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

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

Order Code RL30622
CRS Report for Congress
Received through the CRS Web
Electric-Drive Propulsion for U.S. Navy Ships:
Background and Issues for Congress
July 31, 2000
(name redacted)
Specialist in National Defense
Foreign Affairs, Defense, and Trade Division
Congressional Research Service ˜ The Library of Congress

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

Contents
Introduction and Key Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Congressional Request . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Sources of Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Key Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Electric Drive in General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Application of Electric Drive to Specific Ship-Acquisition Programs . 9
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Basic Description of Electric Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Electric vs. Mechanical Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Integrated Electric Drive (Integrated Power System) . . . . . . . . . . . . 12
Key Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Common Electric Drive System . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
All-Electric Ship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Motor Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Anticipated Benefits and Potential Disadvantages . . . . . . . . . . . . . . . . . . . 16
Anticipated Benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Potential Disadvantages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Brief History of Electric Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Current Status of Electric Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Outside the United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
In the United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Associated U.S. Navy Ship Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Navy Report to Congress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Congressional Reaction to Navy Report . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Issues for Congress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Electric Drive in General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Electric Drive as a Technology Area . . . . . . . . . . . . . . . . . . . . . . . . . 38
Near-Term Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Measuring and Assessing Cost Effectiveness . . . . . . . . . . . . . . . . . . 39
Technical Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Common System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Other (Non-Motor) Components . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Application of Electric Drive to Specific Ship-Acquisition Programs . . . . 54
DD-21 Land-Attack Destroyers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Virginia (SSN-774) Class Submarines . . . . . . . . . . . . . . . . . . . . . . . 58
TADC(X) Auxiliary Dry Cargo Ships . . . . . . . . . . . . . . . . . . . . . . . . 59
Jcc(x) Joint Command and Control Ships . . . . . . . . . . . . . . . . . . . . . 60
LHA Replacement Ships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
CVN(X) Aircraft Carrier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Coast Guard Deepwater Cutters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Electric Drive Propulsion for U.S. Navy Ships:
Background and Issues for Congress
Introduction and Key Findings
Introduction
This report provides background information and discusses issues for Congress
regarding the use of electric-drive propulsion technology (as opposed to traditional
mechanical-drive technology) on U.S. Navy ships. As a result of technological
developments over the last few years, electric-drive technology has matured to the
point where the Navy has selected it 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 technology would change the way that U.S. Navy ships transmit
power from their engines to their propellers, as well as the way that they manage and
distribute electrical power to both propulsion and non-propulsion systems. (Electric
drive would not require the ship’s engines to be changed; ships could continue to be
powered by diesel engines, gas turbines, or steam turbines.) The Navy’s decision to
use electric-drive propulsion technology represents a technological shift for the Navy
arguably comparable in significance to the Navy's shift from sail to steam power in the
latter 1800s or the Navy's development of nuclear propulsion in the 1950s.
Electric-drive technology is being pursued by several foreign navies, most
notably in Europe, and is being incorporated into numerous commercial ships,
especially cruise ships. Electric-drive propulsion, particularly when installed as part
of a ship-wide integrated electrical power system, could generate substantial capability
and life-cycle cost benefits for U.S. Navy ships. Electric-drive technology, however,
still requires development work, and integrating it into nearer-term U.S. Navy ship-
acquisition programs, particularly the DD-21 program, involves a degree of technical
risk.
The debate over whether, when, and how to incorporate electric-drive
technology into Navy ship-acquisition programs has developed rapidly over the last
three years. Key developments over this period include the following:

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! In 1997, the Naval Studies Board of the National Research Council included
a substantial discussion of electric-drive technology in a major 9-volume report
on key technologies for the Navy and Marine Corps for the period 2000-2035.1
! In 1998, U.S. firms involved in developing electric-drive technologies began
to intensify their efforts and publicize them to both policymakers and the two
shipyard-led industry teams that are competing for the right to design the DD-
21 destroyer. These teams began to more intensively explore the potential for
equipping the DD-21 with electric drive.
! In June 1998, the Senate Appropriations Committee directed the Secretary of
the Navy to provide a report to the committee on the idea of a common
electric-drive system for the DD-21 and later ships in the Virginia (SSN-774)
class attack submarine program.
! In March 1999, the Navy delivered the report to Congress. The report 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.
! In May 1999, the Navy completed and began testing its full-scale, land-based
electric-drive demonstration system in Philadelphia.
! In January 2000, the Navy announced that the DD-21 class would be equipped
with electric drive and that proposed funding for development of electric-drive
technology was being increased by about $250 million over the period
FY2001-FY2005.2
Electric-drive propulsion poses a number of issues for Congress concerning its
potential costs, benefits and risks, and how the technology should be integrated into
the DD-21 program or other ship-acquisition programs. Although Congress has
approved funding for Navy research and development work on electric-drive in prior
years, the Navy’s plan to expand the scope of its electric-drive development effort and
apply electric drive to at least one new class of Navy ships may require Congress in
coming years to make significant decisions relating to the technology. The decisions
1 National Research Council. Naval Studies Board. Technology for the United States
Navy and Marine Corps, 2000-2035, Becoming a 21st-Century Force. Washington, National
Academy Press, 1997. Volume 2 (Technology), p. 16, 233-281, and Volume 6 (Platforms),
p. 19-22, 105-107.
2 For coverage of the Navy’s January 2000 announcement, see Walsh, Edward J. A
Fundamental Change of Direction. Sea Power, March 2000: 24-25; Brown, David. Electric
Plant to Power DD-21 Destroyer. Navy Times, January 17, 2000: 10; Seigle, Greg. USN
Decision on Electric Drive Means More Delays. Jane’s Defence Weekly, January 12, 2000:
3; Castelli, Christopher J. Navy To Make DD-21 First Electric Drive Surface Combatant.
Inside the Navy, January 10, 2000: 2; Suro, Roberto. Navy Plans High-Powered New
Destroyer. Washington Post, January 7, 2000: A3; Department of Defense News Release
007-00, January 6, 2000, entitled Integrated Power Systems, Electric Drive Selected for New
Navy Destroyers.

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that Congress reaches could have a profound affect on future Navy capabilities, Navy
research and development funding requirements, and the U.S. marine propulsion
technological and industrial base.
Congressional Request. This report is the result of a January 31, 1999 request
to CRS from Senator Trent Lott for analysis and conclusions concerning electric
drive. Senator Lott requested that the study examine the application of electric drive
to civilian cruise ships, commercial cargo ships, surface combatants, submarines and
aircraft carriers. The request stated that the report not be limited to U.S.
developments.3
Sources of Information. In response to Senator Lott's request, CRS in March
1999 circulated a 5-page list of questions on electric drive to Navy offices, the
Defense Advanced Research Projects Agency (DARPA), the National Academy of
Sciences, U.S. shipbuilding firms, firms involved in the development of electric-drive
technology, and other organizations. Recipients were invited to respond in writing
to any or all of the questions, as appropriate, to supplement their written responses
with in-person briefings if they so desired, and to distribute the list of questions to
other potentially interested parties.
Written responses, some quite extensive, were received in March and April 1999
from the U.S. Navy, the United Kingdom’s Royal Navy, numerous industry sources,
and additional respondents. Respondents included most of the parties to whom the
list of questions was originally sent by CRS, plus additional parties that received the
list of questions indirectly. Several respondents supplemented their written responses
with in-person briefings, some quite extensive. After reviewing these materials, CRS
posed some specific follow-on questions to some of the respondents to help clarify
or elaborate certain points; these inquiries resulted in some additional written
responses and telephone conversations.
These written responses, in-person briefings, and telephone conversations
constitute the primary sources of information for this report. These sources were
supplemented with additional file materials that CRS has collected on the topic since
the late 1980s, when CRS began to track developments relating to electric-drive
propulsion for Navy ships.
Key Findings
The key findings of the report are presented below. They can be divided into
two groups: findings relating to electric-drive technology in general, and findings
relating to the potential application of electric drive to specific U.S. ship-acquisition
programs.
3 Letter from Senator Trent Lott to Congressional Research Service, January 31, 1999.

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Electric Drive in General.4
Current Status of Electric Drive. Several foreign countries, particularly in
Europe, have developed, are developing, or are using electric-drive technology in
commercial ships, naval ships, or both. Much of the development work is
government-financed. The British Navy’s electric-drive program is particularly
significant. The electric-drive systems used today in cruise ships and other
commercial ships are generally made overseas, primarily in Europe. The three
primary European-based electric-drive suppliers are Alstom (previously known as
Cegelec), Asea Brown Bovieri (ABB), and Siemens.
Electric-drive technology is used on a few U.S. government ships and is being
developed in the United States by both the U.S. Navy and private industry. The
Navy’s effort centers on the Integrated Power System (IPS) program, which was
established in 1995. As mentioned above, the IPS program recently completed
construction of a full-scale, land-based electric-drive demonstration system. Testing
of this system, located in Philadelphia, began in May 1999. The Navy’s prime
contractor for this system is Lockheed Martin, but much of the actual equipment was
provided by Alstom. Several other firms are also involved. The Navy is proposing
a total of more than $300 million for research and development on electric drive
during the period FY2001-FY2005.
Several private-sector firms in the United States are now pursuing electric-drive
technology for the U.S. Navy market. At least three private-sector entities are
offering complete electric-drive systems to the Navy:
! Alstom, which has marine operations in Britain, France, Germany, and the
United States (in Pittsburgh and Philadelphia). The company supplies electric-
drive systems featuring synchronous motors and is also developing systems
featuring induction and permanent magnet motors.
! an industry team led by General Dynamics Corporation, a leading designer
and builder of U.S. Navy ships. This team is developing an electric-drive
system featuring a permanent magnet motor.5
! an industry team led by Newport News Shipbuilding (NNS), another leading
designer and builder of U.S. Navy ships. This team is also developing an
electric-drive system featuring a permanent magnet motor.
In addition to these three entities, other U.S. firms are also involved in
developing electric-drive technologies or components. These include, among others:
4 A basic description of electric-drive (as opposed to mechanical-drive) technology can
be found in the background section of this report.
5 As discussed in the background section of the report, five kinds of electric motors are
discussed in connection with electric-drive technology for ships – synchronous motors,
induction motors, permanent magnet motors, superconducting synchronous motors, and
superconducting homopolar motors.

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! American Superconductor, which is developing a superconducting
synchronous motor, and
! General Atomics, which is developing a superconducting homopolar motor
that was previously under development for many years by the U.S. Navy.
Anticipated Benefits and Disadvantages. Electric-drive technology 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. Electric drive has potential disadvantages in terms of higher near-term
costs, increased program risk, increased system complexity, and less efficiency in full-
power operations.
Electric Drive as a Technology Area. Although electric drive is often
discussed as a specific system that could be available in the near future for the DD-21
program, many elements of electric-drive technology have the potential to evolve and
improve over time. This suggests that policymakers might consider addressing
electric drive as not simply a proposal for a specific system that might require a few
nearer-term acquisition decisions, but as a broader technology area that might require
longer-term management and oversight and a series of research, development, and
procurement decisions stretching over the course of several years. If conducting
longer-term management and oversight of electric drive is considered appropriate, it
might be assisted by developing an electric-drive technology development roadmap
or master plan extending perhaps 10 to 25 years into the future.
Near-Term Costs. Pursuing electric-drive will incur higher near-term costs than
a strategy that places continued emphasis on mechanical-drive technology.
Developing electric-drive technology for warships would require hundreds of millions
of dollars in research and development funding in coming years, particularly if the
technology is developed for submarines as well as surface ships, and if development
of more advanced electric-drive technologies is pursued. Several (but not all) sources
for this report stated that electric-drive systems initially would be more expensive to
procure than mechanical-drive systems. The cost premium for a commercial electric-
drive system (which might be suitable for use in Navy auxiliary ships) could be less.
These sources, however, agreed that the procurement cost of electric-drive systems
would come down over time, and that the higher initial costs of electric-drive systems
would be more than offset over the longer run by reduced ship life-cycle operating
and support costs.
Measuring and Assessing Cost Effectiveness. Several sources agreed that the
cost-effectiveness of electric drive should be examined not by focusing on the electric-
drive system or any of its components in isolation, but rather by examining the effect
that electric drive has on overall ship cost and capability. In an expanded version of
this perspective, the cost-effectiveness of electric drive might also be measured in
terms of its effect on total fleet costs and capabilities. Estimates of the costs and
benefits of electric-drive technology should arguably include measures that examine
not just shorter- but also longer-term (i.e., life-cycle or total ownership) costs and
warfighting effects.

