Hydrogen Storage Technologies

Hydrogen storage is one of the main issues hindering the spread of fuel cell-based applications and, more generally, the advent of the so-called "hydrogen economy." On the one hand, classical gas compression and liquefaction systems provide a rela- tively efficient and consolidated approach, but involve enormous security problems, and compression and refrigeration costs are high. On the other hand, there are sev- eral alternative approaches to hydrogen storage, essentially based on hydrogen che- misorption or physisorption processes on various support materials. In this chapter, an overview is presented of a proposed large and interesting class of materials, the carbonaceous materials, which are attractive candidates for hydrogen storage due to a combination of adsorption ability, high specific surface area, pore microstructure, and low-mass density. In general, it is possible to distinguish: a) materials consisting only of carbon atoms (carbon nanofibers, single- and multi-walled nanotubes, etc.); b) materials containing carbon and other light elements (polyaniline, polypyrrole, etc.); c) composite materials made by polymeric matrix (hyperbranched poly(amide- amine) with vanadium oxide, metal oxide anchored to a polyetheretherketone matrix, etc.); d) waste and natural materials (coconut flesh, coffee bean wastes, etc.).