Batteries for Large-Scale Stationary Electrical by Daniel H. Doughty, Paul C. Butler, Abbas A. Akhil, Nancy H. Clark, and John D. Boyes

arge-scale stationary battery There are many examples of large- modes of traditional lead-acid batteries.5 energy storage has been under scale battery systems in the field. Table In these applications, we would like to Ldevelopment for several decades I provides a short list of examples of have relatively deep discharges with with the successful use of pumped installed large battery systems. good cycle life. Recent studies at Sandia hydroelectric storage as a model. Secondary batteries, such as lead- have shown that new carbon-enhanced Several large battery demonstration acid, nickel-cadmium, and lithium- negative in valve-regulated projects have been built and tested batteries can be deployed for energy lead-acid (VRLA) batteries have under a variety of electric utility grid storage, but require some re-engineering improved cycle life up to a factor of 10 applications. In addition, renewable for grid applications. Two novel classes at significant rates (up to 4C).6 energy sources such as wind and of battery systems that are relevant to Lithium-ion batteries, which have photovoltaics may require energy storage new installations of large energy storage achieved significant penetration into systems. While these applications are systems are sodium/sulfur (Na/S) and the portable/consumer electronics new and expanding, the shift toward flowing batteries. Each of markets and are making the transition an expanded role for battery energy these batteries is briefly described below, into hybrid and electric vehicle storage in the de-regulated electricity and information related to large battery applications, have opportunities in grid market became evident by the late applications is highlighted. storage as well. If the industry’s growth 1980s and early 1990s. Studies by in the vehicles and consumer electronics Sandia National Laboratories identified Secondary Batteries markets can yield improvements and opportunities for battery energy storage manufacturing economies of scale, in the generation as well as on the Grid stabilization, or grid support, they will likely find their way into grid transmission and distribution segments storage applications too. Developers 1,2 energy storage systems currently of the electric grid. Reports from consist of large installations of lead-acid are seeking to lower maintenance and these studies describe battery storage batteries as the standard technology. operating costs, deliver high efficiency, application requirements and provide The primary function of grid support and ensure that large banks of batteries a preliminary estimate of potential is to provide “spinning reserve” in the can be controlled. As an example, in costs and benefits of these applications event of power plant or transmission November 2009, AES Energy Storage for the U.S. electric grid. Applications line equipment failure, that is, excess and A123 Systems announced the fall into two broad categories: energy capacity to provide power as other power commercial operation of a 12 MW applications and power applications. plants are brought online. These systems frequency regulation and spinning Energy applications involve storage can take energy from the grid when reserve project at a substation in the system discharge over periods of either the frequency or voltage is too Atacama Desert, Chile. Continued cost hours (typically one discharge cycle high and return that energy to the grid reduction, lifetime and state-of-charge per day) with correspondingly long when the frequency or voltage begins improvements, will be critical for this charging periods. Power applications to sag. The current implementation can battery chemistry to expand into these involve comparatively short periods of provide a few minutes of energy, but grid applications. discharge (seconds to minutes), short overall grid management, including recharging periods, and often require shifting peak loads, and supporting Sodium-Beta High many cycles per day. renewables, will require longer Temperature Batteries Detailed performance criteria for durations of storage and therefore re- applications such as peak shaving and engineering of conventional storage Rechargeable high-temperature battery load leveling (energy applications) systems to handle greater energy/power as well as frequency and voltage technologies