As the power generated by renewable energy systems tends to vary according to the weather conditions and the installation sites of such systems tend to be unevenly distributed, power-to-gas (P2G), a system in which surplus electric power is converted into hydrogen gas through water electrolysis to serve as a gaseous energy carrier for the storage and transport of energy, has been attracting attention in recent years. Polymer electrolyte membrane (PEM) water electrolysis systems are capable of rapidly responding to the output power fluctuations of renewable energy systems. However, a disadvantage of these systems is that they require large amounts of costly precious-metal catalysts in order to achieve high efficiency and long-term durability.
To reduce the amount of precious-metal catalysts required, the Toshiba Group has developed the following two technologies: a proprietary nanostructure control technology using a sputtering method, and a hydrogen leakage suppression technology for membrane electrode assemblies (MEAs). From the results of experiments on a PEM water electrolysis system using these technologies, we have confirmed that it achieves a 90% reduction in required precious-metal catalysts compared with conventional systems while maintaining efficiency and durability. We have also succeeded in increasing the size of the MEA by suppressing the formation of wrinkles in the electrolyte membranes, making it possible to manufacture large-scale PEM water electrolysis systems.