“The exercise was held from May 8 to 9, 2024, at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and at a Federal Emergency Management Agency (FEMA) site in Denver, Colorado.”
Article refers to a PDF of the report it’s based on:
https://www.jhuapl.edu/sites/default/files/2025-04/Space-Weather-TTX-Report-Summary-v3-FINAL.pdf
I’m glad this threat is at least starting to be taken seriously. As an amateur radio operator, I got incredibly interested in how the weather on the sun affects radio propagation and power management here on Earth.
Better a CME than an EMP just simply because there is at least some time to prepare for a massive CME. Whereas an EMP has absolutely no warning whatsoever.
In the event of a massive CME off-grid homes and buildings are likely to fare much better because they are not connected to the power grid. The problem comes with long transmission lines where incredibly large charge differentials can build up over distance. shorter wires can’t build up nearly the same amount of charge differential.
Edit: I feel it’s important to mention that grid tie systems are going to be just as vulnerable as on grid because you still have the grid actually physically connected to the building.
It’s worth noting that even though a building might have solar, the systems usually disable themselves in the event of a blackout to prevent back feeding into the grid.
That’s known as a grid tie system and my edit mentions that. The only way it’s going to help is if the grid is physically disconnected from the building as in the wire is not connected to the building at any point.
That wouldn’t be an off grid building then.