R & D on hydrogen storage materials have been carried out since 1974 when so-called “oil crisis” occurred. Recently, after the Japanese government announced “Carbon neural achieving in 2050”, hydrogen energy has attracted much more attention than before. The New Strategic Energy Plan that decided by the cabinet in October 2021 mentions hydrogen is utilized in all the energy sectors. Hydrogen storage materials are applied to large scale hydrogen transport, storage of fluctuated renewable energy in the form of hydrogen, storage of hydrogen nearby building and residential houses and so on. Large scale and long-term national projects for commercialization of large-scale hydrogen transport are starting. However, promotion of fundamental scientific research and basic technology development are also strongly desired.

The hydrogen-based autonomous energy supply system “H2One” that can provide stable electric power using renewable energy has been developed. Since the first unit started into operation in April 2015, several variations of the model were put into operation in total 14 systems so far September 2021. Regarding the concept of H2One, that can supply CO₂-free energy by local production for local consumption, various developments such as large-scale systems in off-grid areas of remote islands, and small-scale models for detached domestic houses are examined on simulation basis. The hydrogen storage technologies for the H2One system are also described.

Shimizu and AIST have jointly developed a hydrogen utilization system that produces hydrogen using surplus electricity from renewable energy, stores it safely in hydrogen storage alloys, and generates heat and power by using fuel cells. The demonstration of the developed system had been carried out by installing the system to a building in the central wholesale market of Koriyama City, for two years. We have evaluated CO² reduction using the system toward the realization of zero energy building. Based on the development results, we have implemented a designed system suitable to the Shimizu’s Hokuriku branch in Kanazawa City, which can store hydrogen of 1,350Nm³ indoors. We are also developing a technology to utilize hydrogen brought in throughout a tentative supply chain. Hydrogen produced at AIST’s renewable energy power plant was compressed and transported to the market to expand the amount of hydrogen used for the realization zero energy building.

Hydrogen storage alloys can store large amounts of hydrogen safely. The rapid spread of renewable energy sources has led to the development of hydrogen energy systems. The tanks using these hydrogen storage alloys have been developed since the 1970s, and are suitable for use in these hydrogen energy systems. In this paper, the status of the development of hydrogen storage alloy tanks and the future prospects are presented by focusing on the projects of their installation in Japan.

This project demonstrates a low-pressure hydrogen-supply chain consisting of hydrogen production using renewable energy generated at a wind power-plant owned by the city of Muroran, hydrogen delivery to a hydrogen utilization facility using hydrogen absorbing alloy tanks (MH tanks), where the low-pressure hydrogen is used.

The hydrogen delivery system with unused heat from a hot bath facility. In addition, a hydrogen utilization facility was also installed at a public facility without heat supply from the facility. We are conducting demonstrations with a focus on future actual operations and disaster countermeasures. Hydrogen is also expected to be used as energy during disasters.

This project demonstrates both hydrogen production using electricity generated from the wind-power plant and the hydrogen delivery system for facilities and buildings in city blocks. (1) Hydrogen is produced by water electrolysis using the power generated at the Shukuzu wind power-plant. (2) Hydrogen is delivered to the hot bath facility, “Yurara” and the public facility, “Kiran” using the on-board MH tanks on trucks, and then (3) transferred to stationary MH tanks located at the buildings. (4) Electric power and hot water generated by hydrogen from the stationary MH tanks using fuel cells at each building are supplied to “Yurara” and “Kiran” (electric power only).

Hydrogen has been enthusiastically researched as a clean energy source that emits no greenhouse gases. Therefore, there are requirements for safe methods to manufacture, store, and transport hydrogen. Conventionally, hydrogen storage materials are metal hydrides and metal amides that react violently with moisture, and their usage environments are limited by the extreme conditions required for hydrogen gas generation. Metal-organic frameworks (PCP/MOFs) are porous coordination materials that are composed of organic ligands and metal ions. Because of their ability to efficiently adsorb small molecules, PCP/MOFs have potential applications in e.g., gas adsorption, catalysis, as well as energy storage and conversion. Functionalization and modification of the organic ligands to construct new MOFs are fascinating and significant areas in crystal engineering owing to the potential applications of the resulting materials. We describe the synthesis and gas-adsorption properties of novel MOFs using the functionalized organic ligands.

Ammonia (NH₃) is recognized as an attractive hydrogen (H₂) and energy carriers because it has a high gravimetric H₂ density of 17.8 wt% and highest volumetric H₂ density of 10.7kgH₂/100L. The gravimetric H₂ density is third largest after NH₃BH₃ and LiBH₄. The volumetric hydrogen density is 1.5-1.7 times of liquid hydrogen, and it is easily liquefied under about 1 MPa at room temperature. NFPA flammability of NH₃ is low because of the high flash point. NH₃ and liquid H₂ have a same high NFPA health hazard of 3. Proton-based solid acids such as zirconium phosphate for the vapor concentration (vapor pressure) and the nitrogen concentration in water lowering will be used to reduce the negative effects on the environment. Green ammonia will be synthesized using renewable energy (renewable electricity), water, air and Haber–Bosch process. Ammonia for fuel has advantages as an energy carrier for electric power plants, industrial furnaces, bunker fuel, solid oxide fuel cell (SOFC) and a hydrogen carrier for mobilities.