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Although electric-drive technology offers numerous potential cost and
warfighting benefits for Navy ships, relatively few precise estimates are available on
the magnitude of these benefits. If not redressed, the scarcity of precise and
systematic estimates will make it difficult for policymakers to assess with any
precision the potential cost-effectiveness of electric-drive technology in general and
(probably more significant) the relative cost-effectiveness of differing technical
approaches to achieving electric drive.
The Navy’s interest in electric-drive technology is consistent with the decisions
of commercial ship operators (especially cruise ship operators) and other navies in
recent years to move to electric-drive technology for their own ships. The strong
interest in electric drive by other navies (particularly the British Navy) suggests that
electric drive offers a variety of warfighting and life-cycle cost advantages for naval
ships. The interest shown by other navies in electric drive, however, also
demonstrates that there are multiple technical approaches to electric drive that should
be assessed.
Technical Risk. Incorporating electric-drive technology into Navy ship-
acquisition programs could add technical or schedule risk to those programs. The
potential amount of risk varies, depending on the exact configuration of the system
in question. More advanced approaches to electric drive present greater potential
technical or schedule risk, but also promise greater potential cost effectiveness.
Electric-drive components presenting potential technical or schedule risk include
motor drives, motors, generators, the electrical distribution system, advanced
propeller/stern configurations, and overall system design and integration. Issues to
be addressed include demonstrating at full scale technologies that to date have been
demonstrated at partial scale, improving thermal performance, achieving desired levels
of acoustic quieting and shock resistance, and designing overall system interfaces,
controls, and module specifications.
Some of the risks involved in developing electric-drive technology have been
mitigated by the successful development of electric-drive technology for commercial
ships. Some industry sources argue that the amount of remaining risk involved in
developing electric drive for Navy use is low to moderate. Other sources suggest that
the degree of risk may be higher, particularly if the technology is developed on an
aggressive schedule. Technical risk involved in developing electric drive might be
mitigated through more intensified research and development.
Common System. The Navy stated in its March 1999 report to Congress 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 Navy and the other military
services have used commonality in numerous acquisition programs over the years, and
Navy leaders are now placing increased emphasis on the concept.
Potential advantages of a common electric-drive system (or a family of common
components) include nearer-term cost savings due to streamlining of research and
development costs, both nearer- and longer-term savings due to greater efficiencies
in procurement, and longer-term savings due to the streamlining of fleet training,

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operation, and support efforts. Potential savings 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. Past acquisition experience clearly suggests that
designing a unique electric-drive system for each kind of ship would not result in the
most cost-effective application of electric drive across the fleet. Past experience,
however, does not prove conclusively that it would be achieved by an approach that
would install a common system or family of components on every kind of ship that is
scheduled to be powered by electric drive. Commonality is not an end in itself but
rather would be a strategy for policymakers to consider in seeking the most cost-
effective path to apply electric-drive technology across the fleet. Policymakers might
wish to assess the relative merits of both a maximally common approach and more
mixed approaches that combine elements of commonality with elements of ship-
specific solutions.
Pursuing a common electric-drive system or family of components could in
theory lead to the emergence of a dominant or monopoly supplier to the Navy of
electric-drive technology, components, and systems. In light of this possibility,
policymakers who place a high value on the use of competition in defense
development and procurement might consider taking actions aimed at ensuring that
any Navy acquisition strategy for electric drive makes maximum use of competition
between competing industry approaches prior to selecting the approach that would
form the basis for the common system. From this perspective, it may also be
appropriate to aim at ensuring that nearer-term acquisition decisions preserve, as
much as possible, a potential for employing competition in the eventual development
and procurement of follow-on electric-drive technologies, components, and systems.
One possible approach would be to require the common electric-drive system to be
designed to a so-called open architecture. Another possible approach would be to
provide continuing funding to firms other than those who supply the current electric-
drive system to finance continued development of potential competing technologies
or components.
Motors. Much of the debate since 1998 over the application of electric-drive
technology to U.S. Navy ships concerns the type of electric motor that should be
used. The issue is highly charged because specific motor types are associated with
specific firms competing for a part of the Navy’s prospective electric-drive program.
The electric motors associated with electric-drive systems for large ships can be
divided into five basic categories – synchronous motors, induction motors, permanent
magnet motors, superconducting synchronous motors, and superconducting
homopolar motors.
The synchronous motor can be considered the most mature technologically in
application to large ships. There is a consensus among both naval and industry
sources that the synchronous motor, if scaled up to the higher horsepower ratings
needed to move surface combatants and submarines at high speeds (i.e., 30+ knots),
would be too large and heavy to be suitable for use on these ships. The most likely
apparent opportunity for incorporating electric-drive systems using synchronous

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motors (presumably commercially available systems) into the Navy’s electric-drive
effort would be to install them in large Navy auxiliary ships.
The induction motor is generally considered the second-most mature motor type
for application to large ships, after the synchronous motor. It is the type of motor
used in the Navy’s full-scale, land-based electric-drive demonstration system. Most
of the sources consulted for this report argue (or do not contest) that it can be
sufficiently power-dense to be suitable for use on U.S. Navy surface combatants. By
the same token, however, most sources – including the U.S. Navy in its March 1999
report to Congress – also argue (or do not contest) that the induction motor is not
sufficiently compact or quiet to be suitable for use on U.S. Navy submarines. Using
an electric-drive system with an induction motor (rather than the currently less mature
permanent magnet motor) might help mitigate the risk of integrating electric-drive
technology into the DD-21 program, but would preclude achieving motor
commonality across surface ships and submarines.
The permanent magnet motor can be made quieter and significantly more power-
dense than the induction motor – enough so that it is consequently considered suitable
for use on submarines as well as surface combatants. Sources generally agree that the
permanent magnet motor can be used in a common electric drive system for Navy
surface ships and submarines. The Navy’s March 1999 report to Congress focuses
on the permanent magnet motor as the motor available in the nearer term that would
be suitable for a common electric-drive system.
The permanent magnet motor is less mature technologically than the induction
motor, and consequently at this point may pose more development risk to incorporate
into a nearer-term ship-acquisition program such as the DD-21 destroyer. Sources
differ regarding the amount of technical risk involved in scaling up the permanent
magnet motor to full size. Some argue that the basic technological issues in
permanent magnet motors have been resolved, and that scaling up the technology will
not pose any new issues; others demur, arguing that scaling up is never risk-free. The
Navy’s decision, announced in February 2000, to delay the procurement of the first
DD-21 by one year (to FY2005) will, other things held equal, reduce the risk
associated with equipping the first DD-21 with an electric-drive system using a
permanent magnet motor.
The superconducting synchronous motor, if successfully developed, could be
more power-dense and quieter than a permanent magnet motor. The superconducting
synchronous motor is less mature technologically than the permanent magnet motor
and was not discussed in the Navy’s March 1999 report. Most sources argue (or do
not contest) that it cannot be matured quickly enough to be installed at acceptable risk
on the first DD-21. Advocates of the superconducting synchronous motor, while not
necessarily disagreeing, argue that the technology for this kind of motor has
progressed in recent years and that the time needed to mature the technology may be
less than others estimate. The firm developing this motor says that, with adequate
funding, it could be developed and completed by 2009, making it possible to have the
motor enter service with the fleet in 2012.

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The superconducting homopolar motor,6 if successfully developed, could
similarly be more power-dense and quieter than a permanent magnet motor. The Navy
worked on developing the homopolar motor for many years starting in the mid-1970s.
The homopolar motor, like the superconducting synchronous motor, is less mature
technologically than the permanent magnet motor and was given little emphasis in the
Navy’s March 1999 report. Advocates of this motor, like those of the
superconducting synchronous motor, argue that the technology for this kind of motor
has progressed in recent years and that the time needed to mature the technology may
be less than others estimate. The firm now developing this type of motor says that,
with adequate funding, it could be developed and completed in 5 or 6 years.
Other (Non-Motor) Components. There is considerable potential for evolution
and improvement in the non-motor elements of electric-drive technology. This is
potentially significant, because with the partial exception of the motor drive, there has
been relatively little discussion of how these other components could or should evolve
or be improved.
Application of Electric Drive to Specific Ship-Acquisition Programs.
DD-21 Land-Attack Destroyers. Given the possibility that the DD-21's system
might become the basis for a common electric-drive system for the Navy, the
economic stakes for firms competing to build the system are potentially very high.
The Navy’s acquisition strategy for the DD-21 program gives the two industry teams
that are competing for the right to design the DD-21 wide latitude in selecting the
type of electric-drive system the ship would use. This approach is consistent with
Navy and Department of Defense acquisition reform efforts.
The potential for the DD-21's electric-drive system to become the basis of a
common electric-drive system, together with the Navy’s acquisition strategy for the
program, raise several potential issues for Congress. These issues concern: the DD-
21 program schedule and its effect on the technical risk in developing electric drive;
the adequacy of DD-21 program funding for development of electric drive; the
achievability of the DD-21 ship procurement cost goal; the potential for evolving the
DD-21's electric drive system over time; the appropriateness of the latitude given to
the two DD-21 industry teams in determining the ship’s propulsion system; and how
to reconcile the potentially conflicting goals of optimizing electric drive for DD-21
and optimizing it for application to multiple Navy ship types.
Given the competing motor technologies now being pursued, there are numerous
potential strategies that can be pursued concerning the type of motor used in the DD-
21 electric-drive system. Sources differed regarding the amount of technical risk
associated with incorporating different versions of an electric-drive system into the
first DD-21. The lowest-risk option would appear to be a system using an induction
motor connected by a traditional horizontal shaft at the stern of the ship to a fixed-
6 The term homopolar (i.e., unipolar) refers to the fact that this motor uses direct current
(rather than alternating current) electricity and does not require either a reversal of current or
electrical commutation. As a result, the magnetic field and the electrical current in the
armature of a homopolar motor are constant over time and space (i.e., unvarying).

CRS-10
pitch propeller. With some added risk, the lead ship’s system could include a
permanent magnet motor rather than an induction motor. Eventually, an advanced
propeller/stern configuration such as a podded propeller7 could be developed for the
DD-21.
On June 14, 2000, Ingalls Shipbuilding, the leader of one of the two industry
teams competing for the DD-21, announced that it had selected the NNS-led electric
drive industry team for the preliminary design of an electric drive propulsion system
and will incorporate the NNS-led team’s permanent magnet motor design into its
initial system design proposal for the DD-21.
Virginia (SSN-774) Class Submarines. Electric-drive technology in some form
could be installed on follow-on Virginia-class submarines. Navy officials testified in
June 2000 that a nearer-term electric-drive system could be ready for a Virginia-class
boat procured in FY2010. Some industry sources suggested that it could be ready for
a boat procured in FY2007 if a decision were made in the near term to pursue the
option and adequate development funding was provided.
Some industry sources have suggested, and the Navy did not disagree, that
electric-drive technology for submarines, if pursued ambitiously, has the potential for
altering the stern of a Virginia-class submarine in a way that could reduce the
procurement cost of the submarine (currently $1.9 billion to $2.0 billion) by as much
as $100 million. Pursuing electric-drive technology for submarines this ambitiously,
however, would be very expensive: It could easily require hundreds of millions of
dollars, or even more than a billion dollars, in research and development funding
beyond the funding that the Navy has already programmed for development of
electric-drive technology.
TADC(X) Auxiliary Dry Cargo Ships. The Navy’s planned TADC(X) class of
auxiliary dry cargo ships, the first of which was procured in FY2000, is a near-term
candidate for electric-drive propulsion. As a large, slower-speed, non-combat ship
now in procurement that is somewhat similar to a commercial cargo ship, it might be
feasible and cost-effective to equip the TADC(X) with a currently available European
commercial electric-drive system similar to those now being used for cruise ships.
JCC(X) Joint Command and Control Ships. Electric drive might similarly be
a candidate for the joint command and control (JCC[X]) ships that the Navy plans to
begin procuring in FY2004. If these ships are built to commercial-ship standards, the
JCC(X) might be a candidate for a commercial electric-drive system. The operational
requirements of the JCC(X), however, might require a Navy-developed electric-drive
system with better quieting and shock resistance.
LHA Replacement Ships. LHD-8 – a modified Wasp (LHD-1) class ship that
will be the first LHA replacement ship – is to be equipped with a hybrid propulsion
plant consisting of a low-power electric-drive system for low-speed operations and
a mechanical-drive system for higher-speed operations. The Navy is now assessing
7 See figure 3 in the background section (page 18) for an illustration of a podded
propeller.

CRS-11
whether the second through fifth LHA replacement ships should be additional (and
further-modified) LHD-1 class ships or a new-design amphibious assault ship known
as the LHX. The further-modified-LHD option might, and the LHX option more
certainly could, include a full electric-drive system.
CVN(X) Aircraft Carrier. The Navy’s March 1999 report to Congress on
electric drive states that while electric drive is feasible for future aircraft carriers,
mechanical drive would be more appropriate for CVN(X)-1, the first of the Navy’s
planned class of next-generation aircraft carriers, which is to be procured in FY2006.
The Navy’s conclusion contrasts with a 1997 Naval Research Advisory Committee
(NRAC) report on the CVN(X) that strongly endorsed equipping the CVN(X) with
electric-drive technology. Policymakers may review the Navy’s 1999 conclusion
periodically (e.g., with the procurement of each carrier) to determine whether it
remains valid.
Coast Guard Deepwater Cutters. The 1998 Navy-Coast Guard national fleet
concept, with its emphasis on commonality, raises the possibility of using electric-
drive on the new cutters that are to be procured under the Coast Guard Deepwater
project. Equipping these cutters with electric-drive could produce ship capability and
life-cycle cost benefits for the Coast Guard similar to those that electric-drive
technology is expected to produce for the Navy, and potentially improve economies
of scale for both the Navy and Coast Guard in the production, operation, and life-
cycle support of ship propulsion systems. Incorporating electric drive into the
Deepwater program, however, would pose several significant issues in terms of
feasability, cost, and program disruption, particularly since the first cutter is to be
procured in 2002 and competing Deepwater industry teams have already completed
much of their design work for the ship.
Background
Basic Description of Electric Drive
Electric vs. Mechanical Drive. A ship's drive system is the equipment that
transmits power from the ship's engines to its propellers. It is roughly analogous to
the transmission and drive shaft in a car, which transmit power from the car's engine
to its wheels.
Most of the world's larger civilian and military ships today use a mechanical-
drive system. In very simplified form, with a mechanical-drive system, the higher-
speed revolutions per minute (RPMs) produced by a ship's engine (also known as the
prime mover) are transmitted by a rigid shaft to a set of gears, known as reduction
gears, that convert (i.e., reduce) these higher-speed RPMs to the lower-speed RPMs
that are more appropriate for a larger ship's propeller. A second rigid shaft then
transmits these lower-speed RPMs from the reduction gears to the propeller. Ships
with multiple propellers have multiple engines, reduction gears, and sets of shafts.
With an electric-drive system, in contrast, a generator converts the engine's
higher-speed RPMs into electricity. This electricity is then transmitted by an electrical

