Volumetric hydrogen density

Miller, A., Hess, K., and Barnes, D. (2003). Comparison of Practical Hydrogen Storage Volumetric Densities, DE-FC36-99GO10458. 

Apart from the above-mentioned commercial impasse, which delays the development of the hydrogen economy, there are two important technical issues that also need to be solved hydrogen s volumetric density and energy consumption during hydrogen production. 

The most established storage systems are high-pressure gas cylinders with a maximum pressure of 20 MPa. New lightweight composite cylinders have been developed that are able to withstand pressures up to 80 MPa and so the hydrogen can reach a volumetric density of 36 kg m, approximately half that in its liquid form at the normal boiling point. 

The volumetric density of hydrogen in a pressure vessel increases with pressure and reaches a maximum above 1000 bar, depending on the tensile strength of the material. However, the gravimetric hydrogen density of the pressure cylinder... 

Figure 5.5 Volumetric density of compressed hydrogen gas as a function of gas pressure including the ideal gas and liquid hydrogen. The ratio of the wall thickness to the outer diameter of the pressure cylinder is shown on the right-hand side for steel with a tensile strength of 460 MPa. A schematic drawing of the pressure cylinder is shown as an inset.

Figure 5.7 Volumetric and gravimetric hydrogen storage density for pressurized gas. Steel (tensile strength Gv = 460MPa, density 6500 kg m ) and a hypothetical composite material (cJv— 1500 MPa, density 3000 kg m ). The circles represent pressure cylinders from Dynetek.

Glass microspheres offer only a limited volumetric hydrogen storage density of less than 20 kg m [9]. Furthermore, a glass sphere with the pressurized system is not in equilibrium and only kinetically hindered in diffusion. 

The rapid kinetics of Reaction 1, the high volumetric hydrogen storage densities, and the wide range of hydrogen decomposition pressures of the AB5 hydrides initiated proposals to use them as chemical compressors, cryogenic... 

Higher storage densities are possible with liquid hydrogen the density at 2 bar is 67.67 kg m . The physical limit of the volumetric energy density at 2 bar is thus 2.3 kWhdm for pure hydrogen. However its very low boiling point at -253 °C... 

Because of their high volumetric density, intermetallic hydrides are also used as hydrogen storage materials in advanced fuel cell driven submarines, prototype passenger ships, forklifts and hydrogen automobiles as well as auxiliary power units for laptops. 

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