Experimental Study on a Metal Hydride Tank for the Totalized Hydrogen Energy Utilization System

We have been performing research on a Totalized Hydrogen Energy Utilization System (THEUS) which is composed of a Unitized Reversible Fuel Cell (URFC) and metal hydride tanks. THEUS is very similar to the regenerative fuel cell system located at the Savannah River National Laboratory (SRNL) but it utilizes the thermal energy from the system to improve the total system efficiency. AIST and SRNL started a collaborative research program on THEUS in 2010 under the Clean Energy Partnership Technology Program between METI and DOE. To initiate the project, a horizontal type metal hydride tank was developed. It had a double coil type heat exchanger and contained 50 kg of AB5 type metal hydride alloy. Absorption and desorption of 6,350 NL of hydrogen was successfully attained at an absorption rate of 11.8 NL/min and a desorption rate of 8.1 NL/min. The experimental results of the heat exchanging performance were compared with the results of a vertical type metal hydride tank which was developed in AIST in 2008. This paper introduces the experimental results of the metal hydride tank which is tested in SRNL.