Coated silica shells: an advanced hydrogen storage system

We have investigated a new concept for the storage of hydrogen gas. It consists of storing hydrogen on a bed of small metal-coated spherical shells of nearly pure silica composition. The silica shells function as high pressure containers which because of silica's high strength, can withstand the pressures required to achieve significant gas storage densities. Since pure silica is too permeable to adequately retain hydrogen, a metal (e.g., Ni, Cu, Mo) coating is added as a room temperature permeation barrier. Fortunately, the rate at which hydrogen permeates these metals varies rapidly with temperature. Consequently, to cause the hydrogen to readily permeate the metal coating as well as the silica shell requires heating the bed to only moderate temperatures