Development of long cycle life valve-regulated lead-acid battery for large-scale battery energy storage system to utilize renewable energy

The electric power generation system using the renewable energy has the essential problem of the output fluctuation. With expanding deployment of renewable energy, it is necessary to smooth the fluctuation of both long and short term frequency. One of the solutions to solve this problem is combining the renewable energy and the storage batteries. It is important to install the large storage system with low cost, long life, and safety. The batteries with large capacity, and high input and output power properties are required. We developed long life VRLA batteries for the load leveling by utilizing nighttime energy storage, LL type VRLA batteries. Then, LL-W type VRLA battery with life expectancy of 17 years for the smoothing the output fluctuation have been developed. These batteries have been applied to control the power fluctuation absorption of the power grid. Furthermore, the VRLA battery which improved input and output power properties, the LL-WS type, was developed.