Considering that a tree's touching an Oregon transmission line in 1996 sparked a blackout stretching from Mexico to Canada, it's not hard to imagine how coordinated attacks on the power grid could wreak continent-wide havoc. But within five years, new computer models could have the ability to respond to disasters in real time, throwing switches and rerouting power as repercussions spread. And that could help North America's interconnected grids protect themselves in the face of cascading failures, whether touched off by trees or terrorists.

The challenges involved in counteracting threats to the grid are "similar to playing a game of chess, but a lot harder," says Massoud Amin, area manager of infrastructure security at the Electric Power Research Institute, a utility-sponsored consortium in Palo Alto, CA. The institute recently tackled these challenges alongside researchers from two utilities and 26 universities, building new computer models that respond to disturbances by breaking up a large section of the grid into smaller "islands." This interrupts cascading failures and speeds restoration of service. In successful tests last year, the models detected simulated problems, calculated the likely domino effects and remotely tripped circuit breakers to isolate the disturbances and create islands. The models then balanced supply and demand within the islands by reducing power plant output or creating controlled brownouts.

The institute expects to put the models in control of actual emergency responses by 2005, when efforts to retrofit the electrical grid with electronic controls and sensors should also be farther along. Together, such advances may help to checkmate terrorists eyeing the grid.