Abstract

Hydrogen is an energy carrier that is used in a wide variety of applications, including generation of a clean energy by fuel cells and as a fuel in vehicles. This leads to mitigating the negative impacts of utilizing fossil fuels in such applications. Water electrolysers are crucial devices for hydrogen production. However, they suffer from low rate of gas evolution and high energy consumption. In this paper, in order to tackle these two issues, we propose 316L stainless steel electrodes – which we created - with a triangle shape topology for alkaline water electrolysers. The electrodes’ triangle topology is formed using electroerosion that allowed obtaining an average surface roughness of 12.6 μm. The performance of the proposed electrolyzer is investigated with six different values of the distance between electrodes, namely 8.2, 6.05, 5.4, 4.2, 3.7 and 1.6 mm at two values of operating temperature (20.1 and 30 °C). The obtained polarization curves per unit area (current density versus applied voltage) show that as the distance between electrodes is decreased, the current density increases due to the decrease in the electrical resistance. A higher current density implies a greater quantity of the formed product. Thus, using the same amount of energy, a greater volume of hydrogen is obtained. The results of investigating the effect of the operating temperature on the electrolyser’s performance disclose that – contrary to the effect of the distance between electrodes - the current density increases with the increase in the operating temperature, yielding a higher rate of hydrogen evolution. Moreover, the results revel that the optimal performance of the electrolyser - when considering the combined effect the operating temperature and the distance between electrodes - is achieved: i) at a distance of 2.6 mm and an operating temperature of 30 °C; and ii) at a distance of 1.6 mm between electrodes and 20.1 °C operating temperature.

Key words: Alkaline water electrolyser; Triangle shape topology; Electrodes; Hydrogen; Energy