Modeling of adsorption storage of hydrogen on activated carbons

The storage of hydrogen on board vehicles is one of the most critical issues for the transition towards an hydrogen-based transportation system. An electric vehicle powered by a typical gasoline tank will require 3.1 kg of hydrogen (H₂) to achieve a range of 500 km. Compared to a typical gasoline tank, this would correspond to a hydrogen density of 65 kg/m³ (including the storage system) and 6.5 wt%. Presently, only liquid hydrogen (LH₂) systems with a density of 51 kg/m³ and 14 wt% is close to this target. However, LH₂ is costly and requires more complex refueling systems. The physical adsorption of hydrogen on activated carbon can reduce the pressure required to store compressed gases. Though an efficient adsorption-based storage system for vehicular use of natural gas can be achieved at room temperature, the application of this technology to hydrogen using activated carbon as the adsorbent requires its operation at cryogenic temperature. We present the results of a parametric and comparative study of adsorption and compressed gas storage of hydrogen as a function of temperature, pressure and adsorbent properties. In particular, the isothermal hydrogen storage and net storage densities for passive and active storage systems operating at 77, 150 and 293 K are compared and discussed.