Technology for the United States Navy and Marine Corps, 2000-2035: Becoming a 21st-Century Force Volume 2: Technology (1997) / Chapter Skim
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8 ELECTRIC POWER AND PROPULSION
8 ELECTRIC POWER AND PROPULSION
Pages 230-281
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From page 230... ...
Takes a design approach in requiring modularity, commonality, and use of commercial technology for economy of scale wherever appropriate; {Advanced Surface Machinery Programs Division, Ship Research Development and Standards Group, Engineering Directorate (SEA 03R2)
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From page 231... ...
The emergence of direct electric conversion technologies, such as fuel cells, offers potential for fuel-efficient, low-emission, and low-noise sources of electrical power. Within the plan, the Department of the Navy's integrated propulsion system (IPS)
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From page 232... ...
Optimization of submarine systems will be driven by stealth, safety, power density, and other requirements that differentiate surface and undersea vehicles. Submarine power and propulsion system technologies of the future will include the following: · Very low harmonic motor controllers; · High-power-density and high-performance solid-state inverters and converters and the components thereof; Electrical substitutes for systems and components that now rely on fluid transport for energy and actuation, e.g., electric actuators, electromagnetic launchers, and thermoelectric coolers; · Motors and generators with very low acoustic and magnetic signatures, including versions that can operate submerged in seawater at high pressure; and .
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From page 233... ...
These include the following: . Pulsed-power systems including energy storage pulse-forming networks and very high power solid-state switching; · Flywheel energy storage; · High-power-density engines, including electric drive systems with a unit size of several hundred horsepower; and .
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From page 234... ...
A prime electric power source feeds directly, or via a load-leveling or storage stage, into a conditioning stage to alter the electrical parameters for optimum reliable power distribution to a load. The panel believes that the following three technologies will require special attention and support if the full potential of integrated electric power and propulsion systems is to be realized: · Power generation, including advanced fuel-efficient turbogenerator power units for continuous power and for pulsed or short-duration power generation applications and direct electrochemical and electrothermal generators such as fuel cells; · Power conditioning and distribution, including passive components, such as capacitors, inductors, and transformers, and active devices, such as power
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From page 235... ...
Technology forecasts are provided in the sections that follow. TABLE 8.1 Electric Power Technology Areas Electric Power Generation Energy Storage and Recovery as Electric Power Nuclear-electric generators Turboshaft engine generators Piston-engine generators Fuel cells H2 Other Explosive/magneto-hydrodynamic Power conditioning Bus power Slow power Fast power Primary batteries Rechargeable batteries Superconducting magnets Flywheels Pumped liquids Compressed gases Thermal storage SOURCE: Adapted from the Board on Army Science and Technology, 1993, "Electric Power Technology for Battle Zones," STAR 21: Strategic Technologies for the Army of the Twenty-First Century, National Academy Press, Washington, D.C., Table 43-1, pp.
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From page 236... ...
The mass and volume of generators in this class are half power unit and half power conditioning. The physical decoupling of power and propulsion subsystems afforded by electric drive will be a powerful enabler for compact, versatile, and powerful future ships.
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From page 237... ...
Systems with these characteristics will be required in the future, particularly for the intermediate power ranges from 50 kW up to the megawatt level. The most significant factors controlling the specific power of an integrated unit are engine rotating speeds, generator frequency, and generated voltages.
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From page 238... ...
Power densities as high as 100 kW/kg are conceivable for power conditioners when integrated-circuit fabrication techniques are used to manufacture integrated converters. Figure 8.2 shows how the operating time affects the total specific power (power/weight ratio)
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From page 239... ...
: 24,000-72,000 RPM turbine, 400-Hz power output FIGURE 8.2 Specific power versus operating time for advanced turbogenerators. SOURCE: Adapted from the Board on Army Science and Technology, 1993, "Electric Power Technology for Battle Zones," STAR 21: Strategic Technologies for the Army of the Twenty-First Century, National Academy Press, Washington, D.C., Figure 43-1, p.
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From page 240... ...
