Recent challenges and development of technical and technoeconomic aspects for hydrogen storage, insights at different scales; A state of art review

The importance of the energy transition and the role of green hydrogen in facilitating this transition cannot be denied. Therefore, it is crucial to pay close attention to and thoroughly understand hydrogen storage, which is a critical aspect of the hydrogen supply chain. In this comprehensive review paper, we have undertaken the task of categorising and evaluating various hydrogen storage technologies across three different scales. These scales include small-scale and laboratory-based methods such as metal-based hydrides, physical adsorbents, and liquid organic hydrogen carriers. Also, we explore medium and large-scale approaches like compressed gaseous hydrogen, liquid cryogenic hydrogen, and cryocompressed hydrogen. Lastly, we delve into very large-scale options such as salt caverns, aquifers, depleted gas/oil reservoirs, abandoned mines, and hard rock caverns. We have thoroughly examined each storage technology from technical and maturity perspectives, as well as considering its techno-economic viability. It is worth noting that development has been ongoing for each storage mechanism; however, numerous technical and economic challenges persist in most areas. Particularly, the cost per kilogramme of hydrogen for most current technologies demands careful consideration. It is recommended that small-scale hydrogen storage technologies such as metal hydrides (e.g., MgH2, LiBH4) need ongoing research to enhance their performance. Physical adsorbents have limited capacity except for activated carbon. Some liquid organic hydrogen carriers (LCOHs) are suitable for medium-scale storage in the near term. Ammonia-borane (AB), with its high gravimetric and volumetric properties, is a promising choice for medium-scale storage, pending effective dehydrogenation. It shows potential as a hydrogen carrier due to its high storage capacity, stability, and solubility, surpassing DOE targets for storage capabilities. Medium-scale storage, utilising compressed gas cylinders and advancements in liquefied and cryocompressed hydrogen storage, requires cost reduction measures, and a strategic supply chain. Large-scale storage options include salt caverns, aquifers, and depleted gas/oil reservoirs, with salt caverns offering pure hydrogen, need further techno-economic analysis and deployment projects to mature, but storage costs are reasonable, ranging mostly from €0.25/kg to €1.5/kg for location specific large-scale options.