Dynamics of Hydrogen Storage through Adsorption: Process Simulation and Energy Analysis

The mass and energy balances of a zero-dimensional model for hydrogen storage by adsorption is studied. The model is solved with an in-house MATLAB code and validated with three experimental case studies from the literature, obtained with cryogenic lab-scale reservoirs using different adsorbents and dynamic operating conditions. The results of the simulations agree well with reported measured temperature and pressure profiles. The hydrogen adsorption process is described assuming instantaneous thermodynamic equilibrium. In accordance with the potential theory, variations in the adsorbed phase volumes filling the adsorbent pores were described applying the revisited Dubinin–Astakhov (rev-D-A) equation and accounting for gas phase non-ideality. The simulation model was used to assess the energy requirements of a variety of adsorption-based hydrogen storage processes and compared with other conventional hydrogen storage modes such as compression and liquefaction. Thus, whatever different adsorbent materials are considered, this technology appears relatively energy intensive due to the reservoir cooling duty at cryogenic temperature.