“Robots are better than animals in almost every way. Well, they’re better in some ways, I guess. I mean, robots are occasionally okay at some things. A few things. None of those things are energetic autonomy: the ability to operate continuously and indefinitely without dependence on humans for refueling. There certainly are robots that operate autonomously for long durations, and they’re either feeding off of radioactivity, or they’re relying on solar panels that don’t work half the time. A better option (at least in some situations) might be robots that forage for food like animals do, taking care of their own energy needs all by themselves. This is only a slightly crazy idea (although at one point it was briefly the craziest idea ever), and fuel cells that are full of living microbes are a real thing. At the Bristol Robotics Laboratory, in the United Kingdom, they’ve been developing a robot called Row-bot that can swim around, harvesting energy directly from the water using a microbial fuel cell as an artificial stomach.”