Electric-Drive Propulsion for U.S. Navy Ships: Background and Issues for Congress

Publication Date: July 2000

Publisher: Library of Congress. Congressional Research Service

Author(s):

Research Area: Military and defense

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Abstract:

The Navy in January 2000 selected electric-drive propulsion technology for use on its planned next-generation DD-21 land-attack destroyer and is considering it for use on other kinds of Navy ships as well. Electric drive poses issues for Congress concerning its costs, benefits and risks, and how the technology should be integrated into the DD-21 program or other ship-acquisition programs.

Several foreign countries are developing or using electric drive in commercial or naval ships. The U.S. Navy's electric-drive development effort centers on the Integrated Power System (IPS) program. Several private-sector firms in the United States are now pursuing electric drive for the U.S. Navy market.

Electric drive offers significant anticipated benefits for U.S. Navy ships in terms of reducing ship life-cycle cost, increasing ship stealthiness, payload, survivability, and power available for non-propulsion uses, and taking advantage of a strong electrical power technological and industrial base. Potential disadvantages include higher nearterm costs, increased technical risk, increased system complexity, and less efficiency in full-power operations. The current scarcity of precise and systematic estimates of the costs and benefits of electric drive makes it difficult for policymakers to assess the relative cost-effectiveness of differing technical approaches to achieving electric drive. Some of the risks involved in developing electric-drive technology have been mitigated by the successful development of electric-drive technology for commercial ships; estimates of the amount of remaining risk vary.

The Navy has stated that developing common electric-drive components is feasible for several kinds of Navy ships and that pursuing electric drive technology in the form of a common family of components could have advantages for the Navy. The potential savings associated with a common system are difficult to estimate, but could be substantial. The concept of developing a common system or family of components poses issues for policymakers concerning the extent of commonality across electric-drive-equipped Navy ships and the use of competition in the development and procurement of electric-drive technology.

Much of the debate over electric drive concerns electric motors. The five basic types in question - synchronous motors, induction motors, permanent magnet motors, superconducting synchronous motors, and superconducting homopolar motors - differ in terms of their technological maturity, power-density, and potential applicability to different Navy ship types.

The Navy's decision to use electric drive on the DD-21 raises several potential issues concerning the acquisition strategy for the ship. Electric drive could be installed on Virginia (SSN-774) class submarines procured in FY2010, according to the Navy. Other candidates for electric drive include the Navy's planned TADC(X) auxiliary dry cargo ships, the Navy's planned joint command and control (JCC[X]) ships, the second through fifth LHA replacement ships, future aircraft carriers, and possibly the new cutters to be procured under the Coast Guard Deepwater project.