CRS-12
cable toward the stern of the ship, to a device called a motor drive or motor
controller, which modifies the voltage and frequency of the electricity as needed for
the ship's electric motor to operate properly and at the desired speed. The electric
motor then converts the electricity into lower-speed RPMs that turn the propeller.
Ships with multiple propellers have multiple electric motors and motor drives.
Figure 1 depicts the basic arrangements of mechanical- and electric-drive
systems.
Integrated Electric Drive (Integrated Power System). Ships with mechanical-
drive systems actually have two sets of engines. One set is used for ship propulsion,
as described above. A second and separate set, connected to electrical generators, is
used to generate electricity for all of the electrically powered equipment on the ship.
A U.S. Navy Arleigh Burke (DDG-51) class destroyer, for example, has a set of four
large gas-powered turbine engines for propulsion, and a second set of three smaller
gas turbines that produce electrical power for the ship.
In a ship with a mechanical-drive system, the power-producing capability of the
ship's propulsion engines typically represents 75 percent to 85 percent of the ship's
total power-producing capability. This power-producing capability is devoted
exclusively to ship propulsion and is not available for non-propulsion uses, even when
the ship is stationary or traveling at low speed.
Ships with an electric-drive system, in contrast, can be designed so that a single
set of engines produces a common pool of electricity that is used for both ship
propulsion and the ship's non-propulsion electrical loads. Such a system is known as
an integrated electric-drive (IED) system or integrated power system (IPS).
In ships with integrated electric drive, the electricity produced by the engines and
generators is sent by cable to an electric switchboard that divides the electricity into
two flows -- one for the ship's propulsion needs, and one for the ship's other electrical
loads. The switchboard can alter the distribution of power between these two uses
on a moment-to-moment basis, as needed, to meet the ship's propulsion and non-
propulsion needs.
With an integrated electric drive, the large amount of power needed to propel
the ship at high speeds is thus available, if needed, for other uses. Even when the ship
is traveling at high speed, power can be momentarily diverted away from the
propulsion system to a non-propulsion system that needs a short burst of high-
strength power without appreciably slowing the ship down. An integrated electric
drive is roughly analogous to the arrangement in the "Star Trek" science fiction
television series, in which the captain of the star ship can order the ship's engineer to
divert power from the ship's engines to its weapons or other systems.
All current proposals for using electric drive propulsion on U.S. Navy ships
envisage an integrated electric drive system. Consequently, in this report, the term
electric drive is used to refer to integrated electric drive. Figure 1 shows the basic
arrangement of an integrated electric drive system.

CRS-13
Figure 1.
Engine
Reduction
gears
Shaft
Shaft
Propeller
Basic mechanical-drive system
(not to scale)
Engine
Generator
Motor
Motor
drive
Cable
Cable
Shaft
Propeller
Short shaft
Basic electric-drive system
(not to scale)

CRS-14
Key Components. As shown in Figure 2, an integrated electric drive system
includes the following major elements:
! Engines (also known as prime movers). On U.S. Navy surface combatants,
the engines are gas turbines (modified versions of jet engines used on
commercial airliners) that burn jet fuel. On U.S. Navy submarines and most
U.S. Navy aircraft carriers, the engines are steam turbines whose steam is
created using heat produced by a nuclear reactor. On other ships (particularly
those with lower maximum speeds), the prime movers can be diesel engines.
! Generators, which convert the mechanical energy produced by the engines –
higher-speed RPMs – into electricity.
! Electric switchboard, which distributes the electricity to propulsion and non-
propulsion needs.
! Motor drives (also known as motor controllers), which modify the voltage
and frequency of the electricity as needed for the ship's electric propulsion
motors to operate properly and at the desired speed.
! Motors, which convert electrical power from the motor drives to lower-speed
RPMs suitable for a large ship's propellers.
! Propellers, which use the lower-speed RPMs to propel the ship through the
water.
! Non-propulsion power distribution system, which distributes the remaining
electrical power to the various non-propulsion electrical loads around the ship.
This system includes additional cables, switches and power-conversion devices.
Common Electric Drive System. Over the last year or two, the terms
"common electric drive" and "common integrated electric drive" have come into use
to refer to an electric drive system that is designed with common components that can
be installed on various types of Navy ships (e.g., submarines, surface combatants,
amphibious ships, and auxiliary ships).
All-Electric Ship. On some ships today, some auxiliary systems are either
steam-powered (e.g., space heaters, laundry equipment, and galley [kitchen]
equipment), hydraulically (fluid) powered (e.g., steering systems and submarine diving
systems), or pneumatically (air) powered (e.g., valve actuators and surface-ship
turbine engine starters). On an integrated electric drive ship, converting these
remaining non-electrical systems to electrical power would produce what is known
as an all-electric ship. Some observers view the all-electric ship as a natural
progression from an integrated electric drive ship.

CRS-15
Figure 2.
Engine
G enerator
Sw itchboard
M otor
M otor
Cable
drive
Cable
Cable
Shaft
P ropeller
S hort s haft
E lectrical power
for non-pro pulsion
electrical loads
Basic integrate d electric-drive syste m
(not to scale )

CRS-16
Motor Types. A key element in discussions of electric drive concerns the type
of motor to be used. The motor types associated with electric-drive systems for large
ships can be organized into the five general categories shown in the table below. They
all convert electrical energy into mechanical energy (RPMs). They differ, however,
in certain key characteristics, including the type of electrical current used – alternating
current (AC) or direct current (DC) – the source of the magnetic field that is
combined with the flow of electrical energy to create mechanical energy; and whether
the motors conduct the electrical energy using use conventional electrical wires or
superconducting wires and associated technology.
Table 1. Basic Motor Types for Large-Ship Electric-Drive Systems
Long Name
Short Name
AC wound-field synchronous motor
Synchronous motor
AC induction (asynchronous) motor
Induction motor
AC permanent magnet synchronous motor
Permanent magnet motor
AC superconducting synchronous motor
Superconducting synchronous motor
DC superconducting homopolar motor
Homopolar motor
In addition, it should be noted that three versions of the permanent magnet
motor have been discussed in connection with electric-drive systems for ships – the
radial-gap (radial-flux) version, the axial-gap (axial- flux) version, and the transverse-
flux version. These versions differ in the design and orientation of their fixed and
rotating elements (their stators and rotors) and consequently in how electromagnetic
lines of flux in the motors work to create mechanical movement. In short, a radial-
gap motor can be described as a cylinder rotating within another cylinder; the axial-
gap motor can be described as a disk spinning between two other disks, and the
transverse-flux motor can be described as a rimmed disk whose rim spins inside
slotted rings.
Anticipated Benefits and Potential Disadvantages
Anticipated Benefits.8 Electric-drive technology 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.
Reduced Ship Life-Cycle Cost. Depending on the kind of ship in question and
its operating profile (the amount of time that the ship spends traveling at various
speeds), a Navy ship with an integrated electric-drive system may consume 10 percent
8 For examples of articles discussing the benefits of electric drive, see McCoy, Timothy
J. Powering the 21st Century Fleet. U.S. Naval Institute Proceedings, May 2000: 54-58;
Leonard, Robert E, and Thomas B. Dade. The All Electric Ship: Enabling Revolutionary
Changes in Naval Warfare. Submarine Review, October 1998: 43-53.

CRS-17
to 25 percent less fuel than a similar ship with a mechanical-drive system. The Navy
estimates a savings of 15 to 19 percent for a ship like a surface combatant.
In addition, electric drive makes possible the use of new propeller/stern
configurations, such as a podded propulsor (see Figure 3), that can reduce ship fuel
consumption further due to their improved hydrodynamic efficiency. Estimates of
additional savings range from 4 percent to 15 percent, depending on the ship type and
the exact propeller/stern configuration used.9
For fossil-fueled ships, fuel consumption is a major contributor to annual ship
operating and support costs. Over the life of the ship, the savings from reduced fuel
consumption promise to significantly outweigh the potential increase in initial
procurement cost associated with electric drive, thus significantly reducing the ship's
total life-cycle cost, also known as total ownership cost (TOC). The Navy is now
placing increased emphasis on life-cycle cost in the acquisition process so as to more
effectively capture the long-term cost consequences of its acquisition decisions.
In addition to savings on fuel, it is anticipated that electric-drive systems may
require less maintenance and fewer crew members to operate than mechanical-drive
systems. Electric-drive systems can be designed to be highly automated and self-
monitoring. Reductions in maintenance and crew size would further reduce ship life-
cycle cost.
Increased Stealth. Electric drive promises to be significantly quieter acoustically
than mechanical drive. Since acoustic noise is an important component of a ship's
overall detectability, ships equipped with electric drive promise to be less detectible
(i.e., more stealthy) than ships equipped with mechanical-drive technology.
9 A podded propulsor is a streamlined, roughly cylindrical pod with a propeller attached
to one end (usually the front end) that is suspended from the bottom of the ship. The pod,
which contains the electric motor driving the propeller, can be designed to swivel in a circle
so as to direct the propeller’s thrust in any direction and thereby steer the ship. A podded
propulsor eliminates the need at the stern of the ship for a lengthy, exposed horizontal shaft
leading to the propeller and a rudder for steering the ship. With a podded propulsor, there are
fewer exposed components to create drag (i.e., resistance to forward movement), and the
propeller encounters a more uniform (i.e., less disturbed) water flow, increasing its efficiency
(i.e., its ability to use its RPMs to create thrust). Using podded propulsors can improve a
ship’s maneuverability by permitting a tighter turning radius and by giving it the ability to
change the ship’s direction of movement or its orientation even at very low speeds. A podded
propulsor might also offer certain advantages in terms of maintenance and repair, since the
pod can be detached and quickly repaired or replaced by a like unit without need for cutting
an opening into the ship’s hull and working around other equipment. For an article discussing
podded propulsion systems, see Bonner, Kit. Naval Propulsion for the 21st Century: The
Azipod System. U.S. Naval Institute Proceedings, August 1999: 74-76.

CRS-18
Figure 3.
Conventional propeller/stern arrangement with horizontal shaft,strut, propeller, and rudder
(not to scale)
Motor
Potential revised propeller/stern arrangement with rotating podded propulsor and no rudder
(not to scale)

CRS-19
The significantly improved quieting promised by electric drive may be the single
most important benefit of electric drive to the Navy's submarine community.
Stealthiness is fundamental to a submarine's survivability and effectiveness and
acoustic noise remains the most reliable method by which submarines can be detected
and tracked at longer ranges. The Navy has expended significant resources over the
last few decades on making its submarines increasingly quiet (so as to stay ahead of
increasingly capable adversary submarine-detection equipment), and has stated that
electric drive is needed to provide the next significant improvement in acoustic
quieting on submarines.10
Although traditionally not as critical for surface warships, stealthiness –
including acoustic quieting – is becoming increasingly important as a contributor to
surface warship survivability and effectiveness. The improved acoustic quieting
promised by electric drive thus promises to be of benefit to surface ships as well. In
addition, electric-drive, by permitting a reduction in the volume devoted to air intakes
and exhaust ducts, can reduce a surface ship’s infrared signature and radar cross
section. New propeller/stern configurations made possible by electric drive might
reduce the wake signature of surface ships, which could reduce their detectability by
remote overhead sensors and improve their chances of defeating much-feared wake-
homing torpedoes.
Increased Payload. In a surface combatant, electric drive's reduced fuel
consumption can translate into a reduction in the amount of space aboard ship
required for fuel storage.11 In addition, by eliminating the so-called "tyranny of the
shaft line" -- the need, in a mechanical drive system, to install the engines, reduction
gears, shafts, and propellers in a long line running along the bottom of the ship --
electric drive makes it possible to install the various parts of a surface combatant's
drive system in positions that may use space aboard ship in a more efficient manner.
For example, it may permit the ship's turbine engines to be located higher in the ship,
reducing the amount of interior space required for the ducts that are needed to take
air down into the engines and to carry exhaust gases away from the engine.
In both these ways, electric drive may free up space aboard the ship that can be
used to carry additional payload (e.g., weapons or sensors). Freed-up space can also
be used for other purposes, such as increasing the size of staterooms for members of
the ship’s crew so as to improve their quality of life aboard ship – an objective which
has recently emerged as a Navy priority.
Increased Survivability. Electric-drive can improve ship survivability in several
ways. Eliminating mechanical drive's tyranny of the shaft line can improve ship
survivability by eliminating the possibility that one or more of the ship's long shaft
lines will be thrown out of alignment and rendered useless by a nearby weapon
explosion. Eliminating the requirement to locate elements of the ship's drive system
10 Bender, Bryan. US Navy Sets Sights on Electric Attack Submarine. Jane’s Defence
Weekly, July 26, 2000; Bowman, Frank L. “Skip.” Submarines in the New World Order.
Undersea Warfare, Spring 1999: 7.
11 Alternatively, if fuel storage capacity is held constant, electric drive can permit an
increase in ship operating endurance (range).

