At the present time, hydrogen has become an essential element for many different industries, including the automotive sector, which is forward to developing new sustainable alternatives through zero-emissions vehicles. In such a context, the issue of hydrogen storage (and liquid hydrogen storage in particular) remains at the center of the current preoccupations around this element.
Today, many industries will have to resort to liquid hydrogen storage in order to use this element’s potential. However, this element’s characteristics (for instance, it being the lightest gas in the Universe), mean there are different challenges to be met when installing any liquid hydrogen container.
Why would you need liquid hydrogen storage?
Liquid hydrogen storage plays an essential part enabling companies to use this element. Throughout many industries, hydrogen is being used to enable different processes:
- Helps storing energy produced by renewables, which is often intermittent
- Works as rocket fuel for combustion in the space industry, including nuclear-powered rockets
- Provides decarbonized alternatives for domestic heating
- Plays a part in the metallurgical industry, where it prevents oxidation and reduces metal oxides
- Raw material for chemical processes, including the manufacture of plastics (polyethylene and polypropylene)
All these processes can only take place once safe and optimized liquid hydrogen storage is achieved.
Solid hydrogen and compressed hydrogen vs liquid hydrogen
Hydrogen presents a low ambient temperature density, which results in a low energy per unit volume. This is the reason why hydrogen storage methods must present higher energy density.
Taking this into account, there are at least three possible storage solutions for the issue of hydrogen storage:
1. Storing hydrogen under pressure
Storage of hydrogen as a gas requires high-pressure tanks that can range from 350–700 bar tank pressure (5,000 – 10,000 psi). This way, a higher storage density is achieved and thus, volume is reduced.
At the moment, this is the preferred method for some car manufacturers using hydrogen as fuel, as it allows storing enough hydrogen to cover between 500 – 600 km. However, this process also includes some disadvantages, including the need for a big space for this type of tanks or the danger in the refuelling process because of the high pressure.
2. Solid hydrogen
Hydrogen can also be stored using solid elements, both on the surfaces of solids or within them. In the first case, this is done through adsorption; the second case is done through absorption. This allows for safe storage, as a bond is created between the two elements that allows for any potential leaks to be at a slow rate, minimizing the risk of explosions.
3. Cryogenic liquid hydrogen storage
Liquid hydrogen storage requires cryogenic temperatures, as the boiling point for hydrogen is −252.8°C at atmospheric pressure. Just like high-pressure storage, some car manufacturers have opted for cryogenic liquid hydrogen storage, and it’s also the preferred choice for the space industry, as well as bulk in transportation. Even so, liquid hydrogen faces challenges in the huge energy consumption that occurs during liquefaction and in the loss of H2 through boil-off during storage.
Hydrogen storage: the challenges
Liquid hydrogen storage has been a challenge for many industries, as the maintaining of liquifying conditions requires a significant amount of energy.
In order to guarantee a safe hydrogen storage, companies must take several factors into account:
- Tests must be undertaken in order to guarantee that all equipment, from tanks to bottles, is capable of enduring real-life conditions for safe storage. At the same time, bottle control technologies allow companies to monitor the state of equipment and detect any possible problems, such as microcracks, that could develop into safety issues (as another challenge for liquid hydrogen storage is that hydrogen migrates quickly through small openings).
- Liquid hydrogen storage equipment must be designed to endure cryogenic (extremely low) temperature operations. This includes complying with all codes and regulations that modulate this type of system.
- Flammability: hydrogen presents a wide flammability range (4 – 7%) and a very small amount of energy is required for its ignition. In order to avoid any accidents, those in charge of installing any liquid hydrogen storage tank must take the necessary precautions.
Among our services, we provide repair and maintenance services for cryogenic equipment, distribute the products of the industry’s most well-known brands, and supply our own products for the transportation and storage of liquid gas.
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