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Appendix D: Energy and Power Materials
Pages 251-284

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From page 251...
... In the main body of this report, the committee attempts to show that some material improvements can affect several technologies. Batteries and fuel cells will both benefit from improved electrolytes and better methods to tailor electrochemical interfaces.
From page 252...
... power sources. These include differences in required power and energy levels, in temperature operating range, in the need for shock resistance, in longevity requirements, and in reliability levels.
From page 253...
... Compared to other forms of electrical energy storage, capacitors are lower in energy density SonobuoyS Impulse 0 O Sidewinder CL)
From page 254...
... EXPLOSIVES AND PROPELLANTS Explosives Many of the key chemical explosives of military interest today were first synthesized in the late 1 800s and, as with structural materials, moving from laboratory curiosity to general application of energetic materials has often taken 20 to 30 years, as shown in Table D-1 (Federoff, 19601. Important technological parameters for high explosives are energy release/ reaction propagation rate; energy density; and resistance to accidental explosion (insensitivity)
From page 255...
... Unless they are to carry a disproportionate share of mass in weapons and explosive power, achieving the same energy on target will require higher energy density materials (HEDM)
From page 256...
... SOURCE: Ullrich, G.W., director, Weapons Systems, Office of the Secretary of Defense, Advanced Energetic Materials: Introduction and Overview, presented to the Committee on Advanced Energetic Materials and Manufacturing Technologies, National Research Council, Washington, DC, July 31, 2001. Propellants Propellants burn without exploding and contain all the oxygen they need for combustion (Alchavan, 19981.
From page 257...
... 4Goldwasser, J., "Navy Energetic Materials Science and Technology Programs," briefing presented to the Committee on Advanced Energetic Materials and Manufacturing Technologies, National Research Council, Washington, DC, July 31, 2001.
From page 258...
... Making novel energetic materials available in large quantities for military use will require improved means for synthesis and 5Wilson, W.H., munitions directorate, Air Force Research Laboratory, Eglin Air Force Base, "Advanced Energetic Materials Research," paper presented to the Committee on Advanced Energetic Materials and Manufacturing Technologies, National Research Council, Washington, DC, July 31, 2001 .
From page 259...
... The panel recognizes that new electrochemical propulsion and power systems employing fuel cells are in various stages of design and development and it bel loves that thei r development as outl i ned i n Chapter ~ is essential for the DoD applications of 2020. However, it also appears that current hydrocarbon military fuel families (jet fuel and diesel fuel)
From page 260...
... Concurrent efforts will be made to improve civilian transport efficiency by way of leaner burning internal combustion systems, hybrid electric vehicles, fuel cells, greater use of mass transportation, and telecommuting. The environment will drive changes in petroleum-based fuel formulation to reduce volatile organic compounds, N OX, particulates, and greenhouse gas emissions.
From page 261...
... Other advances that relate to methods for on-board reforming of logistic fuels and for storing fuels like hydrogen are discussed in the section on fuel cells in Chapter 4. FUEL CELLS Description Fuel cells are devices that directly convert chemical energy into electrical energy and, because they do not involve combustion, are not Carnot-limited.
From page 262...
... High temperatures, as employed for molten carbonate and solid oxide fuel cells, generally ensure that reactions are rapid and a variety of hydrocarbon fuels can be used directly in the fuel cell. However, start-up times can be very long, and there is a limited number of (usually expensive)
From page 263...
... In particular, (1 ) they are highly efficient, easily 45 percent for high-temperature fuel cells with even greater efficiencies in hybrid systems; (2)
From page 264...
... Today's system costs range from ~$4,500/kW for phosphoric acid and molten carbonate fuel cells to over $1 0,000/kW for solid oxide, polymer electrolyte, and alkali fuel cells. In the Partnership for the Next Generation of Vehicles program (now abandoned)
From page 265...
... Wh i le th is approach has demonstrated success, limitations due to electrolyte solubility in water and degradation under fuel cell operating conditions are yet to be addressed (Haile et al., 20011. In the case of molten carbonate, alkali, and phosphoric acid fuel cells, it is fair to conclude that further significant advances in the electrolyte material, particularly in ionic conductivity, are unlikely.
From page 266...
... .8 The low operation temperatures of these fuel cells, along with the chemically aggressive nature of the electrolyte, further limit electrocatalyst choices to costly precious metals, except in alkali fuel cells. Inadequate anode catalyst performance is also what limits the use of diesel fuels in higher temperature (SOFC and MCFC)
From page 267...
