Hydrogen Energy Storage Methods, Efficiency, Cost, Pros and Cons
Hydrogen energy storage is the act and process whereby hydrogen is contained effectively and safely as an energy resource.
This article discusses hydrogen energy storage methods, efficiency, cost, advantages and problems, as outlined below;
-Hydrogen Energy Storage Methods
-Hydrogen Energy Storage Efficiency
-Hydrogen Energy Storage Advantages
-Hydrogen Energy Storage Problems
Hydrogen Energy Storage Methods
Hydrogen energy storage methods are; physical, chemical, automotive, and stationary.
1). Physical Storage (as one of the Hydrogen Energy Storage Methods)
Physical hydrogen energy storage includes all techniques or methods that actively utilize the physical characteristics of hydrogen, to stabilize it as an energy storage medium.
In physical storage, there is usually no notable change in the chemical composition or attributes of hydrogen. Rather, it is converted from one physical state to another, to keep it in a state of equilibrium whereby it can be safely and effectively contained and transported.
Criteria that are important for physical hydrogen energy storage are temperature and pressure. Effective compression and storage of liquid hydrogen is possible under cryogenic and high-pressure conditions (-252.8°C and 5,000-10,000 psi for temperature and pressure respectively) [3].
Aside cryogenic compression, physical storage of hydrogen energy is achievable using porous media like layered carbon, zeolites, glass capillary arrays, carbon nanotubes, and glass microspheres.
2). Chemical Hydrogen Energy Storage
Chemical storage method for hydrogen energy involves chemical reactions that convert hydrogen to a form in which it is both stable and easily recoverable.
This includes the assimilation of hydrogen into metals, ammonia, carbohydrates, and organic compounds.
Examples of compounds and mechanisms used for chemical hydrogen energy storage are;
1). Metal hydrides
2). Carbon dioxide hydrogenation
3). Formic acid
4). Aluminum
5). N-Heterocycles
6). Ammonia
7). Organic hydrogen carriers
8). Carbohydrates
9). Amine boranes
3). Automotive Hydrogen Energy Storage (as one of the Hydrogen Energy Storage Methods)
Automotive hydrogen energy storage refers to the use of fuel cells designed to safely contain hydrogen fuel in hybrid cars, jets and spacecrafts among other hydrogen-dependent automobile systems.
It is often based on the same principles behind physical hydrogen energy storage.
4). Stationary Hydrogen Energy Storage
Stationary hydrogen energy storage is a method whose effectiveness directly depends on the stationary state of equipment used for the containment of hydrogen fuel.
Here, the stability of stored hydrogen is generally at risk of disruption if any significant motion occurs.
Examples of stationary hydrogen storage are; underground storage, stationary compressed storage, and stationary compressed-cryogenic storage.
Hydrogen Energy Storage Efficiency
Hydrogen is a good energy storage medium in terms of efficiency.
Factors that contribute to this include hydrogen energy density; which is up to three times that of gasoline at about 120MJ/kg [1]; and low volumetric density of hydrogen. These attributes imply that large amounts of energy can be stored within a relatively small volume when hydrogen is compressed under suitable conditions.
Hydrogen energy storage efficiency ranges between 30-70%, and varies with method of storage.
When viewed as an energy storage system, the efficiency and capacity of hydrogen may exceed that of other storage systems like batteries. It may also be considered a more economic medium of energy storage.
Hydrogen Energy Storage Cost
Hydrogen energy storage cost ranges from $15-20/kWh [4].
This range can be attributed to the nature of equipment and conditions required for hydrogen energy storage, which include; high pressure and low temperature apparatus.
The cost of hydrogen energy storage for any given scenario is influenced by the method and equipment used, which are directly linked to the amount of energy consumed in the process of storage.
Hydrogen Energy Storage Advantages
Hydrogen energy storage advantages are;
1). High efficiency
2). Fair performance of hydrogen as an energy storage medium
3). Relevance toward sustainable development, energy transition and green economy-building
4). Potential mitigation of greenhouse emissions
5). Higher energy density of hydrogen storage than fossil fuels
Hydrogen Energy Storage Problems
Hydrogen energy storage problems are;
1). Expensive storage equipment
2). High energy-demand of storage process
3). Long-term storage is possible, but requires maintenance and monitoring
4). Low volumetric density means that minor leakages can lead to instantaneous, large losses
5). Hydrogen energy is not always green
6). Storage technologies and techniques for hydrogen energy are not fully developed and have practical limitations
Major challenges with hydrogen storage are based on two factors; the conditions required for storage and the possible environmental impacts of unsustainable storage.
When hydrogen is described as a renewable fuel and hydrogen energy as a form of renewable energy, holistic consideration of the sources, production and storage methods, must be made.
This is because of the difference between the states of being renewable, green, and sustainable [2].
Hydrogen energy and its storage are only fully sustainable and safe for the ecosystem when hydrogen comes from renewable primary sources like biomass or water, and is both extracted and stored with clean energy-powered equipment/processes.
Conclusion
Hydrogen energy storage refers to the provision of suitable equipment and mechanisms for effective and efficient containment of hydrogen fuel.
Hydrogen energy storage methods are;
1. Physical Storage
2. Chemical Hydrogen Energy Storage
3. Automotive Hydrogen Energy Storage
4. Stationary Hydrogen Energy Storage
Hydrogen energy storage efficiency ranges from 30-70%.
The cost of hydrogen energy storage cost ranges from $15-20/kWh.
Hydrogen energy storage advantages are; high efficiency, fair performance, relevance toward sustainable development, emission mitigation, and high energy density.
Hydrogen energy storage problems are; cost, energy-demand, maintenance requirement, leakage and loss risks, possible un-sustainability, and immature technology.
References
1). Aziz, M.; Wijatanta, A. T.; Nandiyanto, A. (2020). "Ammonia as Effective Hydrogen Storage: A Review on Production, Storage and Utilization." Energies 13(12):3062. Available at: https://doi.org/10.3390/en13123062. (Accessed 10 January 2023).
2). Iscrupe, L. (2022). "Green Energy." Available at: https://www.saveonenergy.com/green-energy/. (Accessed 10 January 2023).
3). Prachi, P. R.; Mahesh, W. M.; Aneesh, G. C. (2016). "Review on Solid State Hydrogen Storage Material." Available at: https://doi.org/10.13189/aep.2016.040202. (Accessed 12 January 2023).
4). Schoenung, S. M.; Susan, M. (2011). "Economic analysis of large-scale hydrogen storage for renewable utility applications." Available at: https://doi.org/10.2172/1029796. (Accessed 10 January 2023).