CRS-20
all in a straight line along the bottom of the ship makes it possible to place them in
locations where they may be better protected from attack by certain weapons (e.g.,
mines).
Electric drive makes it possible to more widely distribute elements of the
propulsion system around the ship, making it less likely that a single weapon might
disable the entire drive system. With an integrated power system, the flow of power
from distributed power sources can be rapidly reconfigured in the event of damage
to the ship to ensure a continued supply of electricity to vital systems. Past
experience with battle damage to naval ships suggests that this could be a very
significant benefit. And for surface ships, electric drive permits smaller propulsion
machinery spaces, which could facilitate damage control and permit greater use of
automated damage-control technologies.
Increased Power Available for Non-Propulsion Systems. As mentioned earlier,
electric drive makes large amounts of power available for non-propulsion uses such
as powerful radars and sonars, laser weapons, high-power microwave weapons,
electromagnetic rail guns, electrothermal guns, electromagnetic aircraft launch and
recovery systems (i.e., electromagnetic catapults and arresting wires), or rapidly
charging the batteries of unmanned air vehicles (UAVs), unmanned underwater
vehicles (UUVs), and high-energy undersea sensor networks.12 Some of these
functions, particularly the weapons, may require peak power levels measured in tens
of megawatts, and adding this much electrical-generating capacity to a mechanical-
drive ship would incur substantial additional costs.13
Strong Technological and Industrial Base. Some elements of the Navy's
current mechanical-drive systems, particularly reduction gears that have been specially
engineered for quiet operations, are generally not found in commercial application,
limiting economies of scale in their production and support. Advocates of electric
drive argue that as commercial ships shift to greater reliance on electric drive,
mechanical-drive technology will experience declining economies of scale that will not
only increase its production and support costs, but also possibly reduce the incentive
for manufacturers of mechanical-drive components to invest in further improvement
of mechanical-drive technology. In contrast, advocates of electric drive argue,
electric-drive propulsion will benefit from increasing production and support
economies of scale, and will also be able to take advantage of rapid technological
advances in the large and vibrant commercial electrical-power and electronics
industries.
Potential Disadvantages. Electric drive has potential disadvantages in terms
of higher near-term costs, increased program risk, increased system complexity, and
less efficiency in full-power operations.
12 See, for example, Bender, Bryan. US Navy Sets Sights on Electric Attack Submarine.
Jane’s Defence Weekly, July 26, 2000.
13 Electric drive in the future could also facilitate the replacement of today’s prime
movers (e.g., diesel engines, gas turbine engines, or steam turbines) and generators with more
efficient power-producing technologies, including direct energy-conversion devices such as
fuel cells.

CRS-21
Higher near-Term Costs. Pursuing electric-drive technology would incur higher
near-term development costs than a strategy that places continued emphasis on
mechanical-drive technology. Most sources also stated that electric-drive systems
would initially be more expensive to procure than mechanical-drive systems.
Increased Program Risk. Sources for this report acknowledged that
incorporating electric-drive (rather than mechanical-drive) technology into Navy ship-
acquisition programs could add technical or schedule risk to those programs, since
electric-drive technology is less mature than mechanical-drive technology for
application to naval ships. Areas of potential technical risk in developing electric-
drive technology, depending on the approach taken, include motor drives, motors,
generators, the electrical distribution system, advanced propeller/stern configurations,
and overall system design and integration.
Increased System Complexity. Electric drive can add complexity to the ship’s
design both in the number of major elements involved in the drive train14 and in the
complexity of the ship’s electrical system. Added complexity in general can raise
potential concerns regarding issues such as overall system reliability and
maintainability. Proponents of electric drive argue that the technology has shown
itself to be highly reliable and maintainable after extensive use in cruise ships and other
commercial ships.
Less Efficiency at Full Power. Electric-drive systems can be less efficient than
mechanical-drive systems for full-power (i.e., maximum-speed) operations, due to the
energy losses involved in converting RPMs into electricity, and electricity back into
RPMs.15 Naval ships, however, typically spend only a small fraction of their time at
full power. Typically, most of their time – about 80 percent, by one estimate – is
spent at half-speed (roughly one-eighth power) or less. As a result, for naval ships,
losses due to the somewhat lower efficiency when operating at full power will likely
be more than offset by gains due to higher efficiency when operating at partial power.
Brief History of Electric Drive

Electric-drive technology dates to about 1910, following the development of the
first large electric motors and generators. At that time, electric-drive systems
(developed by the United States) and mechanical-drive systems employing reduction
gears (developed by the British) were both being perfected and competed against one
another. By the 1920s, the British developed a lightweight, high-efficiency
mechanical-drive system, and mechanical drive emerged as the predominant ship
propulsion technology. As summarized by one naval writer,
The history of electric propulsion in naval vessels began in 1912 with the US
Navy’s fleet collier Jupiter [AC-3], successfully powered by a Melville-McAlpine
turbo-electric system and prototype for future capital ship installations. In 1919,
14 Some sources disagreed with this, saying that when auxiliary systems are taken into
account, electric-drive systems can be made less complex than mechanical-drive systems.
15 This is why electric drive is viewed as not necessarily better than mechanical drive for
commercial cargo ships that sprint between ports at consistently high speeds.

CRS-22
the US Congress, still refusing funds for aircraft carrier construction as such,
made an allocation for the conversion of the Jupiter to the Navy’s first, albeit
experimental, aircraft carrier Langley (CV-1), which entered service in 1922.
Three 32,000 [shaft horsepower] New Mexico class turbine powered
[mechanical drive] battleships were ordered in 1914 but, in build [during
construction], it was decided to install a turbo-electric [i.e., electric-drive] system
in the lead ship.... While this was a heavier [drive system] installation than those
of the two sister ships, the New Mexico proved more economical, flexible, and
provided better manoeuverability. Nevertheless, during major refits over 1931-
1933, all three ships were given new 40,000 shp [shaft horsepower] straight
turbine [mechanical drive] installation[s] for an extra 0.75 kts [knots].
In 1915, two Tennessee class [battleships], similar to the New Mexico...
were ordered. These were immediately followed by three almost identical
[Colorado-class ships], also with turbo-electric propulsion. The foregoing five
battleships were survivors of the 1922 Washington Naval Treaty under which 11
further projected electric-driven capital ships were cancelled....
Two further products of the treaty were the Lexington (CV-2) and Saratoga
(CV-3), survivors of a class of six battle cruisers ordered over 1916-1919 and on
which work was stopped on the slip. Work on the named ships restarted in 1922
to complete them as aircraft carriers, the U.S. Navy’s first real two [ships] of the
type.... During WWII, the US produced numbers of turbo-electric vessels due, to
some extent, to a shortage of [reduction] gear-cutting capacity in those years.16
16 Wood, Geoffrey. Electric Propulsion In Warships – Then and Now. Naval Forces,
No. 3, 1995: 20. Another naval analyst has written that:
a major U.S. Navy success story of the early part of [the 20th] century [was] turbo-
electric drive for capital ships (five battleships and the battle cruisers completed
as the carriers Lexington (CV-2) and Saratoga (CV-3)).... Turbo-electric power
was abandoned only because the post-World War I naval arms treaties made it
vital to save weight; geared turbines [used in mechanical-drive systems] were far
lighter. The U.S. Navy was unique in adopting turbo-electric power for major
warships (some [cruise] liners built after World War I also were turbo electric),
probably because the pre-1914 United States had the world’s most advanced
electric power industry.
The U.S. Navy revived turbo-electric plants during World War II for destroyer
escorts, because U.S. gear-cutting capacity was insufficient. As in capital ships,
turbo-electric machinery carried a considerable cost in weight and volume. As it
turned out, however, the necessary lengthening of the ships’ hulls reduced
hydrodynamic (wave-waking) resistance enough to balance off the extra weight,
and the resulting Buckley (DE-51)- and Rudderrow (DE-224)-class escorts were
as fast as the geared turbine design would have been (which was not, in the event,
built as planned). These ships apparently proved entirely satisfactory. (Friedman,
Norman. Navy Commits to Electric Drive. U.S. Naval Institute Proceedings,
April 2000: 4, 6.)
See also Eisman, Dale. Advantage of Electric Ships Hasn’t Changed Much Since 1900's.
(continued...)

CRS-23
After World War II, mechanical-drive technology continued to be improved and
remained the dominant approach. Among warships, electric-drive technology was
widely adopted only for submarines, where the diesel-electric power plant became the
standard system because it permitted the submarine to propel itself submerged for
limited periods of time on battery power, without need for access to the atmosphere
as a source of oxygen for use in burning a fossil fuel.17
In the years after World War II, electric-drive technology was occasionally
reexamined for use on ships other than smaller diesel-electric submarines. The United
States, for example, built two one-of-a-kind nuclear-powered attack submarines to
experiment with the technology -- the Tullibee (SSN-597), which entered service in
1960 and was decommissioned in 1988, and the Glenard P. Lipscomb (SSN-685),
which entered service in 1974 and was decommissioned in 1990. Electric drive was
also used in some large commercial ships, such as the cruise ships Normandie (in
1936) and Canberra (in 1960).
These periodic experiments, however, tended to confirm that electric-drive
technology, while promising, was not competitive with modern mechanical-drive
technology for large submarines and surface ships. The Tullibee and Glenard P.
Lipscomb, for example, were significantly slower than other Navy attack submarines
due to limits on the power of their electric motors, and their drive systems were very
maintenance-intensive.18
The post-World War II dominance of mechanical drive began to be challenged
starting in the mid-1970s, when technological developments in motors and particularly
motor drives made electric drive potentially more cost-effective than mechanical drive
for larger naval ships.
With regard to motors, large warships require high-horsepower motors that are
reliable, power-dense (i.e., compact), shock-resistant, and quiet, and that deliver their
horsepower in the form of slow RPMs (suitable for slowly revolving ship propellers)
but high torque.19 High-horsepower electric motors have existed for many years, but
they tend to be high-RPM/low-torque machines rather than low-RPM/high-torque
machines. In the 1980s, moderate-horsepower, low-RPM/high-torque electric motors
were developed, but their horsepower was still not sufficient to move large warships
16(...continued)
Virginian-Pilot, February 11, 2000.
17 In a diesel-electric submarine, a diesel engine (using air drawn down from the surface
through a snorkel) is used to generate electricity that is stored in batteries. This stored
electrical power is then drawn from the batteries to power the ship during submerged
operations.
18 See, for example, Lipscomb Exit May Have Lessons For Burke Electric Drive. Navy
News & Undersea Technology, January 29, 1990: 2.
19 Torque is the twisting power of the motor on the shaft, measured in foot pounds of
force. An everyday analogue can be found in doorknobs: a stiff or heavy doorknob requires
the hand and arm to generate more torque to operate than does a light or loose doorknob. For
motors, horsepower is the product of RPMs times torque, divided by 5252.

CRS-24
at high speeds. Only in the last several years has development work progressed on
high-horsepower, low-RPM/high-torque electric motors that are sufficiently power-
dense and quiet for use on surface combatants and submarines.
With regard to motor drives, only within the last few years has it been possible
to develop devices that could handle the high amounts of electrical power associated
with high-horsepower motors and convert it efficiently into the kind of high-quality
(i.e., almost-distortion-free) power needed to ensure that an electric motor engineered
to operate quietly will in fact operate quietly.20 Developments in the last couple of
years in power electronics – semiconductor-based electronic devices that are capable
of handling large flows of power, as opposed to the much smaller flows of energy
handled by the semiconductor chips in a computer – have progressed to the point
where it is now possible to build high-capacity motor drives that can operate
efficiently and deliver very-high-quality power to high-horsepower electric motors.
The development of semiconductor-based power-conversion devices also made
integrated electric drive possible because these devices can efficiently convert large
amounts of electrical power into differing forms needed for propulsion and non-
propulsion uses. Electric-drive systems using AC motors21 control the speed of the
motor by varying the frequency of the electric power fed from the motor drive. This
made the electrical power unsuitable for other electrical systems on the ship, which
require electric power at a stable frequency. As a result, older AC electric drive
systems could be used only for ship propulsion and could not be integrated with other
systems aboard the ship to produce an integrated electric drive.
In 1985, the United Kingdom took advantage of these developments and began
building a new class of frigates, known as the Duke class or Type 23 ships, which
employ a combined diesel-electric and gas turbine-mechanical drive propulsion plant.
The ships use a lower-power diesel-electric drive system for quiet sonar-towing
operations at speeds of up to about 15 knots, and a gas turbine-mechanical drive
system for higher-speed operations up to the ships' maximum sustained speed of about
28 knots.22 The first Type 23 frigate entered service in 1990 and their drive systems
have been favorably received. The ships use much less fuel than comparably sized
mechanical-drive ships such as the U.S. Navy’s Oliver Hazard Perry (FFG-7) class
frigates, have demonstrated high reliability, and are very quiet compared to earlier
ships when operating at lower speeds.
In 1987, the cruise ship Queen Elizabeth II underwent an overhaul during which
its mechanical-drive system was replaced with an integrated electric-drive system.
20 Distortions in the electrical power that is delivered to the motor can lead to noise-
producing irregularities in the motor’s performance.
21 Some electric motors are designed to use AC current; others are designed to use DC
current. It was not practical to make conventional DC motors with ratings of more than about
10,000 or 15,000 horsepower. That was large enough to power small non-nuclear-powered
submarines (where DC motors are widely used), but not enough to power large surface ships
at higher speeds. Electric-drive-equipped surface ships thus tended to use AC motors.
22 For a discussion, see Preston, Christopher. Novel Electric Drive For the RN’s Type
23 ASW Frigates. Jane’s Defence Weekly, September 7, 1985: 473, 475, 477.

