Extreme space weather, which happens randomly once in a while, could destroy the power grid in the affected region.

Our capacity to repair large industrial systems is limited to a certain number per year. If one blows out, it can be handled soon. If 10,000 blow out, they may have to queue for years -- after waiting for the systems needed for rebuilding to function again.

The good news is that distributed renewable generation capacity, which we need to avoid almost certain disaster from global heating, is most of what we need to prevent this problem.