that utilize metallic sodium ratios. Some improvements can be made offer attractive solutions for many large- regulation, power quality, renewable by re-engineering of existing secondary generation smoothing and ramp scale, electric utility energy storage battery technologies; longer discharge applications. Candidate uses include rate control (power applications) are durations will generally require new 2 load-leveling, power quality and peak described elsewhere. Generally, the chemistries and system designs. most important requirements have shaving, as well as renewable energy The lead-acid battery chemistry can management and integration. A number been the need for low cost, flexible be modified for grid storage applications designs, proven battery technologies, of sodium-based battery options have beyond stabilization applications by been proposed over the years, but the and reliable performance. modification of the structures. While many battery technologies variants that have been developed Lead-carbon electrodes are designed the furthest are referred to as sodium- have been proposed and developed for to combine high of a electrical energy storage applications, beta batteries. This designation is used well-designed battery with the high because of two common and important only a handful have actually been used specific power obtained via charging in fielded systems. Technologies that features: liquid sodium is the active and discharging of the electrochemical material in the negative electrode, and are used in fielded systems include lead- double-layer. Lead-carbon electrode acid, nickel/cadmium, sodium/sulfur, the beta-alumina ceramic separator research has been focused on the functions as the electrolyte. Sodium/ and - flow batteries. extension of cycle life durability and Cost effective energy storage systems sulfur technology was introduced in specific power. Carbon is added to the 7 3 the mid-1970s. The advancement of have been identified for utility, end- negative electrodes; while the carbon user, and renewable applications. Other this technology has been pursued in a does not change the nature of the variety of designs since that time. battery technologies, such as the many charge-transfer reactions, it increases lithium-ion batteries, are less mature A sodium-sulfur (Na/S) battery specific power and reduces the incidence is a type of molten metal battery and not yet well-developed for these of sulfation during charging cycles, 4 constructed from sodium (Na) and applications. which is one of the principal failure

The Electrochemical Society Interface • Fall 2010 49 Doughty, et. al. primary disadvantage is the requirement to sodium/sulfur cells. However, (continued from previous page) for thermal management, which is sodium/metal chloride cells include a necessary to maintain the ceramic secondary electrolyte of molten sodium sulfur (S). This type of battery has a separator and cell seal integrity. tetrachloroaluminate (NaAlCl4) in high energy density, high efficiency of In the mid-1980s, the development the positive electrode section, and an charge/discharge (89-92%), long cycle of the sodium/metal-chloride system insoluble transition metal chloride (FeCl2 9 life, and is fabricated from inexpensive was launched. This technology offered or NiCl2) or a mix of such chlorides, as materials.8 However, because of the potentially easier solutions to some of the positive electrode. The advantages operating temperatures of 300°C to the development issues that sodium/ are that the cells have a higher voltage, 350°C and the highly corrosive nature sulfur was experiencing at the time. wider operating temperature range, are of the sodium polysulfide discharge Sodium/metal chloride cells, referred to less corrosive and have safer reaction products, such cells are primarily as ZEBRA cells (ZEolite Battery Research products. suitable for large-scale, non-mobile Africa), also operate at relatively high From the time of their inventions applications such as . temperatures, use a negative electrode through the mid-1990s, these two Sodium β’’-Alumina (beta double-prime composed of liquid sodium, and use technologies were among the leading alumina) is a fast ion conductor material a ceramic electrolyte to separate this candidates believed to be capable and is used as a separator in several types electrode from the positive electrode. of satisfying the needs of a number of molten salt electrochemical cells. The In these respects, they are similar of emerging battery energy-storage