CRS-25
This system was also deemed successful in operation and set the stage for widespread
adoption of electric-drive technology in the cruise ship industry. Today, most if not
all cruise ships under construction in the world are being built with electric drive.
Electric drive is now used almost exclusively in icebreakers and floating offshore oil
platforms, and is becoming more common in passenger and car ferries. Other kinds
of commercial ships now being built with electric drive include shuttle tankers, pipe-
and cable-laying ships, and research ships.
Current Status of Electric Drive
Outside the United States. Several foreign countries, particularly in Europe,
have developed, are developing, or are using electric-drive technology in commercial
ships, naval ships, or both. Much of the development work is government-financed.
These countries include the United Kingdom, France, Germany, Italy, the
Netherlands, Finland, Sweden, Canada, Russia, Japan, South Korea, and China,
among others.
Commercial Ships. The electric-drive systems used today in cruise ships and
other commercial ships are generally made overseas, primarily in Europe. The three
primary European-based electric-drive suppliers are Alstom (previously known as
Cegelec)23 and Asea Brown Bovieri (ABB)24 – which together account for most of
the electric-drive systems in operation today – and Germany-based Siemens, which
has a smaller market share but is considered a leader in permanent magnet motors and
associated advanced motor drives.
Naval Ships. Developments regarding electric-drive technology in foreign
(mostly European) navies include the following:
In General. Virtually all of the world’s non-nuclear-powered submarines have
electric-drive systems. Until recently, all of these submarines were diesel-electric
boats that use diesel engines as the prime movers. A few countries, particularly in
Europe, are now introducing so-called air-independent propulsion (AIP) systems that
use fuel cells, Sterling engines, or closed-cycle diesel engines rather than conventional
diesel engines as the prime movers. In spite of the change in the prime mover,
however, these submarines are still electric-drive boats.25
23 As discussed later, Alstom is an international company headquartered in Paris that has
marine operations in Britain, France, Germany, and the United States (in Pittsburgh and
Philadelphia). The firm’s marine business is directed from Britain.
24 ABB’s primary electric-drive facilities are in Finland and Italy.
25 For examples of discussions of AIP systems on non-nuclear-powered submarines, see
Walsh, Don. The AIP Alternative. Sea Power, December 1999: 34-37; Scott, Richard.
Boosting the Staying Power of the Non-Nuclear Submarine. Jane’s International Defense
Review, No. 11, 1999: 41-44, 46, 48-50; Ritterhoff, Jurgen. Class 214 – A New Class of Air-
Independent Submarines. Naval Forces, No. 5, 1998: 94-98, 100; Windolph, Wolfgang. The
Better AIP. Naval Forces, No. 4, 1998: 114-116, 118-120; Scott, Richard. Power Surge.
Jane’s Defence Weekly, July 1, 1998: 24-27; de Lionis, Andres. The Allure of AIP Beckons
the Navies of Developing States. Jane’s Intelligence Review, February 1998: 39-41;
(continued...)

CRS-26
NATO. Electric-drive technology was endorsed as feasible and viable for future
frigate-sized surface combatants by an October 1998 report from a NATO technical
study group on future naval ship design.26 This study was undertaken by 50 technical
experts from more than 30 companies in 8 NATO countries (Canada, France,
Germany, Italy, the Netherlands, Spain, Turkey, and the United Kingdom).
United Kingdom. In addition to the Type 23 frigates discussed above, whose
electric-drive system was provided by Alstom (then Cegelec), the British Navy has
two auxiliaries that use electric drive – a seabed operations vessel and a former
commercial support ship that was converted into a forward repair ship. The United
Kingdom is also using commercial (modified cruise ship) electric-drive systems in two
new Albion-class amphibious ships and two new Wave-class auxiliary oilers, all now
under construction, and on two planned logistics landing ships.
The British Navy has approved and recently re-endorsed a 1996 Marine
Engineering Development Strategy that envisages using electric drive on future
warships and auxiliaries. The British Navy is now seriously considering using electric
drive on a variety of planned warship classes, including a medium-sized (by U.S.
standards) aircraft carrier, a nuclear-powered attack submarine, and two surface
combatants – the Type 45 destroyer and the Future Surface Combatant (FSC). The
baseline design for the FSC includes electric drive. Given the now-established use of
commercial electric-drive systems on recently ordered British amphibious and
auxiliary ships, it appears likely that future classes of such ships in the British Navy
will also use electric drive.
The British Ministry of Defence has funded development of advanced electric-
drive technologies for possible use on future ships under an Integrated Full Electric
Propulsion (IFEP) program established in 1996. These technologies include a
transverse-flux permanent magnet motor being developed by Alstom and Rolls Royce.
The British Navy plans to build a land-based IFEP technology demonstrator,27 and is
using electric drive on an experimental trimaran (three-hulled) research ship (the
Triton) that is intended to explore hull and mechanical options for future warships.
25(...continued)
Robertson, Thomas. Air Independent Propulsion. Naval Forces, No. 6, 1996: 36-39; Annati,
Massimo. AIP Systems: a Solution for Everybody? Military Technology, No. 11, 1996: 107-
108, 110-112; Donaldson, A. J. Submarine Power Sources For the Mission. Naval
Engineers Journal, May 1996: 129-146 (includes comments by others).
26 North Atlantic Treaty Organization. NATO All Electric Ship, NIAG SG/54 Pre-
Feasibility Study, Final Report. NATO, Brussels, 1998. (Document AC/141-D/737, NIAG
[NATO Industrial Advisory Group] - D(98) 9. For a published summary of this study, see
Weigel, Dieter. NATO Study on An All Electric Warship. Naval Forces, No. 5, 1999: 45-
49. The results of the NATO study are also briefly summarized in Pengelley, Rupert.
Turning The Naval Propulsion Helm. Jane’s Navy International, January/February 1999:
10-15.
27 For a discussion, see Scott, Richard. Rivals [sic] Teams Power Up For Electric Ship
Demonstrator. Jane’s Defense Weekly, December 22, 1999: 12.

CRS-27
(As discussed below, the U.S. Navy is also participating in the Triton experimentation
program.)28
France. France’s nuclear-powered submarines all use electric-drive technology.
One press report states that “the French Navy is understood to have decided in
principle to adopt integrated full electric propulsion for its future warships.”29
Jeumont Industrie in France is supplying an axial-gap permanent magnet motor for the
new Scorpene-class non-nuclear-powered submarine being built in France for Chile
and is currently developing a permanent magnet motor for use in the next French
nuclear-powered submarine. According to one source, Jeumont is developing a type
of electric motor not otherwise discussed in this report – a superconducting
permanent magnet motor.30
Germany. Germany is using electric-drive systems in minesweepers, an
oceanographic ship (whose system incorporates a permanent magnet motor), and non-
nuclear-powered submarines. The new Type 212 German non-nuclear-powered
attack submarine, scheduled to enter service in 2003, will use an advanced submarine
electric-drive system that includes fuel cells as an alternative to a diesel engine and a
permanent magnet motor, both made by Siemens. A second German company,
Magnet-Motor, is also involved in developing permanent magnet motors for use in
all military services. Work on permanent magnet motors by both firms began in the
1980s. The German firm MTG (Marine Technische Gesellschaft) Marinetechnik
reportedly has completed a design study for the German Ministry of Defense for a
3,000-ton SWATH (small waterplane area, twin-hull) electric-drive demonstration
ship featuring a radial-gap permanent magnet motor; the ship is being built by the
German shipbuilder Thyssen Nordseewerke and is expected to be completed in
2002.31
Italy. Italy is building its own German-designed Type 212 submarines; these
ships will also use Siemens-made fuel cells and permanent magnet motors. ABB in
Italy developed a prototype permanent magnet motor for the Italian submarine
program, but the Italian Navy selected the Siemens motor.
Netherlands. A significant recent example reflecting state-of-the-art electric-
drive technology in deployed form in a warship is the Dutch Navy’s new amphibious
ship Rotterdam, which entered service in 1998. This 12,750-ton ship has an electric-
28 For more on the British Navy’s electric-drive development efforts, see Pengelley,
Rupert. Future Electric, Harnessing the Promise of IFEP. Jane’s Navy International,
July/August 1997: 14-15, 17-18, 20-21; Hodge, CG, and D.J. Mattick. The Electric Ship,
an Update. Review of Naval Engineering, Vol. 51, No. 4: 11-18; and Pengelley, Rupert.
Turning The Naval Propulsion Helm. Jane’s Navy International, January/February 1999:
10-15. Electric-drive technology is also used on British-owned cruise ships.
29 Pengelley, Rupert. Europeans Go For Electric Drive. Jane’s Navy International,
January/February 1999: 3.
30 Electric drive is also being used in French cruise ships and chemical tankers.
31 Pengelley, Rupert. Europeans Go For Electric Drive. Jane’s Navy International,
January/February 1999: 3.

CRS-28
drive system provided by the firm Holec Ridderkerk featuring induction motors. The
ship has a maximum sustained speed of 19 knots.32 In addition, “in January 1998 the
Netherlands released its All Electric Ship (AES) strategy document, large parts of
which are characterised as having been taken verbatim from the UK antecedent.”33
Russia. Russia uses electric-drive technology in icebreakers. Given Russia’s
history as a significant naval power and as a developer of various naval technologies
(including both nuclear and gas-turbine propulsion), it is very possible that Russia may
be attempting to develop (within available resources) more advanced electric-drive
technologies.
In the United States. Electric-drive technology is used on a few U.S.
government ships and is being developed in the United States by both the U.S. Navy
and private industry.34
U.S. Government Ships. U.S. government ships equipped with electric drive
include the new U.S. Coast Guard icebreaker Healy, which was procured in FY1990-
FY1993 and entered service in 1999, three older icebreakers, several Military Sealift
Command (MSC)-operated TAGOS-type ocean surveillance ships procured between
FY1979 and FY 1990, a few TAGS-type ocean surveying ships that were procured
in FY1990-FY1996, and a few AGOR-type oceanographic research ships that are
operated by academic institutions under the Navy’s University National
Oceanographic Laboratory System (UNOLS).
U.S. Navy Study and Development Efforts. The Navy’s more recent electric-
drive technology study and development efforts began in 1979 with an assessment of
then-current technology in the area. Electric drive was selected by the Navy for use
in the DDGX, which became the Arleigh Burke (DDG-51) class destroyer. This
decision, however, was subsequently reversed due to concerns over cost and schedule
risk.
In 1984, the Navy explored designs for a potential new frigate (FFX) intended
to replace the Navy’s aging Knox (FF-1052) class frigates. The FFX program was
subsequently cancelled but informed later Navy efforts on electric drive.
A series of Navy studies in 1986-1989 on a potential destroyer-like ship called
the Battle Force Combatant included consideration of a variety of new propulsion
technologies, including electric drive. This work was carried forward under the
Integrated Warship Systems Demonstration Program (IWSDP), which was later
dropped.
32 Electric-drive systems are also used in Dutch ferries.
33 Pengelley, Rupert. Turning the Naval Propulsion Helm. Jane’s Navy International,
January/February 1999: 10-15.
34 For an overview of U.S. government and industry efforts on electric drive, see Walsh,
Edward J. Transforming Shipboard Power. Sea Power, October 1999: 50-52.

CRS-29
In September 1988, then-U.S. Chief of Naval Operations Admiral Carlisle Trost
endorsed the use of electric drive for the Navy's next surface combatant class.35 In
1989-1993, the Navy funded full-scale advanced development work on an electric-
drive system for a SWATH ship. In 1989, the Navy began development work on a
zonal electrical distribution system (ZEDS), which would form part of an integrated
electric-drive system. An AC version of such a system has been incorporated into
later (Flight IIA) ships in the DDG-51 program. The first Flight IIA DDG-51 was
procured in FY1994 and is scheduled to enter service in 2000. A DC version of
ZEDS is under development.
U.S. Navy IPS Program. In 1992, a Navy program on a 21st Century Destroyer,
using work done under the Navy’s Advanced Surface Machinery Program (ASMP),
concluded that incorporating an electric-drive system into the ship’s design could
actually reduce its procurement cost. To engineer this system and carry out risk-
reduction work, the Navy in 1995 established its Integrated Power System (IPS)
program.36
35 For information on this Navy interest in electric drive during this time, see, for
example, Russell, James A. Navy Eyes Electric Drive For New Ships. Navy News &
Undersea Technology, January 3, 1986: 1-2; Russell, James A. Electric-drive Ship Gets
Boost From Superconductors. Navy News & Undersea Technology, July 3, 1987: 4; Elliott,
Frank. Electric Drive Warships Will Revolutionize Ship Design. Navy News & Undersea
Technology, June 6, 1998: 4-5 (see also related article on pages 1 and 3); Rumsey, Anne.
Navy Ready To Award Work For Electric Drive. Defense Week, July 25, 1988; Black,
Norman. Electricity Proposed As Power Of The Future For Navy Warships. Hartford
Courant, September 30, 1988: 8; Trost Endorses Electric Drive, Promises Use In Future
Ships. Navy News & Undersea Technology, October 3, 1988: 1, 3; Halloran, Richard. U.S.
Plans Electric Power to Drive New Warships. New York Times, October 9, 1988: 37;
Matthews, William. After 75 Years, Navy Returns to Electricity to Power Its Ships. Defense
News, October 10, 1988: 6; Rumsey, Anne. Adm. Trost Puts Electric Drive Into High Gear.
Defense Week, November 28, 1988: 5; Friedman, Norman. Electric Drive Revisited. U.S.
Naval Institute Proceedings, December 1988: 149; Navy Begins Work on Propulsion System
of the Future. Navy News & Undersea Technology, February 13, 1989: 4-5; Walsh, Edward
J. Prime Movers. Sea Power, March 1989: 55-58; Rumsey, Anne. Navy Slows Drive For
Electric-Powered Ships. Defense Week, May 15, 1989: 7; Lane, Maury. Navy Designs
Radical Ship Propulsion System. Defense News, July 3, 1989: 1, 28; Superconductor
Technology Would Cost 25% Less Than Navy Electric Drive Plan. Inside the Navy, August
28, 1989: 7; Electric Transmission and Podded Propulsors For the US Navy of the 2000s.
Maritime Defence, November 1989: 355-356; Navy `Integrated Electric Drive' R&D
Accelerates. Sea Power, February 1990: 42-43; Navy Abandons Goal To Install Integrated
Electric Drive on DDG-51 Destroyer. Inside the Pentagon, November 15, 1990: 3-4; Navy
Officials Say Service Is Abandoning Electric Drive on DDG-512 Ship. Inside the Navy,
November 19, 1990: 1, 11-12; Lawson, Richard. Advanced Ship-Propulsion Program
Changes Name, Focuses on Affordability. Inside the Navy, November 18, 1991: 16;
Rosenberg, Eric. It’s Wait And See For Navy’s Electric Drive. Defense Week, January 21,
1992: 2.
36 For descriptions of the IPS program in its earlier stages, see IPS: The US Navy’s
Next-Generation Power/Propulsion System. Maritime Defence, December 1996: 278-279;
Doerry, Norbert, et al. Powering the Future with the Integrated Power System. Naval
Engineers Journal, May 1996: 267-282; Walsh, Edward J. Surface Fleet Looks To “All-
(continued...)

