Carbon materials for hydrogen storage

The issue of hydrogen storage on carbon materials has opened up a big discussion and controversy. The Carbon Materials Technology Group at ORNL is currently undergoing a comprehensive study of several forms of carbon, from the very amorphous activated carbons to the very ordered forms such as graphite and nanostructured carbons. Hydrogen uptake measurements were performed in a gravimetric system at both room and cryogenic temperatures, and at pressures of up to 20 bar (∼300psi). It was found that carbon materials store very little hydrogen (<0.3 wt. %) at room temperature but considerable amounts of hydrogen at cryogenic temperatures. The ongoing effort is being focused on understanding the variables (carbon source, surface area, pore size, dopants, degree of crystallinity, etc) that affect hydrogen adsorption, and to tailor these properties to optimize the storage to achieve the current storage target established by the US Department of Energy.