Continued from Honda Uses 100MWh NAS Battery for Grid Stabilization (1)
Incorporates gas engines and VOC generator for optimum control
The center incorporates a cogeneration system using gas engines and a volatile organic compound (VOC) generator, in addition to solar power generation systems and NAS batteries.
It took about 10 years for the company to thoroughly understand the issues on actual use of NAS batteries on site, which even manufacturers do not notice, according to the company (Fig. 5).
When the NAS batteries are fully discharged during peak power consumption hours in summer, the output has to be limited for several hours immediately after discharge because of the batteries heating. The center has been searching for a solution regarding what should be done to optimize the use of the batteries in collaboration with other power sources at the center while considering the risk of excessive demand.
Because NAS batteries are operated at a high temperature of 300°C, consideration should be given to the loss due to electric heaters. In terms of the environmental value, the loss is the factor that increases the power cost and carbon dioxide (CO2).
In consideration of this factor, the company expects that the NAS batteries can be used for absorption and leveling of excess power as measures against output control such as the one implemented in the Kyushu region, in combination with solar power generation systems.
Maintenance of the NAS battery system includes inspection of inverters and cleaning of filters. Maintenance is performed in the seasons when the demand for power is low because the operation needs to be stopped in the meantime. The batteries are divided into three blocks with 4MW of output each, and operation of the blocks is stopped one by one for precise inspection, etc. The NAS battery system is operated under a 15-year lease contract.