CRS-30
In 1995, the IPS program supported advanced development work on a partial-
scale axial-gap permanent magnet motor. This work was done by Newport News
Shipbuilding, Kaman Electromagnetics Corporation (KEC) and the Naval Surface
Warfare Center (NSWC) at Annapolis.
Since 1995, the IPS program has carried out full-scale advanced development
work on electric drive. The IPS program recently completed construction of a full-
scale, land-based demonstration electric-drive system. Testing of this system, located
at the Naval Sea Systems Command (NAVSEA) Advanced Propulsion and Power
Generation Test Site (APPGTS) in Philadelphia (on the site of the former Philadelphia
naval shipyard), began in May 1999 and is scheduled to continue through FY2001.
The Navy is using this land-based system as part of a demonstration and risk-
reduction effort for electric-drive technology in general and the DD-21 program in
particular. A second goal is to develop the site as a test facility for future electric-
drive technology developments. The Navy’s prime contractor for this system is
Lockheed Martin, but much of the actual equipment was provided by Alstom.
Several other firms are also involved.
The IPS program is also testing electric-drive technology with the British Navy
on the British technology demonstration ship Triton as part of a joint U.S.-U.K.
technology demonstration effort. Specifically, the U.S. Navy will use the Triton to
test elements of the IPS program’s ship-wide power distribution system. At-sea tests
with the Triton are scheduled to begin in 2001 and continue to 2003.37
In 1998, the IPS program was transferred to the DD-21 program office.
Although most of the Navy’s work on electric drive in recent years has been carried
out under the IPS program, additional work has been conducted outside the IPS
program. For example, development work outside of the IPS program on electric
drive for submarines was funded in FY1998. This work focused on developing
submarine-suitable electric-drive systems that employ permanent magnet motors.
Participants in this work include General Dynamics’ Electric Boat and Electro-
Dynamics divisions, Newport News Shipbuilding, KEC, Eaton, and Westinghouse
Electro-Mechanical Division.
U.S. Navy Funding for Electric Drive. The tables below show prior-year
(FY1989-FY2000) and programmed (FY2001-FY2005) Navy funding for electric
drive.38
36(...continued)
Electric Ships.” Sea Power, May 1996: 33-34.
37 U.S. Department of the Navy. TRIMARAN Integrated Power System (IPS) Project
Plan. Washington (?), 1998, 16 p. (December 1998)
38 These tables do not include funding for research and development electric-drive
technologies carried by the Office of Naval Research (ONR). Prior to FY1994, ONR funding
for electric drive amounted to less than $1 million per year. For FY1994 through FY2000,
ONR funding for electric drive was as follows: $4.3 million (FY1994), $2.1 million
(FY1995), $13.1 million (FY1996), $21.8 million (FY1997), $21.5 million (FY1998), $26.8
(continued...)

CRS-31
Table 2. Prior-Year Funding for Navy Electric Drive Research and
Development (FY1989-FY2000)
(millions of current dollars)
FY89
FY90
FY91
FY92
FY93
FY94
FY95
FY96
FY97
FY98
FY99
FY00
24.0
29.0
52.0
12.4
9.1
9.7
13.7
28.7
21.3
26.5
31.8
25.7
Table 3. Programed Funding for Navy Electric Drive Research and
Development (FY2000-FY2005)
(millions of current dollars)
FY00
FY01
FY02
FY03
FY04
FY05
25.7
84.1
106.3
69.3
26.9
10.0
Industry Development Efforts. Several private-sector firms in the United States
are now pursuing electric-drive technology for the U.S. Navy market. At least three
private-sector entities are offering complete electric-drive systems to the Navy:39
! Alstom (previously known as Cegelec), an international company
headquartered in Paris that has marine operations in Britain, France, Germany,
and the United States (in Pittsburgh and Philadelphia). The firm’s marine
business is directed from Britain. Alstom has been involved in marine electric-
drive technology since 1920 and today is a leading international supplier of
commercial and naval electric-drive systems. The company supplies electric-
drive systems featuring synchronous motors and is also developing systems
featuring induction and permanent magnet motors.40
38(...continued)
million (FY1999), and $47.9 million (FY2000). Source: Department of Defense information
paper on ONR initiatives supporting electric drive, provided to CRS by the Navy Office of
Legislative Affairs, July 17, 2000 (LA-581-379).
39 For discussions of industry efforts on electric drive, see Nagy, Barbara. Propelled By
Urgency. Hartford Courant, April 14, 2000: E1; Lerman, David. Power Play. Newport
News Daily Press, March 12, 2000: 1; Walsh, Edward J. A Fundamental Change of
Direction. Sea Power, March 2000: 24-25; Schweizer, Roman. Newport News-Kaman
Unveil Electric Drive System to Challenge GD Team. Inside the Navy, August 16, 1999: 5-6;
Muradian, Vago. NNS-Kaman Unveil Modular Electric Propulsion for DD-21. Defense
Daily, August 13, 1999: 6-8; Holzer, Robert. Newport News Pushes Electric Drive Funding
Scheme. Defense News, May 31, 1999: 6; Holzer, Robert. General Dynamics Pushes for
Electric Drive. Defense News, April 19, 1999: 4, 26.
40 Alstom has supplied electric-drive components or systems for scores of commercial
ships and several naval ships, including the British Navy’s Type 23 frigates, which entered
service starting in 1990, its two new Albion-class amphibious ships, which are scheduled to
enter service in 2002-2003, and its two new Wave-class auxiliary oilers, which are scheduled
to enter service in 2000-2001. In addition to being a principal supplier of the U.S. Navy’s
(continued...)

CRS-32
! an industry team led by General Dynamics Corporation, a leading designer
and builder of U.S. Navy ships.41 The team includes, among other firms, GD’s
Electric Boat and Bath Iron Works shipyards, two other GD divisions,
Westinghouse Electro-Mechanical Division (WEMD), Eaton Controls, and
Northrop Grumman Marine Systems. This team is developing an electric-drive
system featuring a permanent magnet motor.
! an industry team led by Newport News Shipbuilding (NNS), another leading
designer and builder of U.S. Navy ships.42 The NNS-led team also includes,
among other firms, Kaman Electromagnetics Corporation (KEC), which
develops and builds electric motors and related systems. This team is also
developing an electric-drive system featuring a permanent magnet motor.43
In addition to these three entities, other U.S. firms are also involved in
developing electric-drive technologies or components. These include, among others:
! American Superconductor of Westborough, MA, which is developing, in
conjunction with Rockwell Corporation, a superconducting synchronous
motor (and also superconducting wire and related technologies that could be
incorporated into various electrical systems), and
! General Atomics of San Diego, CA, which is developing a superconducting
homopolar motor that was previously under development for many years by
the U.S. Navy.
Associated U.S. Navy Ship Programs
40(...continued)
land-based electric-drive prototype system in Philadelphia, Alstom supplied the electric-drive
systems for the U.S. Coast Guard’s new icebreaker, the Healy, and the Navy’s new ocean
surveillance ship Impeccable (TAGOS-23), which was procured in FY1990 and entered
service in 1999. For a discussion of Alstom’s efforts in Philadelphia, see Holcomb, Henry
J. Powering Up For Tomorrow’s Ships. Philadelphia Inquirer, June 5, 2000.
41 General Dynamics owns 3 of the 6 shipyards that build major ships for the Navy – the
Electric Boat Corporation of Groton, CT and Quonset Point, RI, which builds nuclear-
powered submarines, Bath Iron Works Corporation of Bath, ME, which builds surface
combatants and amphibious ships, and National Steel and Shipbuilding Company (NASSCO)
of San Diego, CA, which builds auxiliary and sealift ships.
42 NNS, which is located in Newport News, VA, builds nuclear-powered aircraft carriers
and nuclear-powered submarines for the Navy.
43 Although the General Dynamics- and NNS-led teams are both developing electric-
drive systems featuring permanent magnet motors, there are numerous differences in these two
systems. For example, although both teams employ permanent magnet motors, the two teams
have taken different approaches to the design of the control mechanisms for the motors, which
is why the NNS-led team sometimes refers to its motor as a brushless DC motor.

CRS-33
Several U.S. Navy ship-acquisition programs are (or could be) associated with
the Navy’s electric drive program, including the following:
! DD-21 Land-Attack Destroyer Program. This is the Navy’s program to
develop and procure a next-generation surface combatant following the
completion of the current Arleigh Burke (DDG-51) Aegis destroyer
procurement program. The first DD-21 is to be procured in FY2005; a total
procurement of about 32 ships is envisioned. As mentioned earlier, the Navy
announced in January 2000 that the DD-21 will use electric drive. In light of
this announcement, as well as the size of the DD-21 program and the fact that
the DD-21 design is to form the basis of the Navy’s next-generation CG-21
cruiser (which is to be procured following completion of the DD-21 program,
perhaps sometime after FY2015), the DD-21 program is widely viewed as the
ship-acquisition program currently most closely and significantly associated
with the Navy’s electric-drive effort.44
! Virginia (Ssn-774) Class Attack Submarine Program. The first ship in this
program, previously known as the New Attack Submarine (NSSN) program,
was procured in FY1998. The second ship was procured in FY1999, and
current plans call for the next five ships to be procured at a rate of one per year
during the period FY2001-FY2005. A total of perhaps 30 ships might
eventually be procured. The current Virginia-class design uses a mechanical-
drive system, but there has been much discussion of building future units in the
class to a modified design that uses electric drive. Because of the potential size
of the program, and potential for the Virginia-class design to form the basis of
the Navy’s next-generation ballistic missile submarine (which might begin
procurement around 2020), the Virginia class program is also significantly
associated with the Navy’s electric-drive effort.45
! TADC(X) Auxiliary Dry Cargo Ship Program. This 12-ship program is
intended to provide replacements for several older Navy auxiliary ships. The
first TADC(X) was procured in FY2000. The second ship is to be procured
in FY2001, and the remaining 10 ships in the program are to be procured
during the period FY2002-FY2005.
! JCC(X) Joint Command and Control Ships. This program would replace
the Navy’s four aging command ships with a new class of four Joint Command
and Control (JCC[X]) ships. Under the Navy’s current plan, the first JCC(X)
is to be procured in FY2004.
! LHA Replacement Ship Program. This program would replace the Navy’s
5 aging Tarawa (LHA-1) class amphibious assault ships, which will reach the
end of their 35-year service lives during the period 2011-2015. The first of
44 For more on the DD-21 program, see CRS Report 97-700 F, Navy DD-21 Land
Attack Destroyer Program: Background Information and Issues for Congress, by Ronald
O’Rourke.
45 For more on the Virginia-class program, see CRS Report RL30045, Navy Attack
Submarine Programs: Background and Issues for Congress, by Ronald O’Rourke.

CRS-34
these ships, LHA-1, is to be replaced by LHD-8, which will be the eighth Wasp
(LHD-1) class amphibious assault ship. LHD-8 is currently planned for
procurement in FY2005, but its procurement could be accelerated to an earlier
year. Ships to replace LHAs -2, -3, -4, and -5 will be procured after LHD-8.46
! CVN(X) Program. The CVN(X) is the Navy’s planned next-generation
aircraft carrier. Under current Navy plans, the first ship in the program
(CVN[X]-1) is to be procured in FY2006 and the second (CVN[X]-2) in
FY2011.47
! Coast Guard Deepwater Project Cutter. The Deepwater project is an
ambitious Coast Guard program to replace its aging deepwater (i.e., far-from-
shore)-capable cutters and aircraft. Under the Coast Guard’s schedule for the
Deepwater project, the first new cutter would be procured in FY2002.48
Navy Report to Congress
The following is the executive summary of the Navy’s March 1999 report to
Congress on prospects for a common electric drive system for Navy ships, as
reprinted on pages 9 and 10 of the April 12, 1999 issue of Inside the Navy:49
The Navy evaluated electric drive alternatives for future submarines, surface
combatants, and aircraft carriers. A team of Naval Sea Systems Command
technical experts studied the feasibility of common electric components for
integrated power (electric drive) systems on DD-21, CVN (X), and a VIRGINIA
Class (NSSN) variant, and concluded the following:
–
a common motor, or multiples of a common motor, could
accommodate the range of main engine horsepower and shaft
speeds for surface combatants, aircraft carriers, and submarines;
–
generator commonality is limited to surface combatants and
submarines due to size and power requirement incompatibility
between these platforms and aircraft carriers; and
–
a common motor controller for all applications is not practicable,
however common subcomponents for all three applications is
feasible.
46 For more on LHD-8, see CRS Report RS20563, Navy LHD-8 Amphibious Assault
Ship: Background and Issues For Congress, by Ronald O’Rourke.
47 For more on the CVN(X) program, see CRS Report 98-359 F, CVN-77 and CVX
Aircraft Carrier Programs: Background and Issues for Congress, by Ronald O’Rourke.
48 For more on the Deepwater project, see CRS Report 98-830 F, Coast Guard
Integrated Deepwater System: Background and Issues for Congress, by Ronald O’Rourke.
49 For news coverage of Navy report, see Schweizer, Roman. Navy Wrestles With
Prospects, Price of Electric Drive for Subs, Ships. Inside the Navy, April 12, 1999: 8-9;
Holzer, Robert. U.S. Navy Strives To Electrify Future Combat Fleet. Defense News, April
5, 1999: 1, 50.

