Chemical Energy Storage Based on Nanoporous Aluminum
Tech ID: 25354 / UC Case 2016-047-0
Researchers in the Department of Chemistry and Biochemistry at UCLA have developed a novel form of nanoporous aluminum hydride for storing hydrogen at room temperature and pressure.
Hydrogen is an attractive source of fuel as it has one of the highest gravimetric energy densities (three times greater than petroleum), while at the same time only producing water as a byproduct of combustion. However, implementing hydrogen as a fuel has been difficult due to storage issues. Because hydrogen is a gas at room temperature and pressure, it must be compressed into pressurized gas or liquid for efficient storage. Unfortunately, this pressurized state is highly flammable and thus creates safety concerns. Alternatively, solid-state hydrogen storage increases the volumetric hydrogen storage density and provides stability to the storage system. Metal hydrides provide sufficient hydrogen storage densities to meet the DOE’s guidelines. Commercially available metal hydride materials such as the AB-5 type alloy have a gravimetric hydrogen storage density of 1.5 wt.%, which is currently below the DOE’s 2017 guideline of 5.5 wt. %. Aluminum hydride has a gravimetric hydrogen storage density of 10.1 wt. %, which is significantly higher than the DOE’s guidelines as well as what is commercially available. Porous or nanoporous materials are ideal as the host metal structure, since most of the chemical reactions involved in hydrogen storage occur at the surface, and the porous nature reduces the weight of the fuel cell. Unfortunately, storing molecular hydrogen is aluminum requires impractical pressures or expensive chemical synthesis. Therefore, there is a need for a reversible hydrogen storage mechanism that can operate at atmospheric pressure and practical temperatures.
Researchers in the Department of Chemistry and Biochemistry at UCLA have recently developed a novel technique of storing hydrogen in the form of nanoporous aluminum hydride at room temperature and pressure. The novel nanostructured fabrication technique provides a BET specific surface area of ~220 m2/g, roughly an order of magnitude greater than reported existing nanoporous metals. The hydrogen can be released in a reversible process at 100°C, restoring the nanoporous aluminum for further use. This technique paves the way for incorporating aluminum hydride as a hydrogen storage material in a practical and safe manner.
- Hydrogen incorporation at room temperature and atmospheric pressure
- Four times greater gravimetric hydrogen storage density compared to commercial materials
- An order on magnitude greater BET specific surface area (~220 m2/g)
State Of Development
The nanostructured aluminum material has been fabricated and characterized.
|United States Of America