Abstract
This paper describes functional use of water electrolysis in the future energy system using hydrogen as energy carrier. It mentions that the conversion efficiency from electricity to hydrogen in PEWE (Polymer Electrolyte Water Electrolysis) may become close to 100% in near future, and may even exceed 100% when external heat will be given to the electrolyzer, though a technical breakthrough in R&D of anodic electrocatalyst is required for. The role of water electrolysis among many hydrogen production technologies from fossil fuel and renewable energy is characterized for providing efficient energy conversion means from electricity to hydrogen. Efficient water electrolysis could be applied to the following energy systems : A) power load levering in nuclear power plants through producing hydrogen, B) refueling stations for fuel cell vehicles, C) leveling or storage of intermittent renewable energy (PV and wind). In addition, efficient reversible electrolyzer (unitized regenerative fuel cell) could be applied to system with power load levering function to supply electricity, heat and hydrogen gas to urban building facilities.
