NGK's NAS Energy Storage System is a proven large scale
solution to the integration of variable renewable energy
for replacement of fossil generation

Features of NAS


NAS battery makes 24/7 power supply
feasible with solar power 6-10 hours and NAS battery 14-18 hours at 1/3 of rated output.


NAS is the most effective battery to store large amounts of electric energy discharging for 6 hours at rated output.


NAS can be flexibly deployed
where it is needed in less space
than other battery technologies.


NAS is reliable and safe by design and proven operation.


Minimal maintenance and staffing required with our Remote Monitoring System.


Electric energy is stored and delivered within tens of milliseconds of an electronic command.

Structure of NAS Energy Storage System

The Easiest Way to Achieve Multiple Megawatt-Hour Energy Storage System

The NAS battery system is designed to be easily able to expand the capacity as much as needed in one site or several separate sites. The scalability of NAS installation to many 10s or 100s of MW for durations of 6 to 7 hours is at a scale that can defer or eliminate some transmission, distribution and generation investments especially when used in association with variable renewables for a clean solution. (The current largest system at one site is 50MW, 300MWh.) The construction leadtime is significantly shorter than upgrading or building transmission/distribution lines or substations.

A NAS battery system consists of battery enclosures, battery modules and a PCS (AC/DC power conversion system) as the main components. The NGK scope is the battery enclosures and battery modules. NGK works with several PCS manufacturers to complete the battery system.
It is also suitable to install in severe weather conditions, because the battery enclosure and insulated battery modules can resist a wide range of environmental conditions and climate.

New container type unit

The NAS battery system is a “Plug and Play” design built around standard 20 foot ocean freight containers. The containerized design expedites transportation and installation and helps minimize installation costs.

Rated Output 800kW and 4,800kwh
Configuration Four container subunits,series connected.
A subunit includes six NAS modules, each rated at 33kW and 200kWh.
Dimension 6.1W x 5.6D x 5.5H (m)
Weight 86tonnes

Package type unit

The enclosure package and battery modules are installed on site. This design achieves more compact system comparing with containerized design.

Rated Output 1,200kW and 8,640kWh
Configuration 40 NAS modules, each rated at 30kW and 216kWh.
Dimension 10.2W x 4.4D x 4.8H (m)
Weight 132tonnes

Principle of NAS Battery

Battery Cell

NAS battery cell consists of sulfur at positive electrode, sodium at negative electrode as active materials, and Beta alumina ceramic. Beta alumina ceramic is one of NGK's key technologies, which is mounted between sodium and sulfur as electrolyte.
This hermetically sealed battery cell is operated under the condition that the active materials at both electrodes are liquid and its electrolyte is solid.

Operating Principle


If a load is connected to terminals, electric power is discharged through the load. During the discharge, sodium ions converted from sodium in a negative electrode pass through solid electrolyte then reach to sulfur in positive electrode.
The electrons finally flow to outside circuits. The electric power is generated by such current flow.
With the progress of the discharge, sodium polysulfide is formed in positive electrode; on the contrary, sodium in negative electrode will decrease by consumption.


During the charge, the electric power supplied from outside form sodium in negative electrode and sulfur in positive electrode by following the reverse process of the discharge. Because of this, the energy is stored in the battery.

NAS and the NAS logo are trademarks of NGK INSULATORS, LTD., registered in the U.S. and other countries.