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For future aircraft carriers, there will be a need for an increased electric
generation capacity for loads such as an electric catapult and recovery system,
future electrically powered weapons, and countermeasures. With this in mind, the
Naval Sea Systems Command has studied options for electric drive and increased
electric generation capacity. These studies concluded that while electric drive was
feasible, mechanical drive is more appropriate at this time. For a ship the size of
an aircraft carrier, electric drive did not offer space or weight savings over a steam
driven mechanical drive design with appropriately sized turbine generators. In
addition, the studies found that the most affordable method to achieve the objective
of increased electric generating capacity was to use mechanical drive with larger
turbine generators.
A Navy integrated power systems development program, which demonstrates
a full size induction motor and other components for potential use in future surface
ships, is entering the full-scale system test phase. This motor would not be
appropriate for submarine use because it does not have the power density or
acoustic performance needed for submarine applications.
The Navy has done extensive work to assess the viability of superconducting
direct current (DC) homopolar motors for electric drive. However, there are
significant technical challenges associated with homopolar motors. While come
progress has been made in overcoming these challenges, more work is required. As
a result, superconducting homopolar motors are not considered a viable option for
electric drive at this time.
The Navy has concluded that the radial-gap permanent magnet motor
possesses the power density, acoustic performance, and maturity of technology to
be a viable propulsion motor common to the broadest range of ships. We believe
that this is now possible due to the recent advancements in technology which are
being pursued by industry in developing propulsion motors based on permanent
magnet motor technology.
The Navy recognizes that a common development program would benefit
both future surface combatants and submarines. Such a corporate program would
allow the Navy to maximize life cycle cost reductions while satisfying performance
needs of the broadest range of platforms. Common technology presents an
opportunity for a common support structure such as personnel, training and
maintenance facilities.
A Navy corporate integrated power system development program will benefit
future ships, and allow horizontal integration of technology, components and
training across the broadest range of ships. Therefore, the Navy is currently
considering an expansion of its integrated power systems development to a
corporate Navy program including state-of-the-art permanent magnet motor
technology. Our plan includes an aggressive evaluation of the application of these
technologies and the benefits associated for each type of platform including life
cycle cost, logistics, and training reductions.
A summary comparison of mechanical drive versus an integrated power system
(electric drive) is provided in Table I.

CRS-36
Table I - Mechanical vs. Integrated Power System Comparison
Mechanical
Integrated
Integrated
Integrated
Drive
Power System
Power System
Power System
with Induction
with Permanent
with Homo-
Motor
Magnet Motor
polar Motor
Sub-
– Does Not
– Does Not
+ Meets Future
– Significant
marine
Meet Future
Meet Future
Acoustic Goals
Technology
Acoustic Needs
Acoustic Goals
Development
+ Meets Motor
Required
– Required
Size
Induction Motor
Requirements
Size Is Too
large
+ Commonality
Is possible
Surface
– No Fuel
+ Provides
+ Commonality
– Significant
ship
Economy
Flexible Power
Is possible
Technology
Improvement
Distribution
Development
+ Provides
Required
– No Flexible
+ Provides
Flexible Power
Power
Naval
Distribution
Distribution
Architectural
Flexibility
+ Provides
Naval
+ Life Cycle
Architectural
Cost Savings
Flexibility
+ Lower
+ Life Cycle
Development
Cost Savings
Risk than
Permanent
Magnet Motor
– Commonality
Not Possible
– Motor Larger
than Permanent
Magnet Motor
Aircraft
+ Future Power
+ Potential to
+ Potential to
– Significant
Carrier
Generation
meet future
meet future
Technology
Needs Can Be
goals
goals
Development
Met With New
Required
Electric Plant
– Not Cost
– Not Cost
effective for
effective for
+ Most
CVN (X)
CVN (X
Affordable
Carrier
Alternative

CRS-37
Note that the table does not specifically address electric-drive systems featuring
a regular (non-superconducting) synchronous motor (like those in the commercial
electric-drive systems currently operating on cruise ships and other ships) or a
superconducting synchronous motor.
Congressional Reaction to Navy Report
In marking up the Administration’s proposed FY2000 defense budget, the House
Armed Services Committee stated the following in reaction to the Navy’s March 1999
report:
The committee notes the Navy’s increased interest in the development of
electric drive propulsion technology and the potential use of electric drive
propulsion in future surface combatants and submarines, including insertion of an
electric drive propulsion system in the DD-21 land attack destroyer and in the New
Attack Submarine (NSSN) programs. A common integrated electric drive system
appears to offer significant advantages, however, implementation of such a system
has been limited by the technology needed for reliable electric motors of the power
(approximately 30,000 to 50,000 shaft horsepower (shp)) required. The
committee is aware that several alternative electric propulsion motor concepts have
been proposed that are of varying degrees of technical maturity.
The statement of managers accompanying the conference report on H.R.
4103 (H.Rept. 105-746) directed the Secretary of the Navy to provide a report to
the Congress which evaluates the installation of a common integrated electric drive
system for DD-21, a NSSN variant, and [also evaluates designs for] the next-
generation CV(X) aircraft carrier with both a common integrated electric drive
system and a conventional mechanical drive system. The Secretary’s report, dated
March 1, 1999, states that the Navy has concluded that the radial-gap PM
[permanent magnet] motor possesses the power density, acoustic performance, and
maturity of technology to be a viable propulsion motor common to the broadest
ranges of ships and that the Navy is currently considering expanding its IPS
[Integrated Power Systems] development [program] to a corporate Navy program
that will include state-of-the-art permanent magnet motor technology....
The committee will consider recommendations by the Secretary for further
development and demonstration of electric drive propulsion technology for Navy
ships which identify necessary funding and provide a program plan for
development.50
The Senate Armed Services Committee, in its markup, stated that the Navy’s
integrated power systems development effort
is designed to explore technologies required to develop power systems that could
provide innovative means of generating, controlling, distributing, and using
electricity in future ships. Propulsion motor development is a central focus of
these explorations by the Navy and, independently, by commercial entities.
50 H.Rept. 106-162 of May 24, 1999 (House Armed Services Committee Report on H.R.
1401, the FY2000 defense authorization bill), p. 194-195.

CRS-38
A recent Navy report entitled A Report to Congress on Navy Common
Integrated Electric Drive Systems, addressed electric drive alternatives for future
submarines, surface combatants, and aircraft carriers. The study reached several
conclusions, to include: (1) the radial-gap permanent magnet motor has the power
density, acoustic performance, and maturity of technology to be a viable
propulsion motor common to the broadest range of ships; and (2) superconducting
homopolar motors are not considered a viable solution for electric drive at this
time. The committee believes that broad application is an important aspect of
reducing life cycle costs to make the fleet of the future more affordable.
The committee understands that the Navy is considering an expansion of the
integrated power system program to include permanent magnet motor technology.
The committee encourages the Navy to take this step, however, the committee also
expects the Navy to continue the technology base investment in superconducting
alternatives as well, despite the fact that these technologies will not be mature
enough for immediate applications such as DD-21.51
Issues for Congress
Electric-drive presents several potential issues for Congress that can be divided
into two groups: those relating to electric-drive technology in general, and those
relating to the potential application of electric drive to specific ship-acquisition
programs. Each of these is discussed below.
Electric Drive in General
Electric Drive as a Technology Area. Although electric drive is often
discussed as a specific system that could be available in the near future for the DD-21
program, many elements of electric-drive technology have the potential to evolve and
improve over time. This suggests that policymakers might consider addressing
electric drive as not simply a proposal for a specific system that might require a few
nearer-term acquisition decisions, but as a broader technology area that might require
longer-term management and oversight and a series of research, development, and
procurement decisions stretching over the course of several years.
Given the many (and in some cases competing) possibilities for evolving and
improving electric-drive technology over time, conducting longer-term management
and oversight of electric drive as a technology area might be assisted by developing
an electric-drive technology development roadmap or master plan extending perhaps
10 to 25 years into the future. Such a roadmap, updated periodically, could help
place nearer-term investment decisions regarding electric-drive technology in the
context of potential longer-term opportunities, risks, benefits, and implications. In
recent years Congress has called for (and DoD has provided) master plans or
roadmaps in other naval technology-development areas, such as mine warfare and
anti-submarine warfare, that present multiple development opportunities stretching
out over a period of several years.
51 S.Rept. 106-50 of May 17, 1999 (Senate Armed Services Committee Report on S.
1059, the FY2000 defense authorization bill), p. 232-233.

CRS-39
Near-Term Costs. As noted in the background section, pursuing electric-drive
will incur higher near-term costs than a strategy that places continued emphasis on
mechanical-drive technology.
With regard to development costs, mechanical-drive propulsion for naval ships
is a very mature technology and would not necessarily require substantial amounts of
additional research and development funding for future naval ships.52 Developing
electric-drive technology for warships, in contrast, would require hundreds of millions
of dollars in research and development funding in coming years, particularly if the
technology is developed for submarines as well as surface ships, and if development
of more advanced electric-drive technologies is pursued.
With regard to production costs, several (but not all) sources for this report
stated that electric-drive systems initially would be more expensive to procure than
mechanical-drive systems.53 Although there are no precise figures, information
provided by some sources suggest the procurement cost of a non-commercial (Navy-
developed) electric-drive system might add a few tens of millions of dollars to the
total procurement cost of a Navy combat ship. An additional cost of, for example,
$15 million to $50 million would equate to an increase of about 2 percent to 6 percent
in the procurement cost of a surface combatant costing about $800 million (the
approximate target cost in FY2001 dollars of a DD-21 class land-attack destroyer),
or about 1 percent to 3 percent in the procurement cost of an attack submarine
costing about $2 billion (the approximate current cost of a Virginia [SSN-774] class
submarine). The cost premium for a commercial electric-drive system (which, as
discussed below, might be suitable for use in a Navy auxiliary ship) could be less than
that of a Navy-developed system that is engineered to be more power-dense, quiet,
and shock-resistant.
These sources, however, agreed that the procurement cost of electric-drive
systems would come down over time if more systems are procured and production
economies of scale for electric-drive technology increase, and as electric-drive
technology continues to improve. They also agreed that the higher initial costs of
electric-drive systems (both development and procurement) would be more than offset
over the longer run by reduced ship life-cycle operating and support costs.
Measuring and Assessing Cost Effectiveness. Several sources agreed that the
cost-effectiveness of electric drive should be examined not by focusing on the electric-
drive system or any of its components in isolation, but rather by examining the effect
that electric drive has on overall ship cost and capability. Focusing on the electric
drive system or any of its components in isolation, they stated, could overlook certain
effects of electric drive on total ship cost and capability and encourage optimization
of the design at the system or subsystem level rather than the total-ship level.
52 An exception would be if a decision were made to attempt to achieve significant
further improvement in the quieting of mechanical drive technology. Such an effort could
require significant additional research and development funding.
53 Some sources disagreed, stating that electric-drive would be roughly as expensive to
procure as mechanical-drive technology, and perhaps (a couple of sources stated) somewhat
less expensive.

CRS-40
In view of the potential for electric-drive technology to be applied across
multiple ship types, and of the proposal for a common electric drive system (or
common family of components), it might also be said that the cost-effectiveness of
electric drive might best be measured not only in terms of its effect on the total costs
and capabilities of individual ship designs, but also in terms of its effect on total fleet
costs and capabilities. In this view, just as it would be inappropriate to optimize the
application of electric drive at the system or subsystem level, so too it might be
insufficient to assess the cost-effectiveness of electric drive at the level of individual
ship designs. Such an approach may obscure the advantages of certain strategies for
applying electric drive on a fleet-wide basis. In particular, it is possible that an
electric-drive system that results in a suboptimal design for a particular kind of ship
may nevertheless enable a more optimal application of electric drive across multiple
ship types.
Since some of the most important projected potential benefits of electric drive
technology, such as ship life-cycle fuel savings, would accrue over many years, any
newly developed estimates of the costs and benefits of electric-drive technology
should arguably include not just shorter-term issues such as initial research and
development and procurement costs, but also measures that examine longer-term (i.e.,
life-cycle or total ownership) costs and warfighting effects as well.
Although electric-drive technology offers numerous potential cost and
warfighting benefits for Navy ships, relatively few precise estimates are available on
the magnitude of these benefits. Many of the available estimates, moreover, are
single-point estimates that relate to the potential costs or benefits of a particular
electric-drive technology concept as applied to a particular kind of ship under a
specific set of assumptions regarding ship service life and typical ship operating
speeds.
The scarcity of estimates that are both precise and systematic (rather than rough
or single-point) is currently providing ample room for firms involved in developing
electric-drive technology to make well-intentioned but also self-interested and
sometimes-conflicting presentations to policymakers on the technology. If not
redressed, the scarcity of precise and systematic estimates will make it difficult for
policymakers to assess with any precision the potential cost-effectiveness of electric-
drive technology in general and (probably more significant) the relative cost-
effectiveness of differing technical approaches to achieving electric drive,
incorporating it in the fleet, and improving it over time. As a result, policymakers
would have more difficulty making decisions concerning electric drive, particularly
decisions relating to longer-term development of the technology following an initial
application to the fleet. More precise and systematic estimates may be produced by
a study on electric drive that is being done for the Navy by the Rand Corporation and
the Center for Naval Analyses.54
The Navy’s interest in electric-drive technology is consistent with the decisions
of commercial ship operators (especially cruise ship operators) and other navies in
54 Castelli, Christopher J. Navy Plans To Study Potential of Electric Drive for Ships and
Subs. Inside the Navy, December 28, 1998:1, 10.

