The next peak cycle of sunspot activity is predicted for 2012–2014, bringing with it a greater risk of large geomagnetic storms that can generate powerful rogue currents in transmission lines, potentially damaging or destroying the large transformers that manage power flow over high-voltage networks.

In the worst-case scenario, the stockpile of spare transformers would fall far short of replacement needs. Urban centers across the continent would be without power for many months or even years, until new transformers could be manufactured and delivered from Asia. No comprehensive plan exists to retrofit the transmission grid with protective devices.

“The U.S. society and economy are so critically dependent upon the availability of electricity that a significant collapse of the grid precipitated by a major natural or man-made EMP [electro-magnetic pulse] event could result in catastrophic civilian casualties,” Rep. Trent Franks (R-Ariz.) said at a May 31 House Energy subcommittee hearing on the issue.