Water Electrolysis with Solar Electricity
The chemical and basic thermodynamic aspects of water electrolysis are presented, focusing on maximizing the efficiency of hydrogen production. Current and emerging electrolytic technologies, with their advantages and limitations, are discussed. Photovoltaic (PV)-assisted water electrolysis is then presented with reference to real applications of the technology, made using direct coupling of the electrolyser to the PV array or mediated by a maximum power point tracker. The economics of water electrolysis do not depend on the cost of solar electricity only, but also on the overall efficiency of the process, including compression and storage of the hydrogen gas obtained. The way to reduce the cost of electrolytic hydrogen, therefore, involves crucial advances in lowering the cost and enhancing the efficiency of both current electrolysers and hydrogen compressors. A number of emerging electrocatalytic (and compression) technologies are therefore reviewed, showing the scope and potential impact of contemporary global research and development efforts in this area. The large applicative potential of this flexible technology, which enables truly distributed energy generation, is critically discussed.