Abstract
Unlike other fuels, hydrogen can be generated and consumed without generating carbon dioxide . This creates both significant engineering challenges and unsurpassed ecological advantages for as a fuel, while enabling an inexhaustible (closed) global fuel cycle based on the cleanest, most abundant, natural, and elementary substances: , , and . If generated using light, heat, and/or electrical energy from solar, wind, fission, or (future) fusion power sources, becomes a versatile, storable, and universal carbonless energy carrier, a necessary element for future global energy system(s) aimed at being free of air and water pollution, , and other greenhouse gases. The case for hydrogen rests fundamentally on the need to eliminate pollution and stabilize Earth’s atmosphere and climate system.