Modulating the current in water electrolysis does not increase energy efficiency compared to a constant equal average current
Anamika Ghosh (TU Delft - Complex Fluid Processing)
J. W. Haverkort (TU Delft - Large Scale Energy Storage)
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Abstract
Modulating the potential or current amplitude can improve mass transfer and assist in the bubble removal of electrochemical processes. However, the impact on energy efficiency of water electrolysis requires careful assessment. This study examines an anion exchange membrane (AEM) electrolyser under pulsed and direct current (DC) operating conditions. Two cathode catalysts were tested using square pulses with a duty ratio of 0.5 and 0.9 across 0.005-500 Hz. The pulsed method consumes more or comparable energy compared to the DC case at a time-averaged current density of (Formula presented) (Formula presented) in 1 M KOH. Unlike most studies, we argue that a fair comparison can only be made at an equal average current density to ensure same hydrogen production rate. Using this metric, we find no evidence of any improvement under the tested conditions, highlighting the need for a more rigorous evaluation of the effectiveness of dynamic power strategies.
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