CBC News Online staff
CBC News
August 15, 2003

Thursday’s huge power failure was likely caused by a relatively minor technical problem at a generating station, but so far, it’s not clear exactly what happened.

Some investigators in the U.S. said Friday that the trouble appears to have started in northern Ohio.

A spokesperson for the North American Electric Reliability Council, an industry-sponsored monitoring group, said it would take some time to pinpoint the cause.

Meanwhile, the Ohio Public Utilities Commission said it doubted the outage started in its state.

SoftSwitching Technologies Inc, a private monitoring group in Wisconsin, said the problem started in Michigan.

Cascade failure

Experts agree that the power outage was the result of what’s called a cascade failure.

Generators can be seriously damaged if there’s nowhere for them to send the electricity they’re creating. As a result, generators shut themselves off to prevent damage when the part of the grid they’re connected to breaks down.

That in turn takes more of the grid offline, causing still more generators to shut down.

It’s the same cascade effect that caused a huge power failure that struck the Northeastern U.S. and parts of Canada on Nov. 9, 1965, leaving 30 million people in the dark.

Engineers made changes to the system after that blackout but for reasons that aren’t known, the safeguards didn’t work.

President George Bush said Friday the blackout was a "wakeup call." "The delivery systems have to be modernized," he said.

"Obviously this is not going to be done overnight." Tom Adams, the Executive Director of Energy Probe, says he expects to see a lot of changes to the power grids.

"A lot of the grids have not received substantial investments for decades now," he said. "We’ve regions of North America that haven’t built any significant new transmission in 17 or 20 years."

Aside from investing in the power transmission system – the wires that connect electricity customers – Adams says there should also be changes in the way the system is set up.

"What we’ve got is a very centralized power system where almost all of our power comes from very large generators located remote from the load," he said. "That system is inherently less stable than one where the generation is more decentralized, where the generators are smaller, so losing one small piece causes less harm."

Tom Adams

A balancing act

Meanwhile, getting the power restored will be a careful balancing act, John Dalton, managing director with Navigant Consulting in Toronto, told CBC News Online.

The hydro system – when it is up and running normally – could be compared to two 200-pound men on either end of a seesaw, he said, with one man representing demand and the other representing generation.

"The system is in perfect balance. If one of the guys were to throw off a pound or two from either end of the seesaw, you wouldn’t move that much," Dalton said.

However, when the system collapses, bringing the network back up isn’t as simple as flipping a switch.

"What happens when you’re bringing the system back up – you’re at the point where you have two five-pounders, so a one pound change there has a much more dramatic impact on the system," Dalton said. "So you have to gradually, essentially bring back the system."

Utilities in Ontario are warning it could be well into the weekend before power is restored to all customers.