Conceivable Applications

Sodium sulfur (NAS^®) batteries produced by NGK 
Insulators Ltd. (NGK)  are presently the only
commercially mature, large-scale energy storage technology that can be installed anywhere.
The active materials in NAS batteries are sulfur at the positive electrode and sodium at the negative electrode, and the electrolyte is a sodium ion conductive ceramic composed of beta-alumina. NAS battery systems boast an array of advanced features, such as large capacity, high energy density, long life, and compactness.

NGK markets NAS batteries for use in grid storage (especially for use in conjunction with intermittent renewable energy sources such as wind and solar). The battery systems have applications in peak shaving, load leveling, and emissions reductions. They can be used as emergency power supplies, or they can provide power for ancillary services, grid frequency controls, and reactive power compensation. They can also serve as the central components
of a smart grid.

Competitive Advantage

Large Capacity
NAS battery has more than 6 hours of capacity. A single battery system can be used for long energy shifting, peak shaving, grid frequency control, emergency power supply, and multiple other applications.

Compactness
The 200-kW/1200-kWh battery is available in a 20-ft ISO shipping container.

Plug & Play solutions 
Users can noticeably save transportation and construction costs with fully containerized battery units.

Long Life and Durability
Less capacity deterioration with no need for battery replacement until the end of life (4,500 full cycles or 15 years). NAS batteries work in a wide range of ambient temperatures (－20 ~+45C°) *¹.
*1: The acceptable ambient temperatures can be increased to -45 ~ +55 C°by specific design modification upon customer request.

Many Years of Field Service
NGK’s NAS battery has been commercialized since 2002, and the total global installation figure is approx. 530 MW/3700 MWh.

Easy Operation and Maintenance
There is no self-discharge, and uniform charge is not required.
Preventive maintenance is minimal since only consumable parts should be periodically replaced. Furthermore, maintenance can be scheduled to avoid peak operational seasons.

High Safety and Reliability
The safety of NGK’s NAS battery cell is proven through its having earned the UL label in The US. The NAS Battery system also has the CE label in the E.U.

No concerns regarding raw material depletion
Sodium and sulfur (the major raw materials for NGK’s NAS battery) exist naturally in the world, so there are no concerns of raw material depletion.

Performance

A summary of the NAS battery features are listed below;
・Large capacity: rated power x 6 hours
・High energy density: 1.4 kWh/m³, 57.1 Wh/kg as a 20ft Container
[As a reference for footprint, 47 m² /MWh-ac including BoP (as a recent actual result at Buzen, Kyushu, Japan)]
・Fast response: within one (1) millisecond (full power charge to full power discharge, full power discharge to full power charge)
・Long life: 15 years or 4,500 full discharge (100% Depth of Discharge) cycles
・No self-discharge; No need for uniform charge
・Applicable to a wide range of ambient temperatures (－20 ~+45C°)*¹
*1: The acceptable ambient temperatures can be increased to
-45 ~ +55 C°by specific design modification upon customer request.

 

Technical maturity

The current total worldwide installed capacity (including under construction) of NGK’s NAS battery systems is approx. 525 MW (3,560MWh), as of March 2018. (The following table shows the breakdown by region.)
                                                                      

	Output	Energy
Japan	360 MW	2510 MWh
Europe	37 MW	260 MWh
North America	20 MW	140 MWh
UAE(*)	108 MW	650 MWh

                                                  (*)Including sites under construction.

Conceivable risk

Appropriate maintenance work should be executed in accordance with NGK’s maintenance procedure. In
case users do not properly handle the maintenance work, they could fail to realize the product’s expected performance.

