It’s scary enough to envision the nation’s electrical grid collapsing under an enemy attack or because of a powerful solar radiation onslaught. But it’s even more disturbing, perhaps, to think that we might someday suffer a massive nationwide blackout because the grid simply breaks down on its own.
The big problem is that the national grid isn't like an office computer network, in which the computer on your desk could stop working without having an effect on your neighbor in the next cubicle. Instead, its far-flung parts work together and to a degree depend upon one another. That means that when one part breaks down, it can cause a phenomenon called "cascading failure," in which the whole grid progressively collapses like a stack of dominoes.
“What happens is, a failure occurs somewhere and weakens the system a bit,” Iowa State University engineering Professor Ian Dobson explained in a 2012 article. “On a bad day, something else happens. Usually it doesn’t, but on that day, let’s say, it does. If it’s a really bad day, then a third thing happens and the system becomes degraded. You’re in a situation where it’s more likely that the next failure is going to happen because the last failure already happened. That’s the idea of cascading failure.”
“What we’re talking about is the big power grid that stretches from here to Florida and Maine and Canada—everything east of the Rockies is all connected together, all humming together,” according to Dobson. “Everything in the power system is protected so it doesn't fry when something goes wrong. Things can disconnect to protect the equipment, but if you disconnect enough things, you get a blackout.”
In fact, in an article published in Nature Physics in August 2013, U.S. and Israeli physicists concluded that that’s dependent upon a number of critical nodes, as the U.S. electrical grid, such cascading failures are pretty much inevitable. One of the study’s authors, Shlomo Havlin of Bar-Ilan University in Israel, explained, "Whenever you have such dependencies in the system, failure in one place leads to failure in another place, which cascades into collapse."
We've already had at least one preview of how this would happen. In 2003, three transmission lines in Ohio failed after sagging and coming into contact with trees in the course of about an hour. That, in turn, triggered a cascading failure that surged through the Midwest and northeastern U.S. and parts of Canada, cutting off power for some 50 million people. But that was a minor inconvenience compared to the 2012 event in which three sections of India’s massive electrical grid collapsed, leaving 620 million people—nearly twice the population of the U.S.—without power for several hours in the biggest blackout in world history so far.