... It has long been believed that the use of hydrocarbon fuels in solid oxide fuel cells requires an internal reforming reaction step, in which water and fuel react in the vicinity of the fuel cell anode to produce CO2 and H2, and that the hydrogen so generated is then consumed electrochemically to produce electricity. Groups at Northwestern University (Murray et al., 1999)
From page 268...
... Methane reformers are the most mature technology; gasoline reformers are under rapid development in the civilian automotive sector. For DoD applications, reformers that process diesel fuels for lower temperature fuel cells or high-temperature fuel cells that use diesel fuels are essential.
From page 269...
... Given the potential of such reactors to solve the daunting fuel problem for fuel cells, additional efforts in this direction are needed. An entirely different strategy for providing hydrogen for fuel cells is the use of nonconventional fuels like ammonia, hydrazine, or sodium borohydrate.
From page 270...
... Useful TE materials must not only exhibit high ZT over a wide temperature range but must also be compatible with both donor and acceptor doping. Although the two legs could be made of unrelated n- and p-type compounds, complications with material compatibility and device design can arise if their properties (coefficient of thermal expansion, thermal conductivity, electrical conductivity, etc.)
From page 271...
... U n I i ke many technological solid-state electronic materials, in which simplicity in composition and structure and extreme crystalline order and purity are sought, TE materials are more likely to have complex composition, elaborate crystal structure, and even disorder, all features that may lower lattice thermal conductivity without sacrificing electrical conductivity and thermopower. Moreover, a single material is unlikely to exhibit high ZT over the entire temperature range of interest.
From page 272...
... If sufficiently high efficiencies could be obtained, these devices would be revolutionary for DoD in simplifying logistics and modifying energy resupply requirements. In theory, solar radiation could supply electricity and also make it possible to produce hydrogen from available water to fuel hydrogen fuel cells.
From page 273...
... ELECTRIC POWER GENERATION FOR FUTURE DOD SYSTEMS: EFFECTS OF ELECTRIC PROPULSION IN SHIP DESIGN Platform propulsion and support using more electric systems is of importance to the Army, Navy, and Air Force. The consumption of electric power by elements of DoD will likely increase significantly over the next 25 years.
From page 274...
... In January 2000 the Secretary of the Navy announced that the next generation of warships would be propelled by an electric drive system. Advantages of Electric Propulsion in Ship Design Compared to the standard mechanical drive system that uses reduction gears, there are many advantages to an integrated electric propulsion system: 274
From page 275...
... . Commonality allows major pieces of electric propulsion equipment to be used in virtually every warship in the U.S.
From page 276...
... One way the marine industry is attempting to mitigate the power density problem is by raising the power levels associated with the propulsion system, but this raises a myriad of issues not previously experienced by marine propulsion engineers. The potential power required of DoD weapon systems only exacerbates the problem.
From page 277...
... Integrated platform electrical power and propulsion systems will also require improved modeling and analytic tools and advanced algorithms to model effects and interactions among systems and material characteristics in this highly complex environment. Detailed system modeling tools must reflect integrated power-system control and transient response as well as modeling local components.
From page 278...
... This section examines the major energy sources: fossil fuels and nuclear energy. TABLE D-3 Goals for Future Armor Areal Density Areal Density (Ib/ft2)
From page 279...
... was used for actual support of military operations and training, with the remainder used for buildings and nontactical vehicles. Major energy sources were traditional fuels for military platforms (e.g., jet fuel, diesel)
From page 280...
... Wind and hydropower are unlikely to provide primary power for major platforms. Novel materials can affect many of these modes and may reduce DoD energy consumption through more efficient propulsion technologies; lightweight, high-specific-stiffness and strength structures; vehicle armor approaches that do not rely solely on areal density for protection but use lighter materials and novel protection schemes to reduce weight; higher-energy-density batteries, and fuel cells capable of direct electrochemical conversion; improved fuels; and smart electronics that use energy more effectively.
From page 281...
... This directly affects DoD strategy for further acquisition of nuclear-powered assets. Indeed, only the unique requirements of aircraft carriers and submarines justify the cost of incorporating nuclear propulsion plants today.
From page 282...
... Feasibility studies of thermonuclear-PV direct energy conversion being conducted at the Knoll's Atomic Power Laboratory show the clear potential of this technology. As noted elsewhere in this report, fuel cells are considered a desirable energy source for future defense systems.
From page 283...
... 1999. Annual report to Congress on Federal Government Energy Management and Conservation Programs for Fiscal Year 1997, U.S.
From page 284...
... 2000. A lowoperating-temperature solid oxide fuel cell in hydrocarbon-air mixtures.


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