When power lines meet ferocious gales, accumulating ice or falling trees, something’s gotta give. Often, it’s the humble wooden utility pole, which snaps like a matchstick.
Last May, a line of intense windstorms known as a derecho cut a swath across Ontario. Hydro One reported 1,900 broken poles – a corporate record. Ottawa Hydro lost more than 400, along with several kilometres of power lines. Hydro-Québec replaced 1,125 poles, along with 400 transformers and 40 km of electric cable.
In late September, Nova Scotia Power reported that Hurricane Fiona’s sustained winds damaged more than 2,000 poles, leading to the largest storm response effort in the utility’s history.
Most Canadians enjoy astonishingly reliable electricity service. But according to a study by the North American Electric Reliability Corp. (NERC), an international regulatory body that monitors the continent’s bulk power system, weather is the leading cause of major transmission outages.
Hurricane-force winds and tornadoes tear down transmission lines. Storm surges flood low-lying transmission stations. Extreme heat overwhelms transformers at substations and can spark wildfires, turning poles into torches. Accumulating snow and ice can bring down even the hardiest of trees, taking lines and poles with them.
Climate change is expected to increase the frequency and intensity of extreme weather in many areas. In a report published during the summer, the NERC said extreme weather’s impact on the continent’s bulk power system’s reliability is already rising.
Many major utilities predict that climate change will take a mounting toll on their infrastructure. Their preparations are whipping up a bonanza in the utility pole business – and the consequences could show up soon on your utility bill.
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Next time you’re out for a stroll, observe the power lines around you. Particularly in old neighbourhoods, they’re likely strung from wooden poles. Treated with industrial-strength preservatives such as creosote, chromated copper arsenate or pentachlorophenol, the poles are barely recognizable from the majestic Douglas fir, cedar or pine from which they originated.
Some are supported by taut guy-wires. Often you’ll see crossarms near the top, supporting the lines.
The story of how poles became ubiquitous began in 1844. That’s when Samuel Morse (of Morse code fame) built a 65-km telegraph line between Washington D.C. and Baltimore – the first documented use of wooden poles. Mr. Morse originally intended to lay the line underground, but the first segments of wire proved defective; one of his partners suggested the quickest and cheapest way to complete the project would be to string wire overhead on wooden poles.
By the time the earliest electricity grids were built in the 1880s, the pole-and-overhead-wire approach had become entrenched.
And so it remains. Though steel and concrete poles have become common in some parts of North America, wooden poles retain their popularity. But when extreme weather strikes, they sometimes prove to be the system’s weakest link.
“It’s as simple as this, really: When you have a large storm come through, the main reason why you have outages on your distribution poles is because trees adjacent to the right-of-way fall down, hit the wires, and bring the poles down,” said Andrew Phillips, vice-president of transmission and distribution infrastructure at the Electric Power Research Institute (EPRI), an independent, non-profit research and development organization headquartered in Palo Alto, California.
North America’s leading manufacturer of wooden utility poles, Montreal-based Stella-Jones Inc., supplies all of the continent’s major electrical utilities. The company makes more than one million poles each year at facilities in British Columbia, Alberta, Manitoba, Ontario, Quebec and Nova Scotia, and throughout the United States.
The company’s utility pole sales have more than doubled since 2013. Stella-Jones chief executive officer Eric Vachon says this is partly because many of North America’s poles were installed in the decades around the Second World War. Wooden poles last about 70 years, so it’s time to replace them.
“As our customers are changing out their infrastructure, they’re turning their minds to hardening the grid,” Mr. Vachon said. “Our customers are looking for taller and thicker poles,” he added, to accommodate heavier wires and transformers, and more violent weather.
But there’s a wrinkle. According to a recent report by the North American Wood Pole Council, only about 5 to 10 per cent of trees in a typical forest are suitable for poles. The council warned that if utilities keep favouring large poles, harvesters will have to wait at least a decade longer for trees to grow sufficiently. That would increase prices and delay orders. Instead, it encourages utilities to purchase smaller poles and shorten spans between them.
A small competitor to Stella-Jones, Calgary-based RS Technologies Inc., smells opportunity. The scent is reminiscent of a freshly snapped wooden pole.
CEO George Kirby said the poles originally used to build electricity networks came primarily from old-growth forests. Today’s poles are harvested earlier, making them weaker and shorter-lived than their predecessors.
