System and methods for supplying electric power to a power grid are disclosed. The system includes a power generation source, a charging station for charging a zinc-based energy storage device from the power generation source, and a transport module for transporting the zinc-based energy storage device. The system also includes an input station for supplying power to the power grid from the zinc-based energy storage device, and a controller for selectively discharging the zinc-based energy storage device to the power grid based on the initiation signal.