I am curious if an idea I have will work or if it is the result of a lack of understanding of the physics involved. I am expecting to be disproved. Please excuse any lack of understanding on my part as I have no formal training in physics.
Suppose that you lifted a rock to a height of 1m. At this point, the rock will have stored a certain amount of potential energy. If the rock was dropped this potential energy will be converted to kinetic energy at which point I try to remember where I had placed my foot.
Now suppose that instead of dropping the rock, you attached it to a length of rope and let go. What happens next depends on a variety of factors.
If the rope was twisted, it could be said to be storing torsional energy. Together, torsional energy and gravity will cause the rock to spin fairly quickly. Ultimately the mass will spin past the point at which there are no twists in the rope and continue spinning in the same direction approximately the same number of revolutions. This is called a torsional pendulum and will behave this way for some time.
Now, by squeezing a rope along its length to stop that point from twisting, multiple stores of torsional force could be built up like a battery.
Also the weight of the rock could be entirely supported by a point along the rope. With the weight of the rock being supported at one end of the rope, the other end of the rope can be twisted without needing to spin the rock.
Using the spinning of the rock, we could twist the non-load-bearing end of the rope without exhausting the energy of the spinning rock thereby creating a surplus of energy as this twist can later be transfered to the next section of rope and ultimately cause the rock to spin one more time. Continuing in this manner, I believe, the rock may be persuaded to spin indefinitely until the physical limitations of the equipment are exceeded.
I do not believe that this violates any laws of physics as no new energy is being created but gravity is, in essence, being harvested by the torsional force of the rope.