The North American power grid is an incredibly complex system,
with a web of more than 340,000 kilometres of high-voltage
transmission lines connecting thousands of generating stations,
tens of thousands of transformers and control stations, and
millions of homes and businesses. It's often taken for granted —
until the lights go out.  Mother Nature has a way of finding
weaknesses in the system and wreaking havoc on a grand scale.
Besides regular localized power failures caused by storms, she's
managed to take out electricity to huge swaths of North
America's grid at least once each decade since the 1950s.  From
each major failure the engineers have learned new lessons, and
as they make the electrical grid "smarter" they're also trying
to make it tougher. But are we any better prepared today for
what the environment throws at the continent-spanning power
system that has become crucial to modern life?   On March 13,
1989, for example, a violent solar storm knocked out power
across Quebec for more than nine hour