Chemical and Metal Hydride Hydrogen Storage
Scientists in government, industry, and academia are working to improve the weight, volume, and cost of current hydrogen storage systems. The term "chemical hydrogen storage" is used to describe storage technologies in which (1) hydrogen is released from a material through a chemical reaction and (2) the hydrogen is restored through a chemical reaction when the material is being recharged. Common reactions involve heating chemical hydrides to release hydrogen and/or reacting chemical hydrides with water or alcohols. Various types of containers for materials suitable for chemical hydrogen storage are being investigate.
Metals that form hydrides can reversibly absorb and release hydrogen when appropriate temperatures and pressures are applied. For hydrogen fueling applications, these metal hydrides must be able to quickly and efficiently absorb and release hydrogen during the duty cycle. Work in metal hydrides includes new materials discovery, properties characterization, and engineered system development. The goals are safe and economically favorable metal hydride storage for hydrogen-powered devices. A potential benefit of chemical hydrogen storage is reduced need for high pressure which may reduce the cost and complexity of hydrogen fueling equipment and allow for conformable storage containers for improved packaging.
Typically, recharging materials in containers is not easily done with the storage container connected to the hydrogen-using device. Hence, the spent fuel container is generally removed from the device and regenerated elsewhere.
In 2021, chemical and metal hydride hydrogen storage is not in use for larger devices like passenger vehicles and industrial trucks, but there are some applications for smaller devices like scooters and handheld devices.
For a longer discussion about these two technologies, see: