Developments in advanced alkaline water electrolysis

Abstract Two parallel alkaline water electrolysis programs are underway at the Noranda Research Centre. One of these is part of Canada's contribution to the International Energy Agency (IEA) hydrogen program. Its objective is the evaluation of new anode, cathode and separator materials on an industrially-significant scale. Porous Teflon cloth impregnated with potassium titanate is shown to have the lowest resistance factor of the separators tested, but its fragility and hydrophobicity are of concern. Felted polysulfone has shown the robustness, gas tightness and low resistivity required. For all separators, effective resistivity has been found to depend on the free space allowed, the strength of this effect increasing with separator hydrophobicity. Nickel electrodes, plasma-sprayed with nickel/aluminium or nickel/stainless steel powders, gave good electrocatalytic activities with high stability. The second program, development of Electrolyser Inc.'s advanced unipolar electrolysis technology, has benefited from the IEA activity. Performance results obtained with three 100-kA cells of the Generation I design after more than 1000 hr of operation are presented, together with results obtained in the Generation II configuration over a 5000 hr period.