RS Technologies began manufacturing composite poles from fibreglass and resin about two decades ago; it has a plant in Tilbury, Ont., another in the U.S., and plans to open a third. The company says they are “the most resilient pole available,” impervious to rot and woodpeckers.
It also asserts that the poles are self-extinguishing, so the vast majority won’t need to be replaced even after a wildfire tears across a right-of-way. The company claims they’ll last 80 to 100 years.
Composite poles were “an order of magnitude more expensive” than wooden ones three years ago, Mr. Kirby said, but the price gap has narrowed considerably. And composite poles are lighter and can be assembled on site from segments nested together, so more can be shipped on the same truck.
The wooden pole industry isn’t impressed. A 2019 Pole Council study sputtered at “the incorrect belief that non-wood poles are somehow superior to wood poles.” The latter, it claimed, boast “much greater overload capacity” and perform better during extreme weather.
In response to the growing wildfire threat, Stella-Jones introduced a fire-resistant wrap for wooden poles. The product looks like the screen of a patio door when installed, Mr. Vachon said, but expands to a protective sheath several inches thick when exposed to flame.
Last year the wrap represented 10 per cent of the company’s pole sales. Utilities on the U.S. West Coast are the main buyers, Mr. Vachon added, but Canadian utilities such as BC Hydro and Hydro-Québec have shown interest.
Some North American utilities use concrete or steel poles. Hydro One still predominantly uses wood, but lately has deployed composites in swampy areas, ones where woodpeckers are active and in remote areas where the lower weight makes composite poles much easier to install.
“They’re a lot more expensive than a wooden pole,” said David Lebeter, Hydro One’s newly-appointed CEO, “so we put them in specialty applications.” (In his previous job as chief operating officer, Mr. Lebeter was responsible for transmission and distribution.)
Nova Scotia Power rarely uses composites. It buys mostly wooden poles treated with chromated copper arsenate from Stella-Jones, said Matt Drover, the utility’s senior director of transmission and distribution. It has also increased spending on vegetation management, to as much as $25-million a year.
At EPRI’s Lenox Laboratory in Massachusetts, the institute is examining how to give the venerable wooden pole a new lease on life. The facility is essentially one giant torture chamber for electrical components. It includes areas dedicated to testing underground explosions, chambers that simulate accelerated aging of insulators and other components, and a pole-break test area. That’s where EPRI drops poles against full-scale mock-ups of power lines, with multiple video cameras capturing the resulting havoc.
EPRI’s grand idea is using sacrificial components – for example, affixing crossarms using more fragile bolts – so that poles are spared when trees fall across the lines.
The logic is straightforward: Mr. Phillips said that replacing a snapped pole takes between 24 and 36 hours; a crossarm takes just four to six hours. But it’s a fine balance. The crossarm still needs to support loads from accumulating ice, for instance.
Utilities can also build higher. Mr. Lebeter said Hydro One is installing taller poles, which moves lines farther above vegetation. The utility is also using wider crossarms, which increases the spread between wires and decreases the likelihood that a branch will fall across multiple lines.
Another common method of hardening grids is to bury transmission and distribution lines. Known as “undergrounding,” it can improve reliability in storm-prone areas. Buried conductors are protected not only from high winds, but also heat and ice buildup.
The main drawback would be familiar to Samuel Morse: various estimates suggest undergrounding is 10 to 20 times more expensive than stringing cable overhead. Ottawa Hydro recently estimated it would cost $10-billion to bury all of its lines, and take 90 years.
Research suggests that although hardening grids will be expensive, it’s still cheaper than repairing the storm damage that could be avoided. But in the highly-regulated electricity sector, costs matter a great deal.
In its latest rate application, Nova Scotia Power cited climate change and large storms as it sought significant rate increases for the next few years. It also wants to tack on to customers’ bills something it calls a “storm rider,” intended to fund recovery from severe storms such as Fiona.
This led to a political dust-up: Nova Scotia’s provincial government intervened in the rate-setting process in November, setting a maximum allowable increase for improving reliability of 1.8 per cent over two years.
Hydro One’s investment plan envisions replacing or renewing 65,000 wooden poles and 1,500 km of transmission lines, and one in 10 transformers. Mr. Lebeter said Hydro One aims to maintain cost increases to the rate of inflation, which has been achieved to date.
“If we do this wisely,” he said, “we can do it with a limited cost increase.”