Fuels – Hydrogen – Hydrogen Production | Electrolysis

Water electrolysis is an electrochemical process in which electricity is used to split water into two gases, hydrogen and oxygen. Three main technologies can be distinguished according to the electrolyte used in the electrolysis cell: alkaline electrolysis with a liquid electrolyte; polymer electrolyte membrane (PEM) electrolysis with an acidic ionomer; and high-temperature (HT) steam electrolysis with a solid oxide as the electrolyte. This article provides an overview of the technical implementation of these three technologies. Given that alkaline water electrolysis is well established as an industrial technology for decades, this article focuses on PEM electrolysis and discusses the latest developments. Some results of a unitized regenerative fuel cell based on PEM technology are also given. Finally, a short overview of the process of HT steam electrolysis is presented.