High-pressure electrolysis

Abstract

High-pressure electrolysis (also called high-pressure electrolysis HPE) is the water electrolysis performed at pressures higher than ambient in which electrical energy is the driving force of the water decomposition to produce oxygen (O2) and hydrogen (H2). The core of an electrolysis unit is an electrochemical cell, which is filled with pure water and has two electrodes connected with an external power supply. Electric current causes positively charged hydrogen ions to migrate to the negatively charged cathode, where a reduction takes place in order to form hydrogen atoms. The atoms formed then combine to form gaseous hydrogen molecules (Eq. 1). On the other hand, oxygen is formed at the other electrode (the positively charged anode) (Eq. 2). The amount of gases produced per unit time is directly related to the current that passes through the electrochemical cell (Wendt and Kreysa 1999)