Unfortunately simply using renewables alone is t enough to decentralize them. Lately Texas has been having near energy shortages and part of the problem is a few unexpected central outages at fossil fuel plants, but another is the vast majority of wind turbines are built in one sunset of the state, so if wind is low there it can (and has) cause massive decreased in available energy, far larger than a couple traditional large scale nuclear plants when other parts of the state are under fire warnings because of high wind and dry conditions. Of course this isn't an issue with the technology itself, but rather a problem with implementation. The issue isn't with what was built, but the lack of building more across the state (or joining one of the two larger grids to further decentralize power production over a broader area)

Anyways, another issue with security is centralized power production make a good target for disruption. And if you have the side effect of causing a meltdown...