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Electric power generation systems using renewable energy sources have an advantage of no greenhouse effect gas emission. Using these systems, we have the essential problem of the fluctuation of electric power output, however. In order to solve this problem, one of the solutions is the combination of the renewable energy system with the battery energy storage system. The VRLA batteries manufactured by Shin-Kobe have been used in order to smooth the fluctuations of the wind power generation. On the basis of these findings, Shin-Kobe has newly developed a VRLA battery, the so-called LL-W type, expected more than 17 year life for the use in the system of wind power generation. Before this LL-W type VRLA battery, Shin-Kobe has already applied VRLA batteries as a LL type to the wind power generation system. On the basis ofteardown analyses of the LL type batteries, 7 year life of these batteries has been already proved, as of this time, and the LL type batteries have been still working in the system. The main failure mode of the batteries has been estimated as the corrosion of positive grids. In this practical system of the power generation, on the basis ofteardown analyses, the life of the LL type battery was evaluated to be 9 years, although the life of the newly developed LL-W type VRLA battery has been expected to be more than 17 years.

Fe-Co alloys are promising materials for high power density motors, since they have higher Bs than Fe-Si steels which are most commonly used as the motor cores. It is known, however, that the Fe-Co alloys generally have poor workability due to an existence of the brittle phase, ordered B2. In this study, effects of Co content and Si/Al addition with the Fe-Co alloys on the workability and magnetic properties were investigated. The neutron diffraction measurements of the Fe-Co alloys with different Co contents of 5, 18, 27, and 49 mass% were first conducted to know the existence of the ordered B2 phase. The result showed that the B2 phase was observed in the Fe-Co alloys with Co contents of 27 and 49 mass%, while the alloys with 5 and 18 mass% did not contain it, which suggests the latter two alloys have the better workability. Then, we checked the effect of Si/Al addition on the magnetic properties of the 82Fe-18Co alloy, and found that the co-addition of Si/Al reduce the coercivity, Hc to about 60 A/m and iron loss to less than 170 W/kg while maintaining a high B value at 30 000 A/m above 2.2 T.

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