July's broiling heat and wind-driven storms are big risks for power outages from the dry desert southwest to the swampy East Coast. Outages are usually local, with downed lines leaving us in the dark for a few hours or perhaps a day. But what are the chances of something worse happening? What if the entire U.S. power grid went kaput?
Many experts say that's an unlikely event. The nation's power grid is a complex, yet technologically advanced, system with plenty of backup. But scenarios do exist that could lead to such a massive failure: a solar flare, a cyberattack, or even just a series of unfortunate events -- also known as a cascading failure.
"It is conceivable," said Ian Dobson, professor of engineering at Iowa State University who focuses his research in preparing for just that possibility. "If there is a series of failures, then the grid doesn't have sufficient redundancy to transmit electricity and the load is shed, that is a blackout and the lights go out."
If it's a just a matter of rebooting the system, that can be done in a couple of hours, explained Dobson. But if there's physical damage to high-voltage transmission lines, substations or other infrastructure, it could take weeks or months to replace and repair transformers or other equipment.