Recently electric vehicles and stationary fuel cells for domestic use, i.e., Enefarms have been commercialized and much concern has been focused on hydrogen supply, especially by electrolysis of water. General aspect of electrolysis of water has been given and discussed. Among the present energy resources, the best and the easy way of hydrogen production is to use fossil fuel. However the strict limit of CO2 emission, electric energy should be supplied by the recycling natural energy sources. Wind and solar energy are mild and suitable for energy supply without emission of hazard materials. However, the energy supply is quite changeable, therefore the electrolyser should be durable for heavy duty.
The method of hydrogen production including traditional electrolysis of water and the alternative electrolysis for hydrogen production have been shown and discussed.
In hydrogen energy system, the high efficiency of energy conversion is required for hydrogen production and hydrogen use. Water electrolysis and fuel cells are key technologies to convert electricity and chemical energy conversion is required for hydrogen production and hydrogen use. Water electrolysis and fuel cells are key technologies to convert electricity and chemical energy reversibly. The major source of the efficiency loss is not hydrogen electrode reactions but oxygen electrode reactions. In recent years, high-level not hydrogen electrode reactions but oxygen electrode reactions. In recent years, high-level theoretical tools and computational researches have led to significant progress in the atomic-level understanding of the oxygen electrode reactions and factors which affect the catalytic activities. In this review, we summarize previous and the most recent theoretical predictions and experimental results in the field of oxide-based electrocatalysts for the oxygen electrode reactions.
Advanced alkaline water electrolysis system has been developed, which is based on our world top-level brine electrolysis technologies. Using the system, low-cost green hydrogen can be made at high efficiency from renewable energy such as wind power and photovoltaic power. In this system, hydrogen can be produced at about 82% energy conversion efficiency (HHV) by applying a current density of 0.6A/cm2 and at 90% HHV by applying a current density of 0.2A/cm2. Compared to conventional ones, it is possible to produce three times amount of hydrogen at the same 82% HHV on the same area of the electrode. The performance and durability of the system with fluctuating power are evaluating. The system can rapidly respond to precipitous change of electricity. A system equipped with the commercial size electrode (about 3m2) started demonstrating in 2015 in Yokohama-city.
By expansion of the introduction of the renewable energy utilization, the storage of surplus electric power and the absorption of the fluctuation are necessary. “Power To Gas” using the electrolysis can be one of the solution to those problems, and hydrogen is a candidate medium for the energy storage. The High temperature steam electrolysis with solid oxide electrolysis cell (SOEC) is prospective for higher efficiency than conventional low temperature electrolysis methods. Toshiba is developing hydrogen production system using SOEC and electrical power storage system with SOEC/SOFC. The electrolysis properties have been evaluated with cell and stacks. A part of this study is carried out in a project commissioned by METI and NEDO.
Honda has been conducting research and development on the comprehensive technology related to hydrogen, not only fuel cell vehicles but also hydrogen generation and hydrogen application. In the hydrogen generation area, Honda has developed Smart Hydrogen Station (SHS) using Honda’s unique high differential pressure water electrolysis technology. This technology can achieve small and effective hydrogen generation using renewable energy. SHS was installed in the Saitama prefectural office in 2012 as a verification project under the consignment of Ministry of the Environment. In the process of obtaining official authorization and installing of SHS in Saitama, several problems related to legal and safety issues came up. Honda has solved these problems. The experimental project successfully finished in July 2015. Next generation SHS embodies all devices including high differential pressure water electrolysis stack, storage tanks and a dispenser in one unit that makes it easy to install in variable location at reasonable cost.
The World Energy NETwork (WE- NET) project was an outstanding national project which was highly evaluated globally. Talented and creative experts gathered from industry, government and academia with the aim of establishing a world energy network using hydrogen. During 2001-2002 I participated in division tasks 4, 10 and 12 of the project. Based on my real experiences, I would explain about the activities of the organization, management as well as research and development.