The role of solar thermal hydrogen production technologies in future energy solutions: A review

Abstract

Hydrogen fuel is gaining appreciation as one of the primary agents in the shift towards sustainable energy systems because of its capability to generate energy without emission. With around 96% of hydrogen production relying on fossil fuels, the growing global demand for hydrogen raises environmental concerns. This situation makes using non-renewable resources even more problematic, especially since hydrogen is often promoted as a clean energy alternative. Among renewable options for hydrogen production, solar-based methods have attracted considerable interest from researchers. These methods primarily include PV-to-hydrogen and solar thermal-to-hydrogen technologies. PV-to-hydrogen, which uses electricity from photovoltaic modules, has low solar-to-hydrogen efficiency besides being costly. Hence, solar thermal-to-hydrogen methods unlock the great potential of using solar energy to produce clean hydrogen, mainly because of recent advancements in concentrating technologies. Although numerous developments have occurred in Solar Thermal Hydrogen Production (STHP) production, the need for more comparative surveys is significant and concerns relatively recent literature. This study mainly includes solar thermal hydrogen production technologies, corresponding Concentrated Solar Power (CSP) systems, and its cost/benefit analysis. This research fills the knowledge gap by analyzing all solar thermal hydrogen production pathways to compare the identified pathways’ energy, carbon footprint, and cost intensity. It guides towards the solar thermal routes most favorable for hydrogen generation and how these methods are effective in time and toleration of pollution. The work utilizes a systematic review approach by examining the evidence from the published literature and databases limited to solar thermal hydrogen production technologies. It was found that thermochemical water splitting is the top option if efficiency is the top priority. HTWE and solar methane cracking are the top choices for low environmental impact. Solar SMR and solar biomass gasification are the most promising for scalability. The essential conceptual message of this research lies in combined hydrogen production and concentrating solar power systems, which show that the mentioned systems can produce hydrogen with a solar-to-hydrogen efficiency reaching 45%. This efficiency is much higher than that of conventional electrolysis methods; this confirms the readiness of solar thermal processes as a viable solution for generating more hydrogen.