A robotic gravity-powered generator includes two containers, one containing fluid with an inflatable bag and attached weight immersed in the fluid, and the second containing a generator. A pneumatic pump inflates the bag, permitting it to float to the top of the first container; the bag is then deflated, and moves down through the fluid due to the force of gravity. The movement of the bag up and down is converted to rotary force which operates the generator, thereby generating electricity.