last summer I can remember saying that we had not had a power outage since living in TV....then 9 years.....the very next day our power went out for a couple of hours!!!!
Yes back up generators are allowed. There are the portable and the fixed installation (which is no more unsightly than pool and spa and waterfall equipment).
The fixed installation is more expensive, but can have significantly more power...as in whole house....and works automatically...the power blinks off then on comes the generator and a blink later back in business.
The portables are usually smaller in capacity and target specic circuits. Even if one does not own a generator, when building new, have a circuit put in place for a generator. Ya never know.
Regarding the "big one" getting ready requires more than being able to light the lights and watch television.....remember the better prepared you are the more you will find how many friends you never knew you had
btk