Items related to hydrogen from renewable energy in Japan’s five energy-related strategies and global warming countermeasures plan are described. Japan’s energy strategy is made with the aim of ensuring safety, stable supply of energy, improvement of economic efficiency, and adaptation to the environment. The contents are composed of scenarios to realize a trend of technological development to realize a hydrogen society and realization of a low carbon society. In promoting the plan, the region that produces renewable energy is required to develop economically. In order to realize them, it is necessary to develop not only hydrogen but also production technology of chemical substances from renewable energy as well as by-product oxygen considering the characteristics of the region.
Power to Gas has a number of technology options. In terms of produced gas, not only hydrogen produced directly from renewable energy but also carbon neutral methane and fuels synthesized from hydrogen and carbon dioxide captured from concentrated emission resources can be candidate. Power to Gas also provides a variety of applications, ranging from ramping capability and long term energy storage in accordance with large scale variable renewable energy grid connection to supplier of decarbonized gas to the other sector than the power grid. It is required in Japan aiming establishing hydrogen economy that the objective of deployment of Power to Gas should be clearly identified from long term perspective, either regarding Power to Gas as a passive option for the grid stability or as active measure for decarbonization of the whole energy system including power sector, gas network and transport sector through sector coupling.
Fukushima Renewable Energy Institute, AIST (FREA) was established in Koriyama city of Fukushima in April 2014. FREA aims are to be a global innovation hub concerning renewables, through creative “Fukushima” technologies. Renewable energies are valuable domestic energy resources for Japan and essential for the prevention of global warming as well as for sustainable development. There are high expectations for mass deployment of renewable energy, but its wide use raises various issues that must be solved, including output fluctuation, high cost and regional variability. FREA has been developing technologies for storing and utilizing a large amount of renewable energy that will help solve several energy issues facing Japan. We have been developing technologies for converting renewable electricity into hydrogen or hydrogen energy carriers (methylcyclohexane (MCH), ammonia, liquid hydrogen (LH2), etc.), which is utilized by generating electricity, heat, and hydrogen. These technologies are useful for stabilizing the power grid even when massive amounts of renewable energy are introduced in the future. The result will be the efficient use of a much greater amount of renewable energy regardless of the location and season.
In this report, the results of R&D for the hydrogen systems in FREA are introduced.
Hydrogen production from water by using photocatalysts and/or photoelectrodes under solar irradiation has attracted much attention as a method of clean hydrogen production. In this articles, recent developments of water splitting systems under visible light irradiation are reviewed mainly focusing on photocatalyst materials. In addition, photocatalytic water splitting reactors for large scale application are described.
Hydrogen production from biomass was overviewed, and its present situation is explained. There are 4 technologies that can be used for biohydrogen production: high-temperature gasification, supercritical water gasification, methane fermentation, and hydrogen fermentation. Steam reforming and carbon dioxide separation is needed afterward. Due to the lack of utilization and high cost, biohydrogen has not been widely utilized. To introduce biohydrogen, characteristics of biohydrogen should be considered, and strategic approach is wanted.
Honda has developed a package type Smart Hydrogen Station (SHS) using a unique high pressure water electrolysis technology. This system contains major components in a 10ft. size enclosure in order to save its footprint and install easily. The performance of SHS was improved by reducing excess water by optimizing purity level of deionized water. Durability of the system was also improved by changing the method of high pressure water draining. The area where SHS can install was expanded to semi-cold area by equipped a heater for ventilation and hot tube for water circulation. SHS has been installed at 17 locations in Japan and refueling regional FCVs. Also, experimental 70MPa SHS was installed in Tokyo as a Ministry of Environment subsidized project. This project aimed to validate reducing CO2 by generating hydrogen from electricity generated by renewable energy.