Table I. Examples of installed large scale battery energy storage systems. Name Application Operational Power Energy Battery Type Cell Size & Battery Dates Configuration Manufacturer Crescent Electric Membership Peak Shaving 1987-May, 2002 500 kW 500 kWh Lead-acid, flooded 2,080 Ah @ C/5; 324 cells GNB Industrial Battery, Cooperative (now Energy United) cell now Exide Battery BESS, Statesville, NC, USA Berliner Kraft- und Licht Frequency Regulation 1987-1995 8.5 MW in 60 14 MWh Lead-acid, flooded 7,080 cells in 12 parallel Hagen OCSM cells (BEWAG) Battery System, and Spinning Reserve min of frequency cell strings of 590 cells each; Berlin, Germany regulation; 17 Cell size: 1,000 Ah MW for 20 min. of spinning reserve

Southern California Edison Several “demo” 1988-1997 Energy: 40 MWh Lead-acid, flooded 8,256 cells in 8 parallel Exide Batteries GL-35 cells Chino Battery Storage Project, modes including load- 14 MW cells strings of 1032 cells CA, USA leveling, transmission each; Cell size: 2,600 Ah line stability, local VAR control, black start. Puerto Rico Electric Power Frequency control and 11/1994-12/1999 20 MW 14 MWh Lead-acid, flooded 6,000 cells in 6 parallel C&D Battery Authority (PREPA) Battery spinning reserve cell strings of 1000 cells System, Puerto Rico each; Cell size: 1,600 Ah PQ2000 installation at Power Quality, 1996-2001 2 MW 55 kWh Lead-acid 2000 Low-Maintenance, AC Battery, acquired the Brockway Standard Uninterruptable Truck-Starting Batteries, by Omnion Power Lithography Plant in Power Supply 48 per 250 kW module, Engineering in 1997, in Homerville, Georgia, USA 8 modules per 2 MW turn acquired by S&C PQ2000 system Electric in 1999 Metlakatla Power and Light Voltage regulation 1997-present 1 MW 1.4 MWh Valve regulated 1,134 cells/378 ea., GNB Industrial Battery, (MP&L), Alaska, Battery and displacing diesel lead-acid 100A75 modules in 1 now Exide Technologies, System, Alaska, USA generation Absolyte IIP string and General Electric Golden Valley Electric VAR Support, 9/19/2003-present 27 MW 14.6 MWh Nickel/cadmium 4 strings of 3,440 cells ABB and Saft Association (GVEA) Fairbanks, spinning reserve, type SBH920 cells each, for a total of 13,760 Alaska, USA power system cells stabilization AEP Sodium Sulfur Substation upgrade 2006-present 1.0 MW 7.2 MWh Sodium/Sulfur 50 kW NAS battery NGK Insulators LTD Distributed Energy Storage deferral modules, 20 ea (battery)/ S & C Electric System at Chemical Station, Co. (balance of system) N. Charleston, WV, USA Long Island, New York Bus Load Shifting 2008-present 1.2 MW 6.5 MWh Sodium/Sulfur 20 ea. 50 kW (60kW NGK Insulators LTD Terminal Energy Storage peak) NAS battery (battery)/ABB Inc. System, NY, USA modules (integration and balance of system) Vanadium-Redox Battery Peak Shaving 2000-present 3 MW 800 kWh Vanadium-Redox 50 kW Sumitomo battery Sumitomo Electric at the Sumitomo Densetsu modules Industries (SEI) of Osaka, Office, Osaka, Japan Japan Pacificorp Castle Valley, Utah Distribution line March 2004- 250 kW 2 MWh Vanadium-Redox 50 kW Sumitomo battery VRB Power Systems Vanadium-Redox Battery upgrade deferral, present Flow Battery modules, 250 kW for 8 (purchased by Prudent (VRB) System, Utah, USA voltage support hours Energy Co., Beijing, China in 2009)

50 The Electrochemical Society Interface • Fall 2010 applications. The one application that generated the most interest centered on powering electric vehicles (EVs). However, the EV market was very slow to develop, and with the handicap of elevated temperature operation, support for most of the developers of the sodium-beta battery technologies was terminated. The dominant organization that is presently developing and commercializing the sodium/sulfur technology is a Japanese collaboration between NGK Insulator, Ltd., and Tokyo Electric Power Company (TEPCO), that started in 1984.10 Their goal is to develop cells with sufficient energy capacity for use in utility-based load- leveling and peak-shaving applications (a) that require up to an 8-hr discharge period. The critical technology for such cells involved the manufacture of large diameter beta-alumina tubes of very high quality and precise dimensions. Battery-level components include mechanical supports for the cells, a thermal management system (incorporating the thermal enclosure) to ensure that each cell is maintained at a relatively high temperature (e.g., for