 Hydrogen has a wide range of chemical reactions and forms compounds with many different elements. These compounds often have interesting structures, compositions and properties. Metal hydrides are also becoming increasingly popular for their potential applications in energy storage. They can be used as batteries, electrodes and thermal storage materials, and they can even be combined with fuel cells to create a more efficient system. Additionally, these metal hydrides can be used to store solar heat more efficiently than traditional heat storage materials. This article was authored by Kasper T. Mahler, Drew Shepard, Dorfby Ravensbake and others.