Fuel cells hold promise for zonal power generation. They are a particularly efficient and clean method of utilizing hydrocarbon fuels and are appropriate for medium-sized power generation units (1 to 4 kW)
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From page 241... ...
A . B: Mechanical Energy Storage Electrical Storage AC/DC Power Supply Inverter Charging System Switch To Load B: Mechanical Energy Storage with Pulsed Output | ChargingH Energy System| Storage Switch Energy System 24 To Load Switch To Load To Load FIGURE 8.3 Alternative techniques to provide multi-megawatt prime pulse power and power conditioning.
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From page 242... ...
Superconducting magnet energy storage (SMES) systems make it possible to store electrical energy directly with little loss other than the power required to cool the superconductor.
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From page 243... ...
These technologies will likely be introduced in cogeneration schemes such as topping cycles for gas turbines or direct heat sources such as nuclear reactors or thermoelectric nuclear devices. Superconducting Magnet Energy Storage and Generation Superconducting magnet energy storage (SMES)
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From page 244... ...
This technology takes the electrical feed from one of the prime power sources listed above into a conditioning stage, where the voltage level is altered for optimum, reliable power distribution to a slow powerconditioning stage. The major components of this first stage of power conditioning are inverters, transformers, and rectifiers.
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From page 245... ...
Technology Forecasts Capacitors As naval force requirements for compact electrical power systems grow substantially over the next 30 years, the development of capacitor technology will be a major enabling technology element. For microsecond to fractionalsecond energy storage and discharge, capacitor technology is unequaled in the flexibility and adaptability needed to meet a broad range of future requirements.6 At present, energy conditioning at pulse repetition rates of less than 1 Hz and 10 to 30 MJ per pulse has been achieved for pulse durations from 0.05 to more than 1,000 Us.
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From page 246... ...
SOI~CE: Adapted from the Board on Army Science and Technology, 1993, "Electric Power Technology for Battle Zones," STAR 21: Strategic Technologies for the Army of the Twenty-First Century, National Academy Press, Washington, D.C., Figure 43-4, p.
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From page 247... ...
SOURCE: Adapted from the Board on Army Science and Technology, 1993, "Electric Power Technology for Battle Zones," STAR 21: Strategic Technologies for the Army of the Twenty-First Century, National Academy Press, Washington, D.C., Table 43-9, p.
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From page 248... ...
In point-failure situations, bus conditioning via bidirectional inverters would continue to supply power from generator-to-generator feed lines redundantly, isolating damaged generator members of the system and permitting load sharing under inverter control. Because no other powerconditioning technology can provide this control, inverter do bus power conditioning is vital to the electrically powered naval forces of the future, and the Department of the Navy must ensure the development of this technology.
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From page 249... ...
Energy Storage and Recovery By the year 2035, there will be a greater dependence on electric power for vehicle drives as well as for a wide array of battlefield electronics and for new electrically driven weapon systems. The reduction of the signature of power generation units will become increasingly important in the battle zone of the future, and this will likely increase the dependence of the naval forces on compact energy storage systems, either chemical or mechanical, in which the stored energy can be rapidly recovered as electric output.
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From page 250... ...
Five classes of energy storage and electric-power recovery technologies that could apply to the forces' future needs were considered by the panel, as follows: Batteries, Flywheels, Inductive energy storage, Capacitive energy storage, and · Compressed gas or steam. The panel concluded that of these five storage technology areas, batteries show the greatest promise for meeting near-term needs, although flywheels may provide some capability in hybrid vehicle propulsion systems.
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From page 251... ...
1, Naval Surface Weapons Center, Silver Spring, Md., July. TABLE 8.5 Primary Cell Types with Promise as Prospective Power Sources Chemistry Cell Volt W-h/kg Notes Aluminum-Silver Dioxide 1.57 Pumped electrolyte; heat exchanger Al-Ag2O2 required Calcium-Thionyl Chloride 3.0 Increased tolerance to abuse over Li Ca-SOC12 Calcium-Sulfuryl Chloride 3.2 Increased tolerance to abuse over Li Ca-SO2C12 SOURCE: Compilation of data from Bis, R.F., J.A.