Na/S from 300°C to 350°C), electrical interconnects (cell-cell, cell-module, module-battery), possibly cell-failure devices, and safety-related hardware (such as thermal fuses). Batteries are assembled by connecting cells into series and series-parallel arrays to produce the required battery voltage, energy, and power. Electrical heaters are installed within the enclosures to initially warm the cells and then to offset heat loss during periods while the battery is at temperature but idle. Normally, extra heat is not required during regular (b) discharging and charging due to ohmic heating and chemical reaction effects. As discussed above, stationary applications represent a very promising Fig. 1. NGK stationary-energy-storage batteries: (a) the 50 kW modular battery component; and (b) use for the sodium/sulfur technology an integrated 500 kW/ 4 MWh demonstration battery system that uses 10 of these modular batteries, primarily because of its small relative operating since June 1998, and still in use as of January 2010. footprint (high energy density), excellent electrical efficiency if routinely Yuasa built and operated the first large Flowing Electrolyte Batteries used, integral thermal management, sodium/sulfur battery, an integrated 1-MW 8-MWh system, in the early lack of required maintenance, and A flow battery is a form of rechargeable 1990s that contained 26,880 cells.12 This cycling flexibility. The developers have battery in which electrolyte containing effort was part of the Japanese national adopted a similar design approach for one or more dissolved electroactive research program called the Moonlight their battery systems that involves the species flows through an electrochemical Project. Battery performance was use of self-contained modules, each with cell that converts chemical energy demonstrated in a utility load-leveling 10 to 50 kW of power and 50 to 400 directly to electricity. (Ed. Note: For a application. Their program reached kWh of energy. That is, independent more detailed discussion of redox flow the proof-of-concept stage, but was battery-level modules are manufactured battery configurations and chemistries, terminated.13 that consist of various series-parallel see the article on “Flow Batteries” in this The NGK modular concept and configurations of cells within a thermal issue of Interface). Additional electrolyte its implementation, which has enclosure. The battery itself is then is stored externally, generally in tanks, been successfully fielded in several constructed by connecting these and is usually pumped through the cell applications, including those described modules in a series-parallel arrangement (or cells) of the reactor, although gravity in Table I, are pictorially shown in Fig. 1, (often in a common structure) to give feed systems are also known. Flow which shows one of the NGK modules the desired voltage, energy, and power. batteries can be rapidly “recharged” along with an integrated system that The resultant battery is combined with a by replacing the electrolyte liquid (in contains these 50-kW modules. power-conversion system and controller a similar way to refilling fuel tanks for Table II describes fielded sodium/ to form an integrated facility that can be internal combustion engines) while sulfur systems with an accumulated connected to an electrical system (either simultaneously recovering the spent 11 installed capacity of 365 MWh that have utility or customer side). material that would be “recharged” in a been deployed world-wide using NGK separate step. technology.

The Electrochemical Society Interface • Fall 2010 51 Doughty, et. al. (continued from previous page)

Table II. Na/S battery projects as of december 2009. (Courtesy of NGK.) Name of Developer Country Location KW Start of Operation/Status TEPCO (Tokyo Electric Power Company) Japan Many locations around Tokyo 200,000 As of the end of 2008 (approx.) HEPCO (Hokkaidou Electric Power Company) Japan Wakkanai City, Hokkaido 1,500 Feb. 2008

Other Japanese Electric Companies Japan Many locations other than 60,000 As of the end of 2008 Tokyo area (approx.) JWD (Japan Wind Development Co., Ltd.) Japan Rokkasho Village, Aomori 34,000 Aug. 2008 AEP (American Electric Power) USA Charleston WV, Bluffton OH, 11,000 4 sites except for Presidio: July 2006~Jan. 2009; Milton WV, Churubusco IN, Presidio: Shipped in Nov. 2009 Presidio, TX NYPA (New York Power Authority) USA Long Island, NY 1,000 April 2008 PG&E (Pacific Gas and Electric Company) USA Not decided 6,000 Shipped in 2008 Xcel USA Luveme, MN 1,000 Nov. 2008 Younicos Germany Berlin 1,000 July 2009 Enercon Germany Emden, Lower Saxony 800 July 2009 EDF France Reunion Island 1,000 Dec. 2009 ADWEA (Abu Dhabi Water & Electricity UAE Abu Dhabi 48,000 Partially operated Authority) Total 365,300

