Batteries for Stationary Applications

Discharge curves for a 1380-Ah, OCSM cell, at constant-power discharges of 

OCSM cells with tubular positive plates and copper negative grids have been used successfully for various stationary applications. In 1986, for example, a 

In 1995, the BEWAG battery reached the end of its service-life. During its time in service, the 14-MWh battery storage system operated successfully with virtually no problems [87]. This was a very remarkable result, as the operating conditions were severe. The battery had a capacity turnover of some 7000 times the nominal capacity, and the total energy turnover was about 100 GWh. 

Large OCSM batteries are also suitable for other utility applications. Recently, the concept of a multifunctional energy storage system, which is useful to improve the utilisation of regenerative energies, has been evaluated [88]. This system includes three different functions (i) uninterruptible power supply (UPS), (ii) improvement of power quality, and (iii) peak load assists via the use of regenerating power sources, with surplus energy from periods of low demand stored in a battery for peak-load periods (see Chapter 10). 

Two multifunetional energy storage systems, eaeh with a 1.2-MWh lead-acid battery, were installed reeently in Germany. There is one system in combination with a solar plant and another one in combination with a wind farm. The batteries consist of OCSM cells with the standard design, but modified aecording to the special demand of a multifunctional application. 

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Recently the development of Na/S batteries for car applications has been abandoned only Na/S batteries for stationary applications (load leveling) are still under development in Japan. Among the high-temperature batteries, the ZEBRA battery is the only system at present which is being commercialized for car applications. 

Li-ion batteries for stationary applications in their present form are a questionable choice as there are competing technologies that have produced more viable options for these applications for more information on competing technologies see Chap. 7 of this book. The (snbjective) list of the most promising materials for future lithium-ion batteries is listed in Table 1.11, along with the perceived obstacles to full implementation of these technologies. 

Determining the effective capacity enables us to work out the moment of EOL of a secondary battery. Generally a secondary battery, for stationary applications and for electric vehicles, is considered to be out of service when its measured capacity is less than 80% of its nominal capacity. This is a commercial or contractual notion, which does vary (e.g. 70% for stationary secondary batteries). This end-of-life capacity is called the residual capacity. 

Institute of Electrical and Electronic Engineers (IEEE). IEEE 484, Recommended practice for installation design and installation of vented lead-acid batteries for stationary applications. IEEE 2002. 

Batteries for stationary applications may use cells with flat-pasted, tubular, Plantd, or Manchester positive plates. Typical discharge curves for the flat-pasted-type stationary cell at various discharge rates at 25°C are shown in Fig. 23.38, and the effect of the discharge rate on the capacity of the cell is summarized in Fig. 23.39. Generally, the discharge rate for stationary ceUs is identified as the hourly rate (the current in Amperes that the battery will deUver or the rate hours) rather than the C rate used for other types of batteries. 

As a consequence, most battery manufacturers tried to minimize or even eliminate the antimony addition, especially in batteries for stationary applications where smaller demands are made in respect to cycle service. 

Yuasa have constructed a400kWh 50kW unit battery for stationary applications and are now working on a I MW 8MWh unit for stationary testing. 

Battery technology is one of the most rapidly developing fields in energy storage, driven by the anticipated application in electromobility, so that in the future additional competitive technologies could become available for stationary applications as well. 

MW installations. Recently there are also major efforts and some initial success in implementation of rechargeable lithium-ion technology for stationary applications. From the view point of global energy utilization and consumption, the ultimate goal for stationary batteries is power-line load leveling. 

Sonnenschein was the first company to introduce gel battery technology to the market successfully. They started in 1958 with rather small batteries for flashlights. Since that time, this technology has steadily replaced the conventional, flooded lead-acid battery in various applications [38,71,72]. Phosphoric acid addition for cycling was first introduced in 1965. Larger gel batteries with tubular positive plates were developed for stationary applications in 1978. More recently, gel batteries have been produced for starter and traction applications, and thick, flat positive plates were added for telecommunications applications. 

The degradation and aging mechanism depend on several factors [36,37]. At present the guaranteed calendar lifetime of a lithium battery ranges from 2 years (e.g. Sam) to 8 years (e.g. Ampera, Volt) depending on the car s manufacturer. An average lifetime for traction batteries of 10 years is still a development target, which have not been reached and demonstrated at a practical level. But of course, a battery can also be used below 80% of its nominal capacity. A second use phase of batteries, e.g. for stationary applications, has not been considered. 

Africa)io is a variant of sodium-sulfur technology where sulfur is replaced with a metal chloride such as NiCl2 (nickel chloride) or FeCU. It was specifically developed for applications in electric vehicles, freight transport and public transport the ZEBRA battery is more particularly intended to serve buses and utility vehicles. As with the Na-S battery, the vibrations felt in a vehicle may cause premature aging of the ceramic/metal interface. Today, such batteries are also being considered for stationary applications. 

The first part of this book (Chapters 2 to 14) concerns batteries of larger capacities that are employed as standby batteries in stationary applications, provide energy in vehicles like forklift trucks, or stabilize an electrical network like the starter battery in motor cars. Rechargeable batteries usually are the choice in such applications, since primary batteries would be too expensive for the required rather high capacity. The second part (Chapters 15 to 19) regards batteries mainly in portable applications and concerns smaller capacities. In this field primary as well as secondary batteries are employed. 

Standby batteries in stationary applications are continuously overcharged at a comparatively low voltage for two reasons ... 

Cells are assembled into batteries in many different ways. Often 2 to 10 cells are mounted in a separate battery unit, several of which may be used to form the complete battery. A typical battery is shown in Fig. 26.5. Cells in plastic containers are also assembled into batteries by putting the single cells close together on a rack or a stand and connecting them with intercell connectors. This is especially the case for stationary applications (Fig. 26.6). Cells in steel containers can be assembled in a similar way however, here the cells must be spaced from one another and insulated from the rack. 

The corrosion capacity of the positive grid can be estimated from the above flgures. The positive grid in lead-acid batteries for stationary and traction applications contains about 10g of lead/Ah (usually slightly more). This means a positive-grid weight of about 1 kg/100 Ah. With the values of Equation 6.32, the corrosion capacity is 500/100 Ah of battery capacity. The corrosion rate of 1 or 2mA/100 Ah means 8.76 and 17.52/100 Ah per year respectively. Related to the 500 Ah of the total corrosion capacity, 2-4% of the grid material would be converted into lead dioxide per year under these assumptions. 

Selection of suitable stationary or standby power batteries for the application... 

Yuasa have constructed a 400 kWh battery intended for stationary application testing. Argoime National Laboratory, US have published projected ranges and speeds for different simulated driving profiles comparing sodium-sulphur batteries with lead-acid and nickel-iron (Table 43.3). 

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