council's planning committee. "This is climate change. We've just had a little taste of what's to come."

A tree damaged by the storm that hit Auckland on April 10 was still affecting power lines on Charlton Ave, Mt Eden three days after Vector was alerted.

But are we ready? More to the point, is power company Vector ready?

Not in terms of communication, certainly. Mackenzie says their "customers updates" during the storm and after were "not up to the standard I'd like".

A lot of that was due to problems with the company's much-touted but hopelessly inadequate app. It did not offer good lines of communication to Vector, it provided contradictory, old and inaccurate information, and sometimes its responses seemed completely random.

"The app just didn't cope with this event," says Mackenzie. "To be blunt." He thinks maybe Vector needs "a different type of communication channel".

Communications are always difficult whenever customers want specific answers. "I'll give you one example. We had a crew out in Coatesville, they were told there were two trees down, so they thought that might take four or five hours and that's what the customers were told. But when the crew got there they found there were 26 trees down."

Mackenzie is proud of the work his crews have put in to restore power to the city. And they're still hard at it. But it's clear from the way he talks there are no easy ways to guarantee uninterrupted supply.

Take the question of keeping trees clear of power lines. Regulations set by MBIE, the Ministry of Business, Innovation and Employment, state what they can cut. They have no authority to cut vegetation back further than 1.5 metres from the main power lines on arterial roads and a mere 0.5 metres from the lines on a suburban side street.

"We were getting lines brought down by trees that came from the other side of the road," says Mackenzie. "Broken branches flying through the air."

So should the lines be underground?

Already, 55 per cent of Vector's network is underground. That includes all new developments and many parts of the city where old lines have been replaced. Vector spends $10-$12 million a year replacing old overhead lines, especially in at-risk areas. That includes places where cars keep hitting the poles. (That's a big issue in Auckland: we've had 182 fatal and serious crashes where a car has struck a pole in the last five years.)

A car sits under a fallen power Lines on Marsden Ave, Mt Eden after strong winds and heavy rain lashed the Auckland region last week. Photo / Michael Craig

Of the 45 per cent of power lines still above ground, 60 percent is in the north and northwest, much of it in small town and rural areas.

Undergrounding is not easy. The work has to be coordinated with Chorus, so broadband cabling goes in at the same time. Street lighting needs to be redesigned and footpaths often need to be re-laid.

The lines have to be at least a metre down, often more, and in areas of volcanic rock that means a difficult dig. Regulations state they can't dig under the drip lines of trees, which limits where the lines can be laid.

Is undergrounding the whole urban area even possible?

"It's possible," says Mackenzie, but it's very challenging. The costs are extremely challenging."

He says undergrounding costs from four to 10 times as much as running the cables above ground. Vector's rough estimate is that to put all remaining cables underground, just within the urban limits, never mind about the west coast, Riverhead and all the other exposed rural areas, would cost about $3 billion.

"That's equal to the entire value of our current asset," says Mackenzie.

A question for Auckland, right there. What does this cost-averse city want to pay for a secure power supply?

Still, Mackenzie says network resilience is high on the agenda and there are things they're doing already. In Kawakawa and Wellsford, for example, Vector is building two micro-grids, where the power will come from solar batteries backed by diesel generators. Self sufficiency, with added environmental benefits.

It's an approach that already works in some other isolated parts of the country, and in some Pacific Island territories when disaster strikes. Many of the other more isolated parts of the city could use it too.

To limit the threat of rising sea levels, new substations are sited higher above sea level.

"Smart poles" can address the issue of trees on suburban streets. With these, the lines are bundled and strung higher so they're less likely to be in your vision line and more likely to be out of the way of wayward branches. Beyond that, there's some tough talking to do with Auckland Council, MBIE and the government about how best to manage those trees.

Another problem? Auckland's growth. "We've budgeted to spend about $2 billion over the next seven or eight years," says Mackenzie. "That's just to accommodate new growth." He says they can fund the work, but it does put a brake on what else they can do.

Is that a problem for the existing network? Does all this add up to infrastructure that's overworked, too old and unfit for purpose?

"I don't know why you would think that," says Mackenzie. He says the average age of the lines is 20 years, and they should last 40. "You could say the network is in its midlife." Older lines, he says, "are identified and in replacement programmes".

Health and Safety regulations mean they no longer work in a "live line environment", which requires more planned outages when maintenance – of the network and of the trees – is required.

And then, guess what, there is the problem of the traffic. Vector vehicles are not allowed to use rooftop flashing lights, so they can't get through the congestion quickly even when they need to. Mackenzie tells a story of a truck stuck in traffic for 90 minutes, trying to get to Freemans Bay. The job itself, when they finally arrived, took just five minutes.

Auckland infrastructure: turns out the problems all join up.

Worried about those damaged trees?

The council says anyone concerned by weakened or damaged trees on public land that are directly on or very close to power lines should call its contact centre immediately on 09 301 0101.

It says if you have weakened or damaged trees on your own property you should contact an arborist as soon as possible. Keep a safe distance from those trees and, where it's safe to do so, keep vehicles away from them too.