Backup power

A fuel cell can be used for any applications that require electricity (and heat). It was first used in manned spacecraft in the United States. Currently, the major markets for fuel cells are stahonary, transportation, and portable power. This chapter will discuss its application for stationary power. Stationary power includes backup power and primary power. 

Proton exchange membrane fuel cells (PEMFCs) do not have the problems associated with batteries and diesel generators, and are believed to be the ideal backup power. The following discussion will focus on telecommunications backup power applications. 

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If possible comparisons are focused on energy systems, nuclear power safety is also estimated to be superior to all electricity generation methods except for natural gas (30). Figure 3 is a plot of that comparison in terms of estimated total deaths to workers and the pubHc and includes deaths associated with secondary processes in the entire fuel cycle. The poorer safety record of the alternatives to nuclear power can be attributed to fataUties in transportation, where comparatively enormous amounts of fossil fuel transport are involved. Continuous or daily refueling of fossil fuel plants is required as compared to refueling a nuclear plant from a few tmckloads only once over a period of one to two years. This disadvantage appHes to solar and wind as well because of the necessary assumption that their backup power in periods of no or Httie wind or sun is from fossil-fuel generation. Now death or serious injury has resulted from radiation exposure from commercial nuclear power plants in the United States (31). 

A central location where instmment leads are short is preferred. In modem faciHties with distributed control systems, all units are controUed from a central control room with few operators. Only a few roving operators are available to spot trouble. It is desirable to deep process equipment a minimum of 8 m away from the control room. Any equipment and hydrocarbon-containing equipment should be separated by at least 15 m if possible. Most control rooms are designed with blastproof constmction and have emergency backup power and air conditioning. The room is pressuri2ed to prevent infusion of outside air that may have hydrocarbon content in the explosive range. 

Adjustable speed motor driven feedwater pumps and high-capacity control rod drive pumps with backup power improve the safety margin by improving correct operator response to non-routine events. 

The control and snpervision of a snppression system is achieved rising an electrical power/control unit with 24-horir (minimum) standby battery backup power. The unit supplies sufficient energy to accomplish the following (NFPA69 1997) ... 

The battery, which features a high (3.6 V) operating voltage and wide operating temperature range (-55 to 85 °C) can serve as a memory backup power source. Table 9 shows their specifications (381. 

Lithium-vanadium oxide rechargeable batteries were developed as memory backup power sources with high reliability and high energy density. 

The battery features an operating voltage of 1.5-3 V. The energy density of the VG2025 (diameter 20.0 mm, height 2.5 mm) is 96 Whl-1. It can serve as a memory backup power source. Table 14 shows the specifications of the batteries [55],... 

The battery life in some laptop computers is a consideration. Some laptop batteries may last long enough to perform calibration and application some may not. Additionally, there may be unforeseen circumstances that may require longer access to the laptop or that may cause premature battery failure. In order to ensure that data are not lost, a source of backup power, such as a spare battery or an adapter that plugs into the vehicle cigarette lighter, should be available. 

The term rechargeable consumer product (a) means a product that, when sold retail, includes a regulated battery as a primary energy supply and which is primarily intended for 1 kW personal or household use, but (b) does not include a product that uses only a battery as a sole source of backup power for memory or program instruction storage, timekeeping, or any other similar purpose that requires uninterrupted electrical power, in order to function if the primary energy supply fails or fluctuates momentarily. 

Laboratories designed for the handling of toxic materials normally maintain reduced pressures in the rooms and hallways, relative to the pressure outside the buildings. Hoods should therefore be fitted with antibackflow valves to avoid sucking the contents of the ductwork into the laboratory in the event of a power failure. Backup power provided in 15 seconds does not prevent this phenomenon, even if the hoods and airhandlers are designed to restart automatically. 

Other Recirculation or exhaust air from chemical areas is prohibited. No connection between chemical areas and other areas through ventilation system is permitted. Emergency backup power is necessary. Hoods should be tested at least semiannually or after modification or maintenance operations. Operations should be performed 20 centimeters inside hood face. 

Plug Power, a Latham, NY, based manufacturer of stationary hydrogen fuel cell generator units for backup power has developed a hydrogen fueling station with the help of Honda. This station uses a small steam reformer that extracts hydrogen fuel from natural gas using steam. The steam reformer has been reduced to half the size of the previous version. 

The Department of Defense (DOD) Fuel Cell Demonstration Program is managed by the U.S. Army Corps of Engineers. It was begun in the mid-1990s to advance the use of PAFCs at DOD installations. Under this program, stationary fuel cells were installed at 30 facilities and locations in the Armed Services. The fuel cells are used for primary and backup power as well as heat. 

Stationary power is the most mature application for fuel cells. Stationary fuel cell units are used for backup power, power for remote locations, stand-alone power plants for towns and cities, distributed generation for buildings, and cogeneration where excess thermal energy from electricity generation is used for heat. 

Thousands of smaller stationary fuel cells of less than 10 kilowatts each have been built and operated to power homes and provide backup power. Polymer electrolyte membrane (PEM) fuel cells fueled with natural gas or hydrogen are the primary units for these smaller systems. 

Hordeski, Michael F., Emergency Backup Power Sources, The Fairmont Press , Lilburn, GA, 2004. 

For the stationary generation of heat and power the PEMFC is also in development. Fuel cell systems for combined heat and power generation mostly run on natural gas, and sometimes on biogas. Reformate is fed to the anode in these stationary systems. Only for backup power systems, which are designed for only a limited operating time, is pure hydrogen often used as fuel for the anode. 

Backup power to a load normally connected to the local utility... 

Tanks covered by these requirements can be fabricated in cylindrical or rectangular configurations. The standard covers secondary contained tanks, either of dual-wall construction or a tank in a steel dike or bund. It also provides listings for special AST constructions, such as those used under generators for backup power. These tanks are fabricated, inspected, and tested for leakage before shipment from the factory as completely assembled vessels. 

PEM - BCHydro/Ballard Airgen 1.2 kW utility backup power system. 

The reason that solid state batteries are potentially useful is that they can perform over a wide temperature range, they have a long shelf life, and it is possible to manufacture them so that they are extremely small. Lightweight rechargeable batteries can be now be made to give sufficient power to maintain mobile phones for several days and laptop computers for several hours. They are used for backup power supplies and may eventually become useful as alternative fuel sources to power cars. 

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