Abstract
Hydrogen is currently being used in many industries, from chemical and refining to metallurgical, glass and electronics, while being at the same time a promising energy carrier. Therefore the need for hydrogen is experiencing a very rapid growth. At the same time, the traditional hydrogen production methods (e.g., steam methane reforming, water electrolysis) are energy and resources intensive. Thus, research focus is on sustainable technologies that can produce hydrogen in an economic and environmental friendly way. Hydrogen production via a solar driven hybrid sulfur-ammonia water splitting cycle (HySA) developed at Florida Solar Energy Center is such a promising technology. For this reason, it is important to design and study, beyond the conceptual level, an efficient and realizable production process. Based on extensive preliminary works a state-of-the-art process has been proposed that integrates a solar-photocatalytic hydrogen production step (driven by the photonic portion of solar irradiance) with a high-temperature solar thermochemical oxygen evolution step (driven from the thermal portion) and efficient thermal energy storage as part of the cycle operation. Present work investigates the theoretical and engineering aspects of the proposed HySA process. It also provides an updated assessment and discussion of the related cycles and developments, of the photocatalysts, and analyzes the thermodynamics and implications of the reactions involved.
