Here is a handy power cable that eliminates the need for an AC power adapter for your Fire TV. The Mission USB Power Cable for Fire TV allows you to power the device using your TV’s USB port. As the company explains:
The Mission USB Power Cable for Fire TV includes special circuity that increases the peak power output of the TV USB port, enabling users to provide power to Fire TV directly from the TV rather than an AC power outlet
It is compatible with all powered USB ports and helps you declutter your TV area. Costs $14.99 at this time.