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From page 252... ...
Davis, and R.M. Murphy, 1986, Safety Characteristics of Lithium Primary and Secondary Battery Systems, NSWC TR 86-296, Naval Surface Weapons Center, Silver Spring, Md., July; and Bis, R.F., and R.M.
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From page 253... ...
1, Naval Surface Weapons Center, Silver Spring, Md., July. As the ships and aircraft of the future incorporate more electronics, they will require lightweight, reliable primary power sources and backup systems.
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From page 254... ...
Murphy, 1986, Safety Characteristics of Lithium Primary and Secondary Battery Systems, NSWC TR 86-296, Naval Surface Weapons Center, Silver Spring, Md., July; and Bis, R.F., and R.M. Murphy, 1986, Safety Characteristics of Non-lithium Battery Systems, NSWC TR 86-302 Rev.
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From page 255... ...
Davis, and R.M. Murphy, 1986, Safety Characteristics of Lithium Primary and Secondary Battery Systems, NSWC TR 86-296, Naval Surface Weapons Center, Silver Spring, Md., July; and Bis, R.F., and R.M.
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From page 256... ...
Sealed NiCds are slowly being developed for these applications and are in limited flight use in the commercial sector, but they have yet to demonstrate the high power densities and low maintenance levels of the mainline systems. And, only slightly further in the future, NiMH developments show great promise for increased power densities and lower cost.
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From page 257... ...
A factor of two to three improvement over lead-acid batteries is predicted for power density. To be applicable to the needs of the naval forces, devices in research today must evolve into rugged, fully reliable batteries.
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From page 258... ...
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From page 259... ...
Although the number, capability, and support requirements for smaller, more portable designs will enable a new range of remote sensor possibilities, these new sensors will also require the enhanced computational capabilities of microelectronic processors and validated, robust control programs. Networked Sensors A clear enabler of networked cooperative sensors is the development of reliable, very low power command and control and data exfiltration mechanisms.
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From page 260... ...
SMES as described above was developed for use in highpower, directed-energy weapons applications but has evolved into applications for long-term energy storage for uninterruptable power sources. The key technologies for SMES development in the future are superconducting materials and high-strength composite materials for containment of the large forces associated with magnetic energy storage.
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From page 261... ...
Within the IPS program, a family of modules is being defined that will serve as the building blocks for designing, procuring, and supporting marine power systems applicable across a broad range of ship types. To this end, shipboard power systems are divided into the following seven elements or module types: Power generation, Energy storage, Power conversion, Power distribution, Propulsion motors, Platform loads, and Power control.
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From page 262... ...
to 60 or 400 Hz, or variable frequency and voltage as required. The IPS architecture will allow incorporation of developing technologies such as PM electric machines, fuel cells, and PEBB into future ship designs as programmed, preplanned replacements for the core technology in the first-generation IPS modules.
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From page 263... ...
Navy Surface Ships," draft, Naval Sea Systems Command, Arlington, Va., Figure A-1, April 8, and (2) Krolick, C.F., 1996, "Technology Insertion," in the briefing "Advanced Surface Machinery Programs (ASMP)
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From page 264... ...
For some of these engines, the improved fuel efficiency comes at the expense of response time. Current ship service generator set voltage and frequency specifications require transient-response characteristics that these advanced turbine generator sets may not be able to meet without the addition of solid-state power conversion equipment on the output side.
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From page 265... ...
Fuel Cells Fuel cells convert chemical energy directly into electrical energy and as a power generation module can be viewed as a continuously fueled battery. They take in fuel and oxidant and produce electricity, water, and heat.
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From page 267... ...
is envisioned as the ship service power architecture for future surface combatants. It employs the dual port/starboard bus configuration used in the ac ZEDS introduced on the DDG-51 in FY 1994, but with do buses replacing the ac buses, and integrated power conversion centers (IPCCs)
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From page 268... ...
Power electronic devices, like microelectronic devices, are semiconductor devices that switch electrical currents on and off. Microelectronic devices switch very small currents at low power levels to control the flow of information.
