Semi Empirical Modelling of Alkaline Water Electrolysis Green Hydrogen Using Biosynthesized Lye and Caustic Soda Electrolytes

Abstract

Semi empirical modelling of an alkaline water electrolysis system for green hydrogen production was carried out in this paper. Green hydrogen which is an alternative to fossil fuels and other sources of energy because of its renewability and sustainability is produced via alkaline water electrolysis utilizing biosynthesized lye (KOH) and caustic soda (NaOH) obtained from charring unripe plantain peel and electrolysing sea water respectively. The alkaline water electrolysis process was carried out at electrolyte concentrations of 25 g/L, 30 g/L and 35g/L for KOH and NaOH, at temperatures 45 oC, 55 oC, 65 oC, 75 oC and 85 oC, applying a voltage of 9 volts and running the electrolytic process for 15 minutes to obtain the volume of hydrogen generated at the cathode. The models developed were for the cell voltage of the energy consumed, the Faraday’s efficiency of the alkaline water electrolysis and the gas purity of the hydrogen produced. All R2 values which represent the coefficient of determination were within the range of 0.96-0.999, indicating that the semi empirical models were a good fit to represent the alkaline water electrolysis, with the exception with the cell voltage models at 30 g/L of KOH and 30 g/L NaOH which had an R2 values of 0.7826 and 0.782 respectively. Also, a pop and combustion test was carried out to determine the presence and flammability of hydrogen at the cathode of the electrolytic cell.