The growing interest in hydrogen (H₂) has motivated process engineers and industrialists to investigate the potential of liquid hydrogen (LH₂) storage. LH₂ is an essential component in the H₂ supply chain. Many researchers have studied LH₂ storage from the perspective of tank structure, boil-off losses, insulation schemes, and storage conditions. A few review studies have also been published considering LH₂ storage; however, most are simply collections of previous articles. None of these review articles have critically evaluated the research articles. In this review study, recent reports, conceptual studies, and patents have been included and critically discussed. Further, challenges and recommendations have been listed based on the literature review. Our results suggest that the multi-layer insulation scheme and integrated refrigeration system can effectively reduce boil-off losses. However, boil-off losses from storage tanks during transportation are the least discussed and must be addressed. The cost of an LH₂ storage tank is high, but it can be reduced with advancements in materials and the utilization of latest technologies. The present challenges and future directions for LH₂ storage include minimizing and utilizing boil-off losses, improving insulation schemes, and ensuring cost-effective large-scale LH₂ storage. This review study can be fundamental for process engineers and new academic researchers to design energy-efficient and cost-effective LH₂ storage systems.

Blends of monoethanol amine (MEA) with an aqueous deep eutectic solvent (DES), with MEA present in various proportions of 5, 10, and 15 wt%, are used in process design for biogas upgrading.

Hydrogen (H₂) is known for its clean energy characteristics. Its separation and purification to produce high-purity H₂ is becoming essential to promoting a H₂ economy. There are several technologies, such as pressure swing adsorption, membrane, and cryogenic, which can be adopted to produce high-purity H₂; however, each standalone technology has its own pros and cons. Unlike standalone technology, the integration of technologies has shown significant potential for achieving high purity with a high recovery. In this study, a membrane–cryogenic process was integrated to separate H₂ via the desublimation of carbon dioxide. The proposed process was designed, simulated, and optimized in Aspen Hysys. The results showed that the H₂ was separated with a 99.99% purity. The energy analysis revealed a net-specific energy consumption of 2.37 kWh/kg. The exergy analysis showed that the membranes and multi-stream heat exchangers were major contributors to the exergy destruction. Furthermore, the calculated total capital investment of the proposed process was 816.2 m$. This proposed process could be beneficial for the development of a H₂ economy.