Novel Hydrogen Production and Power Generation System Using Ni-Metal Hydride Battery

Monday, 27 July 2015
Hall 2 (Scottish Exhibition and Conference Centre)
B. Choi, D. Panthi (The University of Tokyo), M. Nakoji, T. Kabutomori, K. Tsutsumi (Exergy Power Systems, Inc.), and A. Tsutsumi (The University of Tokyo)
We proposed a novel electrochemical system for hydrogen production and power generation based on a fuel cell/battery system. The reactions (hydrogen evolution and oxidation) in the system occur at solid/liquid and solid/gas two-phase boundaries. From a theoretical analysis of the energy efficiency, we found that this novel electrochemical reactor has high energy efficiency for both hydrogen production and power generation. Following the theoretical analysis, electrochemical charge/discharge performance characteristics were studied at various current densities by fabricating an experimental cell, which was composed of negative and positive electrodes with a 1:3 capacity ratio. From the experimental results, we found that hydrogen gas was produced in a linear manner during the charge process and it was completely consumed during the discharge process. The energy conversion efficiency of the hydrogen production and the round-trip efficiency of hydrogen production and power generation at a current density of 37.0 A/m2 were 98.3% and 79.6%, respectively. These results indicated that the present system is highly efficient compared with the conventional water electrolysis and/or power generation systems.