Abstract: NGK has developed a sodium sulfur battery (NAS® battery) for load leveling applications, allowing the grid to deal with increasing peak. The recent growth in environmentally friendly renewable energies causes network instability. A secondary battery based energy storage system is seen as one of the strongest solutions to stabilize the network while improving the efficiency and usability of these renewable energy technologies. The NAS battery features long duration discharge, compactness, and a long lifespan of 15 years. The capacity for long duration discharge is one of the most notable features of this technology, a feature which becomes more important as renewable energy generation increases. In this paper, recent design of the NAS® battery system is detailed, and a few applications are described.

Key words: sodium sulfur battery, energy storage