Energy storage is replacing small backup gasoline generators. They are quiet, clean for the environment, connect with smartphones to keep you updated on their status, utilize solar, wind, hydro and the grid for charging.

When a power failure occurs the transfer for power is automatically done to keep your sensitive equipment online and also charge your electric vehicle.

Here are two links with reviews and comparisons:

This is a review of battery backup systems.
This is a comparison between a home generator vs. a backup battery solution.