text: This type of battery exhibits a high energy density, high efficiency of charge/discharge (89—92%), long cycle life, and is made from inexpensive, non-toxic materials. However, the operating temperature of 300 to 350 °C and the highly corrosive nature of sodium make it suitable only for large-scale non-mobile applications. A suggested application is grid energy storage in the electric grid. A 6MW-Hr system has been installed at Tsunashima Japan.