With hydrogen now generated and stored for future use, we now concentrate on methods of converting the hydrogen into energy. The primary method of using hydrogen in the GHE is a fuel cell, an electrochemical device that converts chemical energy into electrical energy. Though similar to batteries because fuel cells and batteries both convert energy released during a chemical reaction into electric energy, fuel (H2) can be continuously fed into fuel cells for continuous electrical power output. They are compatible with renewable sources and offer quiet operation due to their static nature. A diverse range of applications have already been commercialized, for example: in the transportation sector, in stationary power generation for residential, commercial, and industrial applications, and in the portable sector for military equipment and even toys 217 .