The heat wave that wilted eastern North America in early July 2010 is similar to the conditions that led to the Northeast Blackout of 2003 and renewed debate over whether it could happen again.
After the outage — which on Aug. 14, 2003, left 50 million people in Ontario and eight states without power — power companies changed their practices to address the cause, but an industry expert said it's not enough.
"It's not a matter of if, it's a matter of when," Otto Lynch, vice-president of Power Line Systems, told CBC News.
"Is there going to be another one in 10 years? Yes. I'd say there's pretty much a 100 per cent chance."
Lynch's firm, based in Madison, Wis., makes software for overhead power lines, in part aimed at avoiding another big blackout. He was also called upon by the American Civil Engineering Society to work on the energy category of its 2009 annual report card on the state of American infrastructure.
What happens in the U.S. matters to us in Canada because the North American power grid is a single, integrated system. That fact was underscored when a single tree in Ohio triggered a complex sequence of events that created the worst blackout in North American history.
Hot weather was the cause, for two reasons: the heat made the lines expand and droop closer to the ground, coming closer to trees; and increased demand for electricity for air-conditioning resulted in higher voltage across the lines, which made them sag even more.
When lines arc to a tree, the surge trips breakers in the system and power must be transferred onto other lines, increasing the risk of surges on those lines.
A 'gross exaggeration'
Pierre Guimond, CEO of the Canadian Energy Association, which speaks for the industry, called Lynch's claim that another outage is a certainty a "gross exaggeration."
Guimond said the industry has made strides in isolating circuits to avoid cascading effects from a single outage, in reducing line contact with foliage and in introducing new technology to guard against future blackouts.
"Every utility in Canada and every utility in the United States has been working … to put in place and adhere to a series of standards that will ensure that reliability is reinforced throughout the grid," he said.
"We know what the reliability looks like for the next little while and [it's] not a problem."
The international regulator set up after the 2003 blackout, the North American Electric Reliability Corporation (NERC), said it is clamping down. By the end of 2009, it was processing 1,950 possible violations of utilities' compliance with standards, a 266 per cent increase from the beginning of the year.
"If anybody has a tree violation (that shuts down a line) ... basically, it's a million-dollar fine," said Lynch.
Power firms also increasingly use sophisticated helicopter-borne laser surveying to find problem trees along kilometres of power corridors, but Lynch said nothing is fail-safe.
"It's a big problem, because if you just go out on a normal day, the [wires] are really high and everything looks fine," said Lynch.
But the problem is anticipating how much heat and wind will affect the tendency of the line to move closer to trees.
Capacity real issue
Lynch said the real issue is that there isn't enough spare capacity on the grid.
"We just need more lines," he said
He blamed what he called excessive regulation in the U.S., and public opposition, which has delayed approvals for new transmission lines by a decade or more.
Some in the industry say the ultimate answer is distributed power generation, with smaller sources of electricity widely distributed, to reduce the need for transmission lines.
But that system — if it ever gets fully built — is still years away. In the meantime, Lynch said, the North American power grid is under stress.
North American grid 'very stressed'
"It's very stressed," he said. In its report for the American Society of Civil Engineers, his committee rated grid reliability at D+, "and some people [in the industry] would argue that was too high," he said.
Another issue is aging infrastructure.
"Forty or 50 years ago, we had the best transmission grid in the world," said Lynch. "We have the same grid today.
He blamed deregulation for driving utilities to be highly competitive and to focus on short-term profits. And maintenance doesn't immediately generate profit.
"It's hard to get an immediate return on your investment for just replacing existing components that haven't failed yet," he said.
"Ideally you're supposed to change your oil every 3,000 miles. We're not doing that in our industry. We're changing the oil when the red light comes on."