Power-to-hydrogen systems

Power-to-hydrogen (P2H), or the production of hydrogen from electricity based on water electrolysis, is a key element of future energy systems that is compatible with the flexible exploitation of massive, nondispatchable renewable power generation, like wind and solar photovoltaic. This chapter firstly describes the fundamentals and operating principles of hydrogen generation through electrolysis, with a review of the main electrolyzer types (using alkaline, polymeric-membrane, or solid-oxide electrolytes) and their performance, also briefly addressing the main options for subsequent hydrogen storage. Then, the coupling of P2H with renewable energy is discussed, presenting two case studies referring to the use of solar photovoltaic or wind power electricity, where hydrogen is either exported to consumers or injected into the natural gas grid. Finally, the general sector coupling potential of the P2H technology in the energy system is presented.