Systems capable of using kinetic/inertial and renewable energy to generate hydrogen for use as a fuel in vehicles and other applications are provided, including systems in which hydrogen is generated during vehicle braking and which is operable with an internal combustion engine, and which can be retrofitted to vehicles with such an engine as well as to stationary combustion devices. Methods for generating hydrogen to power vehicles and vehicles utilizing the inventive technology, stationary devices, such as space heaters and water heaters, capable of generating hydrogen for use as a fuel additive therewith, and methods of generating hydrogen using such devices are also provided.