Information on patent related to this technology

Five representative patents:
(JP) P4750549
(JP) P4574196
(JP) P4289948
(JP) P4076331
(JP) P3329700

*Total active patents: 149 (as of March 2018)

Name	NGK INSULATORS, LTD.
Address	2-56 Suda-cho, Mizuho, Nagoya 467-8530, Japan
Capital	JPY 69.8 billion (as of March, 2017)
Contact person	Mr. Kodai Okano Phone: +81-52-872-7515 Fax : +81-52-872-7530 E-mail: okano-k@ngk.co.jp URL for inquiry: https://www.ngk.co.jp/nas/
Number of employees	Consolidated Full-time: 17,517 (As of March 31, 2017) Contract & Temporary: 3,451 (Avg. in FY2016)
Date of company foundation	May 5, 1919
The type of business	Manufacture and sale of electric power related equipment including insulators, and of ceramic catalyst carrier for exhaust gas purification, and of industrial products, and of beryllium copper products

 

International operation

Number of employees for international operation		Consolidated: 13,658                   (as of March 15, 2018)
Overseas        offices	City, Country	Name of Company (if applicable)
	Salford, England	NGK BERYLCO U.K. LTD.
	Baudour, Belgium	NGK CERAMICS EUROPE S.A.
	Taunus, Germany	NGK EUROPE GmbH
		NGK DEUTSCHE BERYLCO GmbH
	Gliwice, Poland	NGK CERAMICS POLSKA SP. Z O.O.
	Couëron, France	NGK BERYLCO FRANCE.
	CapeTown, South Africa	NGK CERAMICS SOUTH AFRICA(PTY)LTD.
	Hebei, China	NGK INSULATORS TANGSHAN CO., LTD.
	Shanghai ,China	NGK INSULATORS (CHINA) INVESTMENT CO., LTD.
	Jiangsu, China	NGK TECHNOCERA SUZHOU CO., LTD.
	Seoul, Korea	NGK AUTOMOTIVE CERAMICS KOREA CO., LTD.
	Haryana, India	NGK TECHNOLOGIES INDIA PVT. LTD.
	Bekasi, Indonesia	P.T. NGK CERAMICS INDONESIA
	Saraburi, Thailand	SIAM NGK TECHNOCERA CO., LTD.
	Victoria, Australia	NGK STANGER PTY. LTD.
	Baltimore, MD, U.S.A.	NGK-LOCKE INC.
	Virginia Beach, VA, U.S.A.	NGK-LOCKE POLYMER INSULATORS, INC.
	Mooresville, NC, U.S.A.	NGK CERAMICS USA, INC.
	Novi, MI, U.S.A.	NGK AUTOMOTIVE CERAMICS USA, INC.
	Fremont, CA, U.S.A.	FM INDUSTRIES, INC.
	Santa Clara, CA, U.S.A.	NGK ELECTRONICS USA, INC.
	South Sweetwater, TN, U.S.A.	NGK METALS CORPORATION
	Ontario, Canada	NGK INSULATORS OF CANADA, LTD.
	Nuevo León C.P., México	NGK CERAMICS MEXICO, S. de R. L. de C. V.

 

Modality of business transaction

Partnership
NGK would like to export the product and entrust the maintenance work to the local partner after completion of NGK’s maintenance training to the local partner. 

Export of product
NGK would like to directly export our products from Japan at the beginning stage. However deployment of local sales representative can also be considered depending on market demand.

Schematic  illustration of the technology

Figure 1: Principles of Sodium Sulfur Batteries

NAS batteries consist of a beta-alumina solid electrolyte, sodium as the negative electrode, and sulfur as the positive electrode. Figure 1 shows the discharge and charge reactions for the NAS battery. During discharge, sodium ions move from the negative electrode to the positive electrode through the beta-alumina, creating sodium polysulfide. When charging, the sodium ions return to the negative electrode. The internal temperature of the battery module is kept at around 300 °C by the electric heaters equipped in the thermal insulated enclosure, to maintain all active materials in a liquid state.

Figure 2: Structure of Containerized NAS Battery Systems

The battery cell is cylindrical in shape and consists of sodium at the center and sulfur at the outside. A module contains many cells within a vacuum insulated thermal enclosure in which the temperature is properly controlled. The outer double-layer vacuum insulation minimizes heating power, dramatically improving system efficiency. A 200-kW (1,200-kWh) Containerized Battery consists of six (6) integrated battery modules and controllers in a 20-foot shipping container. This standard 20-foot ISO container can be transported by sea, vehicle, or train. The 200-kW container can be connected in series with up to four (4) containers to compose up to an 800-kW subsystem. Figure 2 shows the structure of this containerized NAS battery system.

For further information, a product outline, brochures, movies, specs, and case studies, visit the following URL:
https://www.ngk.co.jp/nas/