XQ -Hydrogen Alkaline Electrolyser Technology

Operation and Characteristics

As pointed out in the introduction, among the four existing water technologies,only two are available in the market such as alkaline, PEM; whereas SO and AEM are still being investigated before widespread acceptance and dissemination

In this review work, XQ alkaline water electrolysis technology is considered since it is currently being employed in many research projects such as the development of carbon-free hydrogen production facilities supplied by renewable sources Similar to fuel cells,electrolyzers performing the water electrolysis process are composed of an anode and a cathode separated by an electrolyte. In the case of the alkaline electrolyzer, the electrolyte is based on a liquid solution that may be potassium hydroxide (KOH) or sodium hydroxide (NaOH) . Generally, alkaline electrolyzer manufacturers prefer to use KOH instead of NaOH since an aqueous solution with 25–30 wt.% KOH features a higher specific electrolyte conductivity at a standard temperature range from 50 to 80 ◦C .

The principle of operation of the alkaline water electrolysis is provided in Figure 1; while the equations of the chemical reactions are given in Equations (1)–(3) below:
Anode : 2OH− → 1/2O2 + H2O + 2e
Cathode : 2H2O + 2e → H2 + 2OH−
Global : 2H2O → 2H2 + O2