Evaluation of an Activated Carbon as an Adsorbent in Hybrid High Pressure Hydrogen Storage Tanks

Leighton Holyfield, Nuno Bimbo, Valeska Ting, Andrew Burrows, Tim Mays

Research output: Contribution to conferencePoster


Due to well documented issues with the use of fossil fuels, which contribute to anthropogenic climate change, the search for alternative energy vectors has been intensified lately. In recent years, hydrogen has generated great interest, due to its high gravimetric energy density and its potential production from water. However, storing hydrogen has proven troublesome, due to its very low volumetric energy density at ambient pressures and temperatures. As an aid to guide the development of new materials, the United States Department of Energy (DOE) has released targets for system gravimetric and volumetric densities, as well as other requirements, including cost. [1]. Hydrogen compression and liquefaction, the current state of the art technologies, have severe energy penalties and safety concerns, due to either high pressures (70 MPa) or low temperatures (20 K). One interesting alternative is the physisorption of hydrogen onto porous materials, which shows promise to store hydrogen at good volumetric densities under reasonable temperature and pressure conditions.

This work consists of the characterisation of AX-21 activated carbon, a commercially available microporous material, by measuring hydrogen isotherms between 77 - 298 K and at pressures between 0 – 20 MPa. The adsorbate density (assumed to be constant and different from the bulk density), pore volume and isosteric heat of enthalpy were estimated for the material by parameter fitting to a model developed previously [2]. The amount of hydrogen stored in a tank was then calculated by using the parameter values, and the volumetric density was calculated using a methodology that takes into account the filling ratio of the adsorbent [3]. These results were then compared to room temperature compression and it was found that the presence of the adsorbent was detrimental to the storage performance when operated at room temperature at temperatures above 150 K. This study facilitates the comparison between a hybrid high pressure tank and current conventional techniques, and identifies the engineering properties of a hybrid system that would meet the 5 kg DOE target for a tank for vehicular use.
Original languageEnglish
Publication statusUnpublished - 2014
EventH2FC: Hydrogen & Fuel Cell SUPERGEN Researcher Conference - University of Birmingham, Birmingham, UK United Kingdom
Duration: 15 Dec 201417 Dec 2014


ConferenceH2FC: Hydrogen & Fuel Cell SUPERGEN Researcher Conference
Country/TerritoryUK United Kingdom


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