Thursday, August 13, 2009


The Navy is testing new concepts in power generation, conversion, and distribution to make ships more efficient, economic, and combat-effective.


next-generation surface combatants, such as the DDG 1000 Zumwalt-class of guided missile destroy- ers will feature all-electric propulsion and an entirely new way of distributing power for propulsion, ship service, and combat capability. All-Electric Propulsion is a promising technology for both naval and commercial marine applications. An integrated power system (IPS) is an all-electric architecture, providing electric power to the total ship with an integrated plant. IPS enables a ship’s electrical loads, such as pumps and lighting, to be powered from the same electrical source as the propulsion system (e.g., electric drive), eliminating the need for separate power generation capabilities for these loads. To meet the increased power demands for new sea-based weapon systems,On the DDG 1000, power will be generated by two large gas turbine generators and two smaller ones. By using efficient power management, power is available to handle all of the electric loads throughout the ship, including potential future power-hungry weapons such as rail guns or directed energy weapons. The combat value of an electric ship goes well beyond weapon capability and capacity. There are significant efficiencies and redundancies. At full power, DDG 1000 will achieve speeds up to 30 knots. If one of the main turbines is lost, the plant can be isolated and still achieve 27 knots.
Among the major advantages of electric drive for naval ships is that the prime movers, whether gas turbines or diesels, do not need to be located in a central machinery space or mechanically connected to the propeller shaft as with traditional propulsion systems. For example, the engines can be placed in the bow, stern, or even in the superstructure for smaller engines. One of the advantages of distributed power in a warship is survivability. If an engine incurs damage or is incapacitated in one part of the ship, that part of the distribution system can be isolated while power can still be generated and distributed throughout the rest of the system.
Since a warship usually cruises at reduced power once it has arrived on station, normal station-keeping can be accommodated with the two small turbines to save fuel and reduce radiated noise. The power previ- ously trapped in the propulsion train can now be directed to enhance combat capability and mission flexibility. At lower speeds, Zumwalt has a surplus of power that can be made available as needed. Further advantages include the elimination of maintenance-intensive and high- temperature auxiliary steam systems, reduced noise and vibration, and better fuel efficiency.


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