H2 generation from alkaline electrolyzer

Water electrolysis is a promising approach to hydrogen production from renewable energy sources. Even though it is not necessarily environmentally friendly and a large number of possible feedstocks for hydrogen production include fossil resources such as coal, natural gas, and mineral oil, but also biomass, water, and components such as ethanol, methane, or ammonia can be used for hydrogen production. Also, a large variety of different energy sources can be used for hydrogen production. The combination of hydrogen production with renewable energy systems, such as photovoltaics, hydropower, or wind energy is very suitable though. Many innovative processes have been subject to intense research and some have already reached high efficiencies. Alkaline water electrolyzers with anion-conducting membranes hold many advantages in comparison to other systems. As cheaper, non-noble metals are stable in alkaline media, the relatively low cost of the electrode materials is one of the main advantages of alkaline systems over electrolyzers using proton-conducting electrolytes. Therefore, the main part of published literature on alkaline electrolysis describes electrodes based on low cost materials such as nickel for both anode and cathode. Yet still alkaline water electrolyzers have to compete against other forms of hydrogen production, such as steam reforming of natural gas. Even though many studies expect water electrolysis to become economically viable on a long-term basis, conventional hydrogen production is still hard to under-price. (C) 2014 John Wiley & Sons, Ltd.