Large-scale storage options for compressed hydrogen – pv magazine International
Finnish and Swedish researchers have looked at different ways to store compressed hydrogen gas, including storage tanks, geological storage and other underground options.
A Swedish-Finnish research group conducted a comprehensive analysis of all storage options for large-scale compressed hydrogen, including storage vessels, geological storage and other underground options.
They complemented their qualitative review with an assessment that considered a wide range of technological advances for storing compressed hydrogen gas.
“Most of the technologies discussed in this study are immature and under development, which means research is still ongoing,” they said. “Additionally, the infrastructure and facilities behind some of the technologies are massive, which would require significant resources and costs.”
They also noted that storage projects should be large enough to ensure low cost and profitability.
“The smaller the size, the more expensive and impractical the option would be. Moreover, the geological nature and viability are crucial factors for certain technologies,” they warned, referring to the constraints of geological options.
Storage tanks
Scientists have grouped storage vessels into four categories: pressure vessels made of metals such as carbon steel and low-alloy steel, load-bearing thick metal jackets made of steel or aluminum, metal jackets thin with fiber resin composites, ultra-thin metal jackets fully shrouded with fiber resin composites and unlined fully composite pressure vessels based on fiber reinforced shells.
Scientists have noted the importance of different components such as valves, sensors and storage containers for this type of hydrogen storage. They also considered the fiber-reinforced composites most commonly used for hydrogen storage tanks, including carbon fiber, fiberglass, and fiberglass. They also looked at polyester, phenol and epoxy resins for the manufacture of pressure vessels. They stated that the latter are the best candidates due to their high mechanical properties and resistance to temperature and corrosion.
They also looked at seamless hydrogen storage tanks at hydrogen filling stations and multifunctional layered fixed hydrogen storage tanks. The former can be cascaded in multi-vessel assemblies via valves and interconnecting piping manifolds, resulting in more hydrogen leak points. The latter are considered ideal for large-scale hydrogen storage operating at high pressure, without size restrictions. Scientists also looked at composite steel-concrete pressure vessels and metal containers for natural gas.
Geological storage
The Swedish-Finnish group evaluated several options for the geological storage of hydrogen, including depleted oil and gas reservoirs, aquifers, salt caverns, abandoned mines and rock caverns.
“The geological storage system generally includes injection and withdrawal wells and a containment layer. Injection and withdrawal wells are the devices responsible for moving hydrogen in and out of underground geological formations,” they said.
In addition, they assessed the viability of hydrogen blending in gas pipelines and underground methanization reactors.
“Despite the advantages of injecting hydrogen into the natural gas grid, there are also disadvantages that limit the amount of hydrogen (%) that can be injected. Hydrogen embrittlement is one of the main issues regarding pipeline safety and the risk of leakage,” the scientists said, referring to the first of the two technologies.
They see methanisation reactors as a potentially interesting alternative, but they are still worried about the rate of methane production.
“The resulting methane could then be added to the natural gas grid, which can provide large storage accessible by renewable sources close to the natural gas grid,” they said.
The academics said they ultimately want to conduct remote assessments for hydrogen transport, storage losses and all uses of stored hydrogen.
“Knowing these factors will help decision makers analyze and identify trade-offs between different factors regarding different technologies based on case-by-case requirements that may include specific technical parameters such as throughput or storage size” , they said.
They presented their findings in “Large-scale compressed hydrogen storage as part of renewable electricity storage systemswhich was recently published in the International Journal of Hydrogen Energy. The research group includes scholars from KTH Royal Institute of Technology in Sweden and Aalto University in Finland.
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