I hate to break it to you but most of our power stations are vulnerable to attack already. Certainly anything near the coast could be taken out by our major adversaries, even with conventional attack.

For a lot of plants, an anonymous cyberattack could probably do it. That'd be way worse than an attack to geostationary, which very few actors could manage, and probably nobody could pull off anonymously.

Space junk seems a more serious problem:

https://physicsworld.com/a/space-debris-threat-to-geosynchro...

I've seen various proposals to clean it up but it'd take some work.