Material Storage for Hydrogen
The material storage of hydrogen involves the use of materials that can absorb and release hydrogen reversibly, often through processes such as absorption or adsorption. This method is being explored as an alternative to traditional storage methods like compressed gas or liquid hydrogen, offering potential advantages in terms of safety, weight, and ease of transport. Two primary approaches are commonly investigated for material storage of hydrogen:
1. Hydrogen Absorption/Adsorption
Metal Hydrides:
- Certain metals and alloys have the ability to form hydrides, where hydrogen is absorbed into the crystal lattice of the material.
- The process is reversible, allowing the release of hydrogen when needed.
- Examples include complex metal hydrides like sodium aluminum hydride and magnesium hydride.
Carbon-based Materials:
- Some carbon-based materials, such as activated carbon and carbon nanotubes, can adsorb hydrogen onto their surfaces.
- These materials have a high specific surface area, providing ample sites for hydrogen adsorption.
2. Chemical Hydrogen Storage
Liquid Organic Hydrogen Carriers (LOHC):
- Liquid organic compounds, such as certain organic oils or nitrogen-containing compounds, can chemically bond with hydrogen.
- The process involves releasing and retrieving hydrogen from the carrier substance, allowing for safe and reversible storage.
Ammonia (NH3):
- Ammonia is another chemical compound that can store and release hydrogen.
- Hydrogen is chemically bound to nitrogen in ammonia, and the release can be triggered when needed.
Key Features
Reversibility: Material storage methods are designed to be reversible, allowing for the absorption and release of hydrogen under controlled conditions.
Safety: Some material storage approaches offer potential safety advantages, as they can operate under milder conditions compared to high-pressure gas or cryogenic storage
Weight and Volume Efficiency: Material storage methods have the potential to be more weight and volume-efficient compared to traditional storage methods, making them suitable for various applications, including mobile and portable systems.
Temperature and Pressure Conditions: The conditions required for hydrogen release can vary depending on the specific material used. Some materials release hydrogen at moderate temperatures, while others may require higher temperatures or pressures.
Challenges
Storage Capacity: Achieving high hydrogen storage capacity is a significant challenge for many materials, and researchers are continually working to improve the performance of storage materials.
Kinetics: The kinetics of hydrogen absorption and release can be slow for some materials, affecting the efficiency and practicality of the storage system.
Cost: The cost of materials, especially those with desirable properties, can impact the economic viability of material storage systems.
Cycling Stability: The ability of materials to undergo repeated cycles of hydrogen absorption and release without significant degradation is crucial for practical applications.