HyPerComp Engineering Inc. (HEI) and Concurrent Technologies Corporation (CTC) have demonstrated a Type-II (steel liner) composite overwrapped pressure vessel (COPV) for off-board storage of compressed hydrogen gas.  A computational program was developed to explore the effects raw materials, tank geometry and pressure have on storage tank purchased capital cost ($/kg of H₂ stored), volumetric efficiency (kg H₂/liter of storage volume) and weight efficiency (H₂ capacity to tank weight ratio).  Based partly upon the results of this optimization program, a Type-II COPV utilizing a steel liner and carbon composite overwrap was selected as the most cost-efficient tank design.  The 6,700 psi service pressure COPV demonstrated a storage tank purchased capital cost of $641 per kg of hydrogen stored.  By comparison, the Department of Energy’s (DOE’s) cost targets for off-board compressed hydrogen gas storage are $500 and $300 per kg of hydrogen stored by 2010 and 2015, respectively.  Although the nature of the Type-II COPV does not lend itself to optimum weight efficiency, the volumetric capacity approaches the DOE target of 0.030.

This presentation shows the data obtained from this COPV development, including burst data, fatigue cycle testing data and data obtained from drop/impact testing followed by fatigue cycle testing.  The results of the computational study as well as the demonstrated COPV volumetric and weight efficiencies are also presented.