Energy-Efficient Technologies for the Dismounted Soldier (1997) / Chapter Skim
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3 Energy Sources and Systems
3 Energy Sources and Systems
Pages 28-45
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From page 28... ...
Numerous studies have recognized the need for major advances in battlefield power technology (Space Power Institute, 1990, 1992a, 1992b, 1994~. Mobility for the dismounted soldier demands energy storage density in a compact package that can satisfy power requirements of up to 100 W
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From page 29... ...
The Army can optimize its use of energy and power by: employing more energy-dense power sources using systems optimized for minimal energy and power requirements maximizing the use of available energy (e.g., use of automated controllers and chargers that carefully meter energy and place noncritical functions in sleep mode while maintaining power for critical functions) To date, fueled energy systems are low in specific energy and specific power except when they are used for long run times when fuel mass dominates system mass.
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From page 30... ...
FIGURE 3-l Specific energy and specific power for various energy storage media. In general, the higher the specific power, the lower the specific energy.
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From page 32... ...
The dismounted soldier will probably ultimately use rechargeable batteries that have higher specific power and energy (which would match or exceed those available from current primary batteries) coupled with "personal" chargers.
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From page 33... ...
Sections include rechargeable batteries, fueled systems, nuclear energy sources, human-powered systems, photovoltaic technology, thermophotovoltaics, electrochemical capacitors, and hybrid systems. Rechargeable Batteries Although battery technology is relatively mature (Cairns, 1992; McLarnon and Cairns, 1989)
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From page 34... ...
in addition to silent operation and minimal thermal signature, this filet cell is free of the logistics chain associated with primary batteries because it uses hydrogen, a fuel that can be obtained directly or indirectly from many source materials. The principal by-product of hydrogen fuel cells is water.
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From page 35... ...
Excellent progress is being made toward solving both of these problems. In terms of technology demonstration, direct methanol fuel cells are three to five years behind the hydrogen-fileled PEM fuel cells.
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From page 36... ...
By 2015, prototype microturbines machined from silicon may have been developed, which will provide 1,000 Wh in a package weighing as little as 0.25 kg. if this high risk effort is successful, it would provide extremely attractive specific power and energy for the dismounted soldier.
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From page 37... ...
The most interest is being shown at present in using AMTEC for deep space probes where the heat source is nuclear. The principle of energy conversion used in the AMTEC is independent of the heat source and, because modest laboratory efficiencies have been obtained, it is a good candidate for Army applications in the 50 to 500 W range.
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From page 38... ...
Because of possible health and environmental hazards, the problems inherent in using nuclear materials on a battlefield are formidable and could only be addressed in a large and expensive program. This is unfortunate because deep space probes using nuclear sources have demonstrated lifetime and reliability characteristics far exceeding those of other energy sources.
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From page 39... ...
it is possible through sophisticated energy management and through low power electronics to reduce the dismounted soldier's demand for energy to a level at which it may be possible for the soldier to produce enough electrical power to provide a substantial amount of the electrical energy he or she needs. This would require converting to electricity some of the energy expended by the soldier during everyday activities.
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From page 40... ...
Planar arrays with specific power as high as 60 W/kg have been produced for space applications. In general, the conversion efficiency is a function of the cell type and ranges from ~ O to 30 percent.
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From page 41... ...
Electrochemical Capacitors Traditional capacitors, in general, have high specific powers but are incapable of high specific energies. Conversely, batteries have high specific energies but are incapable of extremely high specific powers.
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From page 42... ...
Hybrid systems combine the advantages of very high specific energy sources capable of maintaining the base load with very high specific power sources capable of providing peak power when needed. This configuration will greatly enhance power and energy capabilities and will require small portable package.
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From page 43... ...
Heat engines in the form of small internal and external combustion devices have been investigated as a way to provide mechanical energy directly to a compressor. Internal combustion devices could be used, but they have acoustic and thermal signatures and produce significant vibrations.
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From page 44... ...
Key Research Issues Microclimate cooling presents the most challenging power problem for the dismounted soldier. As mission times increase, the mass of battery powered systems quickly escalates to values not compatible with the soldier's Toad.
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From page 45... ...
High specific power, high specific energy, secondary batteries, and electrochemical capacitors will be essential for future dismounted soldier systems. Missions of more than ~ kWh will require nonbattery power systems/sources or recharging.
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