The Big Blackout – What went wrong?

While most of Ontario had power restored to them after the Big Blackout this weekend, homeowners were being asked to conserve energy, by not using appliances nor switching on their air conditioners. Unfortunately, commercial building owners weren’t apparently hearing the same requests, and desks and workplaces hastily abandoned after the 4 p.m. shut-down on Thursday, sprang back to full energy-consuming mode for days once power was returned even though the buildings were virtually vacant.
What went wrong that caused over 50 million people across Ontario and the northeastern United States on Thursday, August 14, about 4 p.m.? Most agree it has to do with an antiquated transmission system, and the vast interdependence of the region’s power grid.
According to a theory published in the Toronto Star, sourced from the National American Electric Reliability Council, the domino effect began as follows: between 3.06 and 4.06 p.m. five power lines near Cleveland shut down, forcing other grids connected to them to search for power elsewhere. At 4.08 p.m. the ensuing mismatch between supply and demand caused even greater power surges in connected grids in Canada and the Eastern United States.
At 4.11 p.m. overloaded transmission systems started to shut down to protect themselves. Within nine seconds, 50 million people, from Kalamazoo in Michigan to Ottawa in Ontario and New York City, were without power.
Dozens of transmission lines shut down and 100 power plants tripped their circuit breakers in order to protect their equipment.
The result plunged the entire area into crisis. In Toronto office workers left to find there was no subway service and buses were so scarce and overloaded the only way home was to walk. Traffic lights stopped working, telephones were dead, gas stations couldn’t pump gas, and stores locked up.
The total shut-down was over in most areas by the next morning, though restoring power had to be done very carefully in slow increments in order not to upset the applecart again. Rolling black outs continue to be a threat.
Ontario’s nuclear power plants will be the last generating plants to be restarted. They account for 25% of the province’s supply.
At the time of the blackout, Tom Adams’ of Energy Probe reported that Ontario Hydro was running 24000 MW of power on a sweltering day that saw temperatures over 30 degrees Celsius. Energy experts had been warning all summer that Ontario would hit an energy crisis, but relatively cool temperatures had not forced the situation until now.