The major advantage of this battery is kV transmission line and substation in Acknowledgments that power and energy are not coupled an environmentally sensitive area. The in the same way as other electrochemical system cost $1.3 M to build and install, This article relies heavily on a chapter systems, which gives considerable design while the new transmission facilities are that will appear in The Handbook of latitude for stationary applications. expected to cost over $5 M. The system Batteries-Fourth Edition, T. Reddy, Ed., Additional advantages are good specific was installed in late 2003 and became entitled “Batteries for Electrical Energy energy and recharge efficiency, low operational in March, 200416 (see Fig. 2). Storage Applications,” (in press).17 environmental impact, and low cost. This was the first VRB system installed The disadvantages of this battery in North America. Prudent Energy Inc., About the Authors technology are system complexity and based in Beijing, China, purchased high initial self-discharge rate. VRB Power Systems in early 2009 and Daniel H. Doughty is President of Battery Work on developing flow batteries continues development of these systems. Safety Consulting Inc. in Albuquerque, started with the invention of the zinc/ 14 NM. His interests include failure analysis, chlorine hydrate battery in 1968. This Conclusion advanced materials, and high energy system was the subject of development battery designs that provide improved for EV and electric utility storage Electrical energy storage using battery safety. He is also active in applications from the early 1970s to the batteries is continuing to evolve development of standard battery safety late 1980s in the United States, and from technologically, and is increasingly tests. He may be reached at dhdoughty@ 1980 to 1992 in Japan. Most work on being accepted as a viable and batterysafety.net. zinc/chlorine batteries stopped at that potentially revolutionary resource time, but recently has been restarted. which could fundamentally change Paul Butler is presently manager of Currently there are two main types of the way electricity is generated and the Joint DoD/DOE Munitions Program flowing electrolyte batteries that are used. More and more, battery storage at Sandia National Laboratories. He is under development: zinc/bromine is being considered for integration active in the research and development and vanadium-redox. A comparison of with renewable systems to increase the of munitions technologies as well as flowing electrolyte batteries for utility 15 availability and value of those resources. advanced power sources. He may be applications has been published. The use of a single storage facility in reached at [email protected]. The vanadium-redox battery (VRB) multiple applications for utility grid technology is continuing to be developed systems is also expanding and becoming Abbas Akhil is a Principal Member and installed (see Table I). Efforts are recognized for its value. As the cost of of Technical Staff at Sandia National focused on improved efficiency by energy storage systems decreases and Laboratories in Albuquerque, NM. He reducing self-discharge losses and on their reliability increases with improved works in the Energy Infrastructure and lower cost electrode structures. Self- technologies, these trends are likely to Distributed Energy Resources Department, discharge is being addressed by only accelerate and make battery storage an and is actively engaged in the engineering pumping electrolyte through the essential part of the electricity delivery and operation of advanced energy storage electrochemical stacks when necessary system. systems projects. He has over 30 years due to the magnitude of the load. These experience in electric utility and energy efforts are continuing. storage systems engineering. The PacifiCorp VRB in Castle Valley, UT, is a 250 kW, 2 MWh system that Nancy H. Clark is the Project Manager of was installed to defer for at least four Energy Storage Programs for the DOE ESS years the installation of a major new 69 Program-Sandia National Laboratories.

