The consequences of a successful EMP attack would be devastating if the power industry isn't prepared. If the all the power generation plants were knocked out and all circuit boards and electrical devices were fried we would be toast. If William R. Forstchen's speculation in "One Second After" are halfway correct, many if not most Americans would be dead within a year either from disease, malnourishment, or murder.
The theory now is that there are players out there with the capability but not the desire to pull the trigger. And there are players who would pull the trigger but lack the capability. Some day a player will emerge with both the desire and the capability.
Meanwhile, a power grid knockout from a cyber attack might be a little less tumultuous since it wouldn't knock out our battery powered devices, but the chaos resulting from a blackout lasting more than a few days would leave a wake of tragedy.
We sincerely hope that the power companies have taken the threat seriously and have hardened their systems, sealed off their computers from the internet, and upscaled their vigilance. And it's encouraging to see that there's a Grid Security Exercise scheduled in November to test power companies' vulnerability to an attack.
We may never learn the results from the exercise -- and maybe we shouldn't -- provided the right people act on the lessons they learn.