While generators make a lot of sense in an emergency situation, they do have some tactical downsides. First of all, most generators are relatively loud when they are running, and when coupled with a grid-down situation in which everything around happens to be very silent because the power's out, you can see how being loud is a disadvantage. Essentially, everyone within a two-mile radius will hear your generator. Perhaps they will come inquiring as to why it is that you're so well-prepared while they aren't. Additionally, there is the problem of fueling that generator; you need to have adequate stores of gasoline, diesel or propane, and not only that, you need to have oil and filters to provide the necessary oil changes, which increase in frequency the more you run the generator.