Highly efficient advanced alkaline electrolyzer for solar operation

Since April 1989 an advanced 10 kW electrolyzer has been operated under solar conditions in the experimental test facility in Stuttgart. The specific energy consumption at 80°C, 250 mA cm−2 and ambient pressure is 3.84 kWh Nm−3 H2. This is a reduction of 15 % compared with conventional electrolyzers. At a current density of 25 mA cm−2, corresponding to 5 % of nominal load and a temperature of 60°C, a current efficiency of 75 % and a content of 2 % hydrogen in oxygen was measured. These values are in good agreement with presented numerical calculations. Up to now, no degradation of electrodes has been observed.