Direct coupling of H2 production through a high pressure PEM electrolyzer and its storage by physisorption on microporous materials

The paper describes a set of experimental tests carried out on an integrated system at the laboratory level comprising both a high pressure electrolysis system (up to 25 bar) coupled with H-2 physisorption apparatus on five commercially available adsorbents (two Metal Organic Frameworks, two activated carbons and the 13X zeolite). Description is given of the integrated system and results are reported, for each considered material, consisting in equilibrium H-2 adsorption/desorption isotherms at 77 K, measured in a static volumetric method. To determine the validity of the pathway adopted for the production and storage of hydrogen, in terms of energy costs, a comparison is carried out of the process energy balance with: (i) low pressure electrolysis and H-2 liquefaction; (ii) low pressure electrolysis and high pressure H-2 compression; (iii) electrolysis at 25 bar and physisorption storage. Both the experimental and energetic results are described and discussed.