52 The Electrochemical Society Interface • Fall 2010 3. J. M. Eyer, J. J. Iannucci, and G. P. Corey, “Energy Storage Benefits and Market Analysis Handbook, A Study for the DOE Energy Storage Systems Program,” Sandia National Laboratories, SAND2004-6177 (2004). 4. J. McDowell, “Lithium-Ion Tech- nologies – Gaining Ground in Electricity Storage,” 2008 Energy Storage Association Annual Meeting, Orange, CA, May 20-21, 2008,. 5. K. Nakamura, M. Shiomi, K. Takahashi, and M. Tsubota, J. Power Sources, 59, 153 (1996). 6. T. Hund, M. Clark, and W. Baca, “Testing and Evaluation of Testing and Evaluation of Energy Storage Devices,” DOE Energy Storage Systems Research Program Annual Peer Review, http://www.sandia.gov/ ess/Publications/Conferences/2008/ PR08_Presentations/hund_snl.pdf. 7. J. Sudworth and R. Tilley, The Sodium/ Sulfur Battery, Chapman and Hall, London (1985). 8. D. Linden and T. Reddy, Handbook of Batteries, 3rd Edition, McGraw-Hill (2003). 9. J. Coetzer, J. Power Sources, 18, 377 (1986). 10. T. Oshima and H. Abe, in Proc. 6th Int. Conf. on Batteries for Utility Energy Storage, Wissenschaftspark Gelsenkirchen Energiepark Herne, Germany (1999). 11. A. Nourai, “Installation of the First Distributed Energy Storage System (DESS) at American Electric Power (AEP), A Study for the DOE Energy Fig. 2. Exterior and interior views of the 2MWh VRB system at Castle Valley, UT. Storage Systems Program,” Sandia National Laboratories Report Since 1989 Nancy has been a project program at Sandia. This includes DER SAND2007-3580. lead on DOE Energy Storage Programs. work for the DOE and military customers, 12. E. Nomura, et al., in’ Proc. 27th IECEC The projects have covered a wide range collaborative projects with utilities and Conf., 3:3.63–3.69 (1992). of advanced energy storage technologies industry in design and testing at the 13. A. Araki and H. Suzuki, in Proc. 6th including zinc bromine, zinc air, nickel Sandia Distributed Energy Technologies Int. Conf. on Batteries for Utility metal hydride, lithium ion, advanced lead Laboratory. Boyes has been with Sandia Energy Storage, Wissenschaftspark acid batteries, composite flywheels, and for 32 years, managing programs and Gelsenkirchen Energiepark Herne, ultra capacitors. She has managed millions projects for the last 20 of those years. Prior Germany (1999). of dollars for the Department of Energy to joining the Energy Storage Program he 14. P. C. Symons, U.S. Patent 3,713,888 programs over the past 20 years. Most was involved in the design, construction, (1973). recently she managed the DOE program and project management of multi-million 15. C. Lotspeich, “A Comparative that delivered the first advanced energy dollar pulsed power test facilities and Assessment of Flow Battery storage technology used as part of the equipment. Technologies,” EESAT 2002, San electricity infrastructure of a public utility. Francisco, CA, April 15-17, 2002. Based on the success of that program, References 16. W. Steeley, “VRB Energy Storage she is managing a follow-on program for Voltage Stabilization - Testing that will add three more systems to the 1. A. A. Akhil, H. Zaininger, J. Hurwitch, and Evaluation of the PacifiCorp utility’s infrastructure. Dr. Clark is well and J. Baden, “Battery Energy Vanadium Redox Battery Energy known in the energy storage field as the Storage: A Preliminary Assessment Storage System at Castle Valley, conference organizer for two international of National Benefits (The Gateway Utah,” EPRI Report 1008434, electrical energy storage applications and Benefits Study),” Sandia National Technical Update (March 2005). technologies conferences. Laboratories, SAND93-3900 (1993). 17. A. A. Akhil, J. D. Boyes, P. C. Butler, 2. P. C. Butler, “Battery Energy Storage and D. H. Doughty, “Batteries John D. Boyes is the Manager of the for Utility Applications: Phase I – for Electrical Energy Storage Energy Storage and Distributed Energy Opportunities Analysis,” Sandia Applications,” in The Handbook of Resources Departtment at Sandia National National Laboratories, SAND94- Batteries, Fourth Edition, T. B. Reddy, Laboratories. For the past twelve years, John 2605, 1994; and P. Butler, J. L. Miller, Ed., McGraw-Hill Professional Boyes has managed the U.S. Department and P. A. Taylor, “Energy Storage Publications, New York, NY (2010). of Energy funded Energy Storage Systems Opportunities Analysis Phase II Final Program at Sandia National Laboratories, Report, A Study for the DOE Energy which develops utility scale electricity Storage Systems Program, Sandia storage systems. He is also responsible National Laboratories, SAND2002- for the Distributed Energy Resources 1314 (2002). The Electrochemical Society Interface • Fall 2010 53