Disclosed is a system and method for generating and storing energy from water waves. Oscillatory motions of a floating base are transmitted to adjustable weights enclosed in a container suspended from a frame that is rigidly installed inside the floating base. The container is operably coupled to a sheave, via a crank. The movement of the adjustable weights in the container results in the movement of a sheave that is operably coupled to an output shaft that is in turn coupled to an electric generator via a network of gears. The generator supplies power to an electrolyzer producing hydrogen and oxygen from water. The hydrogen and oxygen are compressed into gas or liquid and stored in containers on-board the floating base, until they are off-loaded at a facility.