Experimental Investigation of two low-cost 5 kW alkaline electrolyzer prototypes' performances depending on size and applied voltage

In light of the energy transition, developing efficient and scalable hydrogen production technologies is essential for reducing greenhouse gas emissions and meeting global energy needs. Studying the electrical performance of electrolyzers, this study examines the effect of various parameters such as surface area, electrolyte concentration, temperature, and applied voltage on hydrogen production and efficiency. The experimental setup involved the evaluation of five electrolyzer stacks with surface areas of both 400 cm2 and 825 cm2. The electrolytes were the NaOH aqueous solutions with mass concentrations of 1 wt%, 3 wt%, and 5 wt%. At the same time, the cell voltage varied between 10 V and 15 V. For the 400 cm2 stack, a 1 kW power output was achieved at a 5 wt% electrolyte concentration and a voltage range of 13 V–15 V. The 825 cm2 stack also reached a similar power output, but at a lower concentration of 4 wt%. At higher electrolyte concentrations, the 400 cm2 stack outperformed the 825 cm2 stack in terms of current density. With 0.181 A/cm2 at 15 V and 5 wt%, it exceeded the 0.1 A/cm2 benchmark for efficient operation. According to temperature analysis, the temperature increased linearly to 60 °C before approaching 90 °C asymptotically. To prevent boiling and possible system damage, safety procedures were put in place to cease operation at 85 °C. Concerning hydrogen production, the 400 cm2 stacks showed a linearly increasing volumetric flow rate with voltage and NaOH concentration, reaching a maximum of 5 SLPM at 15 V and 5 wt%. These findings carry crucial implications for the design of more efficient and cost-effective electrolyzers for industrial hydrogen production.