No 2. Free Energy Room

As with solar cells, mirrors aren’t 100 percent reflective. Even if they were, it might be possible to create a chamber where light could bounce around indefinitely. And once something with less than 100% reflectivity entered the chamber, it would absorb all the light in millionth of a second. In order to see light, it is absorbed by our eyes, so such a theoretical room would be drained of the light by our process experiencing the light through our eyes.

No 1. Free Energy Pool

Simple, you never get as much energy out of a system as you’d put in to move the water in your ring-shaped pool.