What could happen: Like the grid itself, other failures tend to cascade when the lights go out. In 2003, landline and cellular phone systems still worked but were so overloaded with calls that they effectively shut down. Electric railways stopped in their tracks, flights were canceled, and gas pumps would no longer pump. Water supplies that relied on electric filtering systems got contaminated. Food and medicine got spoiled; looting occurred; people died. On the positive side, residents of large cities were able to see the stars for possibly the first time in their lives.
How long would it take to recover: From hours to days, depending on how many generators have been affected and how long it takes to restart them, says Sills. Nuclear facilities can take several days, gas- and coal-fired generators require around 24 hours, but plants that use hydroelectric power may be able to get back online almost immediately. If an adjacent grid is still operating, the dark one may also be able to tap into its reserves.
Likelihood: Low. Electricity is supplied to the United States and Canada by eight separate, regional entities, so for the United States to go entirely dark would require a coordinated attack of key substations in each grid, says Sills. That makes a worldwide blackout even less likely. Still, regional blackouts are well within the grasp of knowledgeable attackers.
How to avoid this: The technology to secure the power grid is readily available. Sills says his firm has installed protective measures for a utility serving a major metro area, but declined to name it, lest it become a target. The problem? The Federal Energy Regulatory Commission is still hammering out security guidelines for the diverse systems used by power plants, and no public utilities are reluctant to invest in costly retrofits until their solution gets Uncle Sam's stamp of approval.
Tech doomsday scenario No. 2: Wall Street gets e-bombed
News flash: In what authorities suspect was the aftermath of an electromagnetic pulse weapon, a rogue attacker took down much of lower Manhattan today -- causing equipment failures and power outages on a massive scale and shutting down financial markets across the country.
Though most commonly associated with nuclear explosions, you don't need a nuke to create an electromagnetic pulse strong enough to do serious damage. EMP devices emit extremely high-frequency signals that fry electronics to a crisp, rendering them useless. An EMP will also wipe out or corrupt any data not stored on magnetic or optical devices. Worse, EMPs are largely untraceable, because the weapon itself destroys any evidence of its use.
A van with an EMP device in the back could effectively shut down big chunks of the U.S. economy simply by driving down Wall Street with the signal turned up, says Gale Nordling, CEO of Emprimus, a company that helps enterprises protect against threats from non-nuclear EMP.
If you wanted to take out the entire continent, though, you'd need a nuke and a missile delivery system. "One bomb exploded 300 miles over Kansas could take out most of the electronics in the United States," says Nordling.
What could happen: Workstations? Dead. Data centers? Gone. Cell phones might still work, but the cell towers probably won't, rendering them useless. Your car won't start. A large enough attack will also shut down automated controls at power substations, leaving everyone in the dark. Think pre-industrial revolution days. In our scenario the New York Stock Exchange shuts down, causing shock waves to reverberate throughout worldwide markets.