A Comprehensive Review of Liquid Organic Hydrogen Carriers: Typology, Energy Efficiency, Life Cycle Assessment, and Techno-Economic Analyses

This paper presents a holistic review of Liquid Organic Hydrogen Carriers (LOHCs), focusing on typology, energy efficiency, techno-economic analyses (TEAs), and life cycle assessments (LCAs). Initially, the study categorizes various LOHC systems documented in existing literature, outlining their chemical structures, catalysts, properties, and main applications. This survey aims to provide a comprehensive understanding of LOHC varieties, making it easier to compare across different types. Next, we explore the efficiency of LOHC systems by reviewing hydrogenation and dehydrogenation energy requirements, catalyst behavior, heat-management constraints, product-separation needs, and net energy storage capabilities. This review also includes reaction stoichiometries, recent catalyst and reactor developments, catalyst-deactivation mechanisms, and heat-integration options for high-temperature dehydrogenation. Finally, our investigation offers a detailed evaluation of TEA and LCA for LOHC systems found in the literature. By exploring economic feasibility and environmental impact, this study presents a complete picture of the sustainability of LOHC deployment. It includes assessments of life-cycle carbon emissions, levelized cost, supply-chain configuration, carrier recyclability, infrastructure compatibility, renewable-electricity capacity factors, and heat-recovery assumptions. Our findings aim to contribute to hydrogen storage and transport research by identifying the most important technical, economic, and environmental trade-offs for LOHC systems. By addressing gaps in recent literature, TEA comparability, and LCA coverage, this paper seeks to advance the development of LOHC technologies and support their broader adoption in a green and sustainable energy landscape.