How can calcium hydride serve as a portable source of hydrogen?

Calcium hydride (${\text{CaH}}_2$) is a saltlike, crystalline compound that serves as a convenient, portable source of hydrogen gas. Its utility as a hydrogen source stems from its chemical reactivity; when it reacts with water, it releases hydrogen gas efficiently. This property makes it a practical material for applications where hydrogen is needed on demand without the logistical challenges of transporting or storing large volumes of pressurized hydrogen gas.1

Beyond its role as a hydrogen source, calcium hydride is also utilized as a drying agent and as a reducing agent in the preparation of various powdered metals. While other types of hydrides, such as metallic or interstitial hydrides, are formed by transition metals absorbing hydrogen into their crystal lattices, calcium hydride is distinct in its saltlike nature and its specific application as a portable chemical reservoir for hydrogen.123