The State of the Art in Hydrogen Storage

The global renewable energy mix is set to change even further with the increasing demand for hydrogen. Hydrogen production levels are dramatically increasing, and it is becoming prevalent that the storage of hydrogen gas is much more complex than natural gas. There are many different hydrogen storage options being investigated, trialed, and used within the energy industry. On-land storage of hydrogen uses compressed pressure vessels for gas, cryogenic storage for liquid hydrogen, and the blending of hydrogen into natural gas to be stored in current pipeline systems. Underground storage options are found in depleted hydrocarbon reservoirs, deep aquifers, and salt caverns. The storage of hydrogen gas presents numerous challenges and opportunities as discussed in this paper, such as design and manufacturing, hydrogen embrittlement and behavior, structural integrity, standards and regulation, safety of high-pressure storage, subsea storage, and circular economy prospects in structural design. Various vessel compositions have been extensively explored to find the most suitable material combinations for pressure vessel designs, with Type IV being the most commonly used. However, significant opportunities remain to enhance vessel designs for more efficient hydrogen storage. Advancements could include improvements in storage efficiency, innovations in subsea and underground storage, and designs aligned with circular economy principles.