There are a few kinds of planetary catastrophes that we can reasonably anticipate, some of our own doing, like a major thermonuclear war or catastrophic global warming. There are also some that are beyond our ability to control, like a major cometary impact. It seems that we narrowly missed a bad one in 2012, a gigantic solar coronal mass ejection that narrowly missed the Earth. The damage such a "space weather" event would do is mediated by the large induced electric fields it would generate, which very plausibly would fry all sorts of electrical and electronic equipment, including power lines, generators and all those other devices our lives now depend on.
The good news is that there are lots technological measures that can be taken to mitigate the worst effects of such an event. The bad news is that hardly any of them have, in fact, been implemented. Big coronal mass ejection events are not rare, like cometary impacts. We are very likely to be in the path of at least one in the next hundred years. there is no good reason not to prepare.