Reducing the Logistics Burden for the Army After Next Doing More with Less (1999) / Chapter Skim
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4 Fuel and Energy
4 Fuel and Energy
Pages 48-63
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From page 48... ...
An AAN battle force to minimize the dependence on resupplied energy' must be as energy efficient as possible. There are three logical approaches for the battle force to meet its energy needs: to increase the total energy supply, to decrease the total energy demand, or to increase the efficiency of energy utilization and management.
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From page 49... ...
In this high-risk, but very high-payoff, strategy, stored energy in the form of nuclear fuel would be shipped to the staging area where lightweight, modular, transportable nuclear power plants would convert it to electrical energy. She electrical energy would then be converted by electrolysis of locally obtained water to stored energy in hydrogen, and hydrogen would replace petroleum fuels as the principal battlefield fuel for the AAN force.
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From page 50... ...
to decrease the volume required to store a given weight of hydrogen "fuel." Significant progress has been made in the small-scare storage of hydrogen, at much Tower pressures than those used for compressed gas, to replace a heavy battery with an efficient proton exchange membrane (PEM) fuel cell.
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From page 51... ...
Nuclear reactors as energy sources are not viewed favorably in the United States for safety, economic, and environmental reasons. Yet the safety concerns are not insurmountable, and the economics of supplying energy for an AAN battle force are different from those of a commercial power plant supplying the national electrical grid.
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From page 52... ...
If AAN battlefield systems use fuel cells (which convert stored energy in a chemical fuel to electricity) as their primary energy conversion device, hydrogen would be a convenient battlefield fuel because the proximal fuel for fuel cells is hydrogen (see Box 4-1~.
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From page 53... ...
The AAN battle force's mission would have to last 19 days for this weight burden to break even with the strategic logistics burden of transporting diesel fuel. The break-even point improves considerably if one anticipates that a more efficient electrolyzer can be developed based, perhaps, on the same technology as fuel 53 BOX 4-1 Fuel Cells A primary advantage of using a fuel cell over a combustion engine to power an electrical generator is that the fuel cell can convert more of the stored energy in the fuel to electrical energy.
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From page 54... ...
First, a realistic approach to increasing energy supply while decreasing logistics burdens must take into account the entire system, from the materiel that must be transported to the staging area (the strategic logistics burden) to how AAN vehicles are powered and refueled (the operational and tactical burdens)
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From page 55... ...
Idling discipline, towing vehicles, route selection, and fuel economy mandates during procurement were identified in two Army Science Board studies (ASB, 1984; ASB, 1987) as areas for reducing fuel consumption.
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From page 56... ...
If the specific application for the component involves moving parts, where inertial forces become important, a more precise design parameter derived from the yield strength would be (~3 / p.
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From page 57... ...
Information Resources for Improving Materials Selection A second obstacle to the Army's use of lightweight materials is the lack of awareness by system designers of the existence and properties of new alloys and other advanced composite materials. Materials that are not known include materials developed secretly by the former Soviet Union, such as aluminum foam and explosive armor coatings.
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From page 58... ...
Innovative materials solutions that combine reduced system weight with increases in system performance will reduce AAN logistics burdens. System Optimization of Protection and Other Vehicle Weight Reduction Factors Protection of an AAN combat vehicle and crew must be assessed at the system level, along with other system performance goals, such as cross-country mobility, fuel efficiency, and lethal efficiency (i.e., one round, one hit, one kill)
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From page 59... ...
considerations for protective systems for AAN combat vehicles are discussed more fully in Appendix D.) EFFICIENT ENERGY MANAGEMENT The preceding discussions on increasing energy supplies and decreasing energy demands have illustrated the advantages of using a systems engineering approach to determine the best alternatives for AAN mission scenarios.
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From page 60... ...
, would have better fuel economy than a prime-mover-only power plant on an AAN battlefield. As far as the committee could determine, the Army has not yet determined the classes of vehicles, much less characterized the duty cycle (or cycles)
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From page 61... ...
Although these preliminary considerations are based on rough approximations and general engineering experience, they imply that the fuel economy advantage often assumed for hybrid vehicles cannot be taken for granted in the AAN context. The point of this argument is not that hybrid vehicles should be ruled out but that systematic, detailed analyses that incorporate the relevant factors on duty cycle and nonrecoverable energy losses should be used to assess the potential benefits and make a rational decision.
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From page 62... ...
Assuming that the prerequisite investigations into nuclear energy as a primary source and hydrogen as a storable battlefield fuel are successful, the Army should investigate an electrochemical process for converting electrical energy to fuel energy in hydrogen (reverse of a hydrogen fuel cell)
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From page 63... ...
Whether an electric hybrid power plant improves the fuel economy of a vehicle depends on the vehicle duty cycle. Based on the qualitative descriptions to the committee of how an AAN battle force would operate and a general automotive engineering rule of thumb on the kind of duty cycle in which a hybrid power plant improves overall fuel economy, it seems unlikely that a hybrid vehicle would reduce fuel consumption in an AAN operation.
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