NAS Battries

About NAS Batteries

Operation principle

During discharge

  • Molten sodium donates electrons to the external circuit at the anode
  • The resulting ions Na+ migrate to the cathode through the beta-alumina solid electrolyte that separates the two liquid electrodes and that acts as a superionic conductors
  • The volume of liquid at the anode therefore decreases
  • Arriving at the cathode, Na+ ions combines with molten sulfur which reacts with the electrons coming from the external circuit, forming sodium polysulfide Na2Sx
  • The volume of liquid at the cathode therefore increases

2 Na + x S → Na2Sx with 3.3 ≤ x ≤ 5

During charge

  • The reverse process takes place

Battery Cell

Voltage 2V
Energy density 367 Wh/l
222 Wh/kg
Power density 36 W/kg
C-rate 1 / 6 = 0.17
Optimal temperature range 300 - 340°C
Maximal temperature range 290 - 360°C
Life time 4500 cycles
15 years

Features of NAS Batteries

NGK's NAS batteries are large-capacity batteries with many power grid applications.
Superior function and performance possible only from decades of research, design, testing, demonstration, advanced manufacturing and over 15 years of proven commercial operation.

Long Duration NAS batteries are the most effective way to store large amounts of electrical energy discharging for six hours at rated output.
24/7 Power Supply NAS batteries make 24/7 power supply feasible with solar power for 6-10 hours and a NAS battery for 14-18 hours at one-third of the rated output.
Fast Response When used with a fastPower Conversion System(PCS), NAS systems can respond to grid commands to store or deliver electrical energy in tens of milliseconds.
Compact NAS batteries can be flexibly deployed in smaller spaces than other battery technologies.
High Reliability With decades of experience, NAS batteries have field-proven reliability exceeding 99%.
Safety The safety of NAS batteries has been proven in testing by NGK and third-party authorities and from extensive field experience.
Developed for Grids Development of NAS technology by NGK started in 1984 to provide a more flexible energy storage alternative than pumped energy storage, for the world's largest utility, TEPCO. The first NAS battery system deployment was in 1995.
System Expansion NAS battery systems can be cascaded to any needed size (to 100s of MW or more).
Minimal Maintenance Preventative maintenance is minimal and can be scheduled to avoid peak seasons. Maintenance can be done on partical systems while the rest of the system continues operation.
Wide Ambient Operating Range Climates for NAS projects range from the cold of Canadian winters to the heat of Abu Dhabi.
Long Lifetime NAS batteries are rated at 4,500 full cycle discharges, or a 15-year calendar life, whichever occurs first. This lifetime is field-proven.
Plug & Play Containerized NAS batteries, in which NAS battery modules are pre-installed, drastically reduce installation periods.

Major Advantages of NAS over other battery technologies

Long duration

NAS battery is a large-capacity, long-duration storage battery suitable for daily load leveling and time shifting of wind and solar generation.

Long life expectancy

NAS battery has a calendar life of 15 years and a full charge/discharge durability of 4500 cycles.Since the active materials of the NAS battery are in molten states, there are no transition between solid and liquid due to charge and discharge, and there is no side reaction, so long life can be expected.

Tolerance for cold and high temperature environment

NAS battery, which operates at 300-340 degree C. in a thermal enclosure, satisfies optimal operating conditions without air conditioning in cold and hot areas.

Customer's Voice

By courtesy of BC Hydro, their video and article shown left and below introduce how NAS has contributed to BC Hydro's innovative energy storage project in British Columbia, Canada.

About BC Hydro's Field Battery Energy Storage Project:

Watch the project video

Read the detailed article

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

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