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From page 269... ...
When available, the higher-voltage devices would be considered for propulsion power converters and for medium-voltage solid-state switchgear. Pulse-power Distribution This distribution provides for the generation, conversion, and transmission of prime power for high-energy pulsed loads such as electrothermal chemical (ETC)
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From page 270... ...
For IPS, the PTO, generator, and rectifier would probably be submodules within a PGM. If for some reason the main engines are not available, a stand-alone pulse prime power PGM could be developed that would include the engine, gearbox, generator, and rectifier and would add a flywheel off the PTO gear for energy storage.
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From page 271... ...
For Navy applications, there is the additional consideration of hydroacoustic performance for this effort the requirement was to be at least as good as today's surface combatants (e.g., DDG-51~. The steerable podded propulsor provides the greatest potential for meeting Navy hydrodynamic and hydroacoustic requirements while also being competitive with conventional propulsors on commercial ships.
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From page 272... ...
should be considered. It is anticipated that motor developments under the IPS program will support pod-mounted configurations; therefore, the modular propulsor effort will concentrate on the rest of the equipment needed to produce the steerable pod module.
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From page 273... ...
Navy dual-use and open-architecture standards for communications and computer resources. Future Impact on the Navy The Advanced Surface Machinery Program employs a systems engineering approach that maintains flexibility and minimizes investment until technologies are demonstrated, evaluated, and brought together for optimum total-ship costeffectiveness.
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From page 274... ...
advantage: Operators can determine how best to use the power, and the system saves 15 to 19 percent fuel in gas turbine surface combatants. SOURCE: Adapted from Krolick, C.F., 1996, "Advanced Surface Machinery Programs (ASMP)
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From page 275... ...
Advanced Surface Machinery Programs Office, 1996, "A Strategy Paper on Power for U.S. Navy Surface Ships," draft, Naval Sea Systems Command, Arlington, Va., Figure A-1, April 8, and (2)
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From page 276... ...
In any case, IPS diesel-based PGMs are likely to be identified to support the commercial end of the applications spectrum. Advanced cycle gas turbines in the 1- to 4-MOO range with fuel efficiency appreciably better than the existing DDA-501 are not commercially available at this time, although some commercial and DOE funding is going into their development.
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From page 277... ...
Also, if commercial or other government-funded efforts will not provide a full-scale stack with the characteristics required by naval force applications in time for demonstration with the fuel processor, then the Department of the Navy should consider investing in accelerating development of the stack. As fuel cell technology matures, it may achieve power density and costs that make it competitive as a larger-powerrated PGM as early as the 2010 time frame.
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From page 278... ...
Very low harmonic motor controllers; · High-power-density, high-performance, solid-state inverters and converters and the components thereof; Motors and generators with very low acoustic and magnetic signature, including versions that can operate submerged in seawater at high pressure; · New technologies for motors and generators such as superconducting magnets, cryogenic coolers, current collectors, high-field permanent magnets, liquid cooling, and active noise control; and · Electrical substitutes for systems and components that now rely on fluid transport for energy and actuation, including electric actuators, electromagnetic launchers, and thermoelectric coolers.
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From page 279... ...
Pulsed-power systems including energy storage pulse-forming networks and very high power solid-state switching; · Flywheel energy storage; · High-power density engines; . Electrical steering, suspension, and actuators; and · High power density electric drives at the unit size of several hundred horsepower.
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From page 280... ...
. Means for rapidly detecting and controlling the state of complex power distribution systems; · Electric motor and generator technologies that increase power and torque density, reduce acoustic and electromagnetic signature, operate at elevated temperatures, have higher efficiency, and/or allow operation submerged in seawater; · High-energy-density means for both long- and short-term electrical energy storage;
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From page 281... ...
ELECTRIC POWER AND PROPULSION 281 · Means for high-efficiency direct conversion of fuel to electric power; · Higher-speed, more efficient engines that increase power density while reducing fuel consumption; and · Higher-efficiency devices at the user end of the power system where the impact of efficiency is greatest (e.g., counterrotating propulsory.
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