CRS-41
recent years to move to electric-drive technology for their own ships. The
commercial ship industry’s shift from mechanical- to electric-drive technology
suggests that electric drive offers demonstrated advantages, at least for large ships,
in areas such as reduced fuel costs, increased payload space (for cruise ship operators,
this can translate into additional passenger cabins or other revenue-generating spaces),
and perhaps reduced propulsion plant noise.
The strong interest in electric drive by other navies (particularly in Europe), and
the reasons they have identified for pursuing the technology, provide support for the
argument that electric drive offers a variety of warfighting and life-cycle cost
advantages for naval ships. The British Navy’s interest in electric drive is particularly
noteworthy not only because of the variety of ships that the United Kingdom is
considering to equip with electric drive, but also because the British Navy in the past
has adopted (or invented) important naval technologies that were later adopted by the
U.S. Navy.
The interest shown by other navies in electric drive, however, also demonstrates
that there are multiple technical approaches that can be pursued. For example, both
the 1998 NATO report and the British Navy’s development program highlight the
transverse-flux version of the permanent magnet motor as well as the radial gap (i.e.,
radial-flux) version, while permanent magnet motor efforts in the United States focus
more exclusively on the radial-gap version. There are also actual or potential
differences between the U.S. and European approaches to other components of
electric drive, such as the ship-wide electrical power distribution system. Thus, while
the interest shown by other navies in electric drive tends to support the U.S. Navy’s
interest in pursuing the technology, it also arguably underscores the need to carefully
evaluate the relative merits of different technical approaches.
Technical Risk. As noted in the background section, incorporating electric-
drive (rather than mechanical-drive) technology into Navy ship-acquisition programs
could add technical or schedule risk to those programs, since electric-drive technology
is less mature than mechanical-drive technology for application on naval ships. The
potential amount of technical or schedule risk varies, depending on the exact
configuration of the system in question. More advanced approaches to electric drive
(e.g., those involving more advanced types of motors and motor drives) present
greater potential technical or schedule risk, but also promise greater potential cost
effectiveness.
In general, electric-drive components presenting potential technical or schedule
risk include, among others,
! motor drives – which some sources identified as perhaps the foremost item of
development risk,
! motors – whose development risk has been widely discussed,
! generators – if more advanced generator designs are pursued,
! the electrical distribution system,
! advanced propeller/stern configurations – if these are pursued, and
! overall system design and integration.
Issues to be addressed include:

CRS-42
! demonstrating at full scale technologies that to date have been demonstrated
at partial scale,
! improving thermal performance (i.e., preventing the overheating of increasingly
power-dense components),
! achieving desired levels of acoustic quieting and shock resistance, and
! designing overall system interfaces, controls, and module specifications,
particularly for achieving system modularity and commonality and built-in
potential for evolution and upgrades.
Some of the risks involved in developing electric-drive technology have been
mitigated by the successful development of electric-drive technology for commercial
ships. Some industry sources argued that the amount of remaining risk involved in
developing electric drive for Navy use is low to moderate, and that development of
electric drive poses less risk than has been posed by other technologies that the Navy
has successfully developed. Other sources suggested that the degree of risk may be
higher (moderate or even potentially high risk in some respects), particularly if the
technology is developed on an aggressive (i.e., compressed) schedule.
The degree of technical risk involved in developing electric drive might be
mitigated through more intensified research and development. Given the number of
specific development possibilities that currently exist in electric-drive technology, the
amount of research and development funding that until recently has been programmed
for the area, and the potential cost and warfighting benefits of electric drive, an
argument can be made that electric drive technology could be further elevated in
priority as an element of the Navy’s research and development account.
Electric drive, however, is by no means the only promising technology area for
the Navy. If the Department of the Navy’s overall budget (or its research and
development budget) remains relatively stable, applying significantly more funding to
research and development work on electric drive might come at the expense of other
promising Navy technology programs. The potential implications for other Navy
programs of providing increased funding might underscore the need for developing
an electric-drive technology investment roadmap and more precise and systematic
measures of the potential costs and benefits of electric drive technology.
Common System. As noted earlier, the Navy stated in its March 1999 report
to Congress 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 Navy and the other military services have used the concept of commonality
in numerous other equipment-acquisition programs over the years as a means of
satisfying operational requirements in the most efficient manner possible. To cite just
a few key examples, the Navy has long had common guns, missiles, weapon
launchers, radars, sonars, computers, communication systems and other electronic
systems that are installed across a variety of ship classes. In the area of ship
propulsion, a single type of nuclear reactor (the S5W) was once used to power
various Navy submarine classes, and a single type of gas turbine engine (the LM2500)
has been used as the prime mover for every class of major surface combatant that the
Navy has built since the 1970s. As the Navy has declined in size during the 1990s,

CRS-43
Navy leaders have placed even greater emphasis on achieving commonality of key
equipment across ship classes as a means of preserving economies of scale in
equipment development, procurement, and life-cycle operation and support.55
Potential advantages of a common electric-drive system (or a family of common
components) for application to both submarines and various surface ships include:
! nearer-term cost savings due to streamlining of research and development
costs (i.e., avoidance of parallel development of differing electric-drive
systems);
! both nearer- and longer-term savings due to greater efficiencies in procurement
(i.e., achieving maximum economies of scale in the production process by
producing larger numbers of a single system or family of components); and
! longer-term savings due to the streamlining of fleet training, operation and
support efforts (i.e., maintaining common training, maintenance, and logistical
support systems for all Navy ships equipped with the system).56
The potential nearer-term savings are difficult to estimate due to the scarcity of
precise and systematic cost estimates for researching and developing various potential
technical approaches to electric drive. On the basis of preliminary cost information
provided by sources for this report, however, it appears that the savings could easily
total in the millions of dollars, and could, depending on the potential scope of avoided
parallel development efforts, run into the tens or even hundreds of millions of dollars.
The potential long-term savings of pursuing a common system or family of
components are similarly difficult to estimate due to both the relative scarcity of
precise and systematic cost estimates for producing, operating, and supporting ships
equipped with differing forms of electric drive, and uncertainty concerning how many
classes of ships might be equipped with the technology, and when. Navy experience
with other major acquisition programs, however, suggests that longer-term savings
due to improved economies of scale in production and the streamlining of training,
operation and support systems could be substantial.
The concept of developing a common system or family of components poses at
least two potential policy issues for the Navy and Congress. One concerns the extent
of commonality across electric-drive-equipped Navy ships; the other concerns the use
of competition in the development and procurement of electric-drive technology.
55 See, for example, Schweizer, Roman. Requirements Chiefs Approve Plan to Focus
Common Technology Development. Inside the Navy, September 29, 1997, and Schweizer,
Roman. Requirements Chiefs Consider Pooling Money to Develop Common Components.
Inside the Navy, September 15, 1997.
56 For an article discussing the potential benefits of a common electric-drive system, see
Bartlett, E. L., Jr. Electric Propulsion: Commonality Is the Only Way. U.S. Naval Institute
Proceedings, August 1998: 71-73.

CRS-44
Extent of Commonality. The concept of developing a common electric-drive
system or family of components for all electric-drive-equipped Navy ships is
sometimes posed, tacitly if not explicitly, as an alternative to developing a different
electric drive system for each kind of Navy ship to be powered by electric drive.
These two approaches, however, are simply two options at opposite ends of a
spectrum of acquisition options that also includes mixed approaches that would
combine elements of commonality with elements of ship-specific solutions. One
example of a mixed approach would be to equip most types of ships with one kind of
electric drive system while equipping one or more other types of ships with a different
kind. Another example would be to install certain components as common elements
across the fleet while permitting other components to vary more fundamentally by
ship type. The Navy’s March 1999 report appears to suggest that the second of these
approaches may have merit.
Should agreement be achieved to broadly pursue electric drive, the goal for
policymakers would be to optimize the cost-effectiveness of electric drive as it is
applied across the fleet. Past acquisition experience clearly suggests that designing
a unique electric-drive system for each kind of ship would not result in the most cost-
effective application of electric drive across the fleet. Past experience, however, does
not prove conclusively that it would be achieved by an approach that would install a
common system or family of components on every kind of ship that is scheduled to
be powered by electric drive.
Just as there are numerous kinds of equipment in the Navy that are installed in
identical or near-identical form on various classes of ships, so too are there examples
of equipment that differ significantly in design from one kind of ship to the next.
Some cases of equipment differentiation across ship types are likely due to either a
reduced emphasis in previous years on achieving the benefits of commonality or
conscious decisions to continue operating non-conforming “legacy” systems on some
ships because these systems would be expensive to replace. Other cases of equipment
differentiation across ship types, however, might reflect a judgment that a maximally
common approach was not the optimum solution on a fleet-wide basis. In the case
of ship propulsion equipment, differentiation across the fleet in the past has resulted
from differences across ship types in factors such as ship size, mission, or operational
cycle.
From a public-policy perspective, commonality is not an end in itself but rather
a strategy that policymakers would consider as they sought the most cost-effective
path to apply electric-drive technology across the fleet. In seeking this path,
policymakers might wish to assess the relative merits of both a maximally common
approach and more mixed approaches. A technology-development roadmap or
master plan and more precise and systematic estimates of the costs and benefits of
various technical approaches to electric drive could keep the potential value of
commonality in perspective and help policymakers identify the best overall path for
the fleet.
Competition. If policymakers chose an acquisition strategy for electric drive
featuring maximal or near-maximal commonality across ship types, a second potential
issue to consider would be the role of competition in the development and
procurement of electric-drive technology. Pursuing a common electric-drive system

CRS-45
or family of components could in theory lead to the emergence of a dominant or
monopoly supplier to the Navy of electric-drive technology, components, and
systems. Such a development could inhibit if not preclude the Navy from using
competition in the development and procurement of follow-on electric-drive
technology.
In light of this possibility, policymakers who place a high value on the use of
competition in defense development and procurement – to secure benefits in
restraining cost, improving product quality, encouraging adherence to scheduled
delivery dates, and promoting innovation – might wish to consider measures aimed
at ensuring that the Navy’s acquisition strategy for electric drive makes maximum use
of competition among industry approaches prior to selecting an approach that would
form the basis for the common system. They also might consider actions aimed at
ensuring that nearer-term acquisition decisions, including the selection of a common
system or family of components, preserve, as much as possible, a potential for
employing competition in the eventual development and procurement of follow-on
electric-drive technologies, components, and systems.
One possible approach for preserving a potential for competition in follow-on
development and acquisition in electric drive would be to require the common electric
drive system to be designed to a so-called open architecture – a set of nonproprietary
and nonexclusive technical standards for key system characteristics that would permit
firms other than those making the current system to compete on an equal footing with
those making the current system for the development of follow-on technologies,
components, or systems. This approach is now being used in other defense
acquisition programs, particularly those involving electronic systems.
Another possible approach, not mutually exclusive with the previous one, would
be to provide some amount of support to firms other than those who supply the
current electric-drive system to finance continued development of potential competing
technologies or components that are currently considered less mature or more risky
than those used in the current common system. Providing such support would reduce
the research and development savings associated with pursuing a common electric
system or family of components, but would help bring to maturity alternative technical
approaches that could be more cost effective than those that can be pursued today.
Financially supporting potential downstream competitors and competing technologies
could maintain a wider set of alternatives and some degree of competitive leverage
for the federal government over the longer run as it sought to improve its electric-
drive technology in step with technological advancements.
Motors. Much of the debate since 1998 over the application of electric-drive
technology to U.S. Navy ships concerns the type of electric motor that should be
used. Indeed, within the overall debate over electric-drive technology, perhaps no
one issue has been more contentious. The issue is highly charged because specific
motor types are associated with specific firms competing for a part of the Navy’s
electric-drive program. A preference for a certain motor type can thus lead to a
preference for the proposal of one firm or industry team over that of another.
As mentioned in the background section, the electric motors associated with
electric-drive systems for large ships can be divided into five basic categories –

CRS-46
synchronous motors, induction motors, permanent magnet motors, superconducting
synchronous motors, and superconducting homopolar motors. Each of these is
discussed below.
Synchronous Motor. Of the basic motor types considered here, the synchronous
motor can be considered the most mature technologically in application to large ships.
It is the type currently used on most electric-drive-equipped commercial ships,
particularly cruise ships, where it has been used successfully for more than a decade.
There is a consensus among both naval and industry sources that the
synchronous motor, if scaled up to the higher horsepower ratings needed to move
surface combatants and submarines at high speeds (i.e., 30+ knots), would be too
large and heavy to be suitable for use on these ships. The synchronous motor, in
other words, is considered insufficiently power-dense for application to these ships.
Space and weight is a critical design consideration in the design of submarine
propulsion plants. While space and weight considerations might be more relaxed in
the design of a surface combatant’s propulsion system, a high-horsepower
synchronous motor is considered too large to fit into a podded propeller.
The synchronous motor can be made somewhat smaller and more power-dense
through the application of water cooling (as opposed to air cooling). This approach,
however, appears to be receiving no attention in industry efforts to develop electric-
drive technology for the U.S. Navy, perhaps because the potential gain in power
density is not deemed large enough to justify the effort.
The most likely apparent opportunity for incorporating electric-drive systems
using synchronous motors into the Navy’s electric-drive effort would be to install
them in large Navy auxiliary ships. Compared to surface combatants and submarines,
auxiliary ships are often designed for lower maximum speeds, their internal space
constraints may not be as great, and their propulsion systems might not need to meet
the same acoustic-quieting or shock-resistance standards. Consequently, it might be
feasible to equip auxiliary ships with commercial electric-drive systems using
moderate-horsepower synchronous motors that have already been developed for use
on cruise ships.
Using a commercially available electric-drive system on an auxiliary Navy ship
would raise an issue concerning the extent of commonality of electric-drive
technology on U.S. Navy ships. Equipping auxiliary ships with commercial systems
using synchronous motors would differentiate them from Navy ships using technology
developed specifically for U.S. Navy use and thus reduce commonality in electric-
drive technology within the U.S. fleet. It would also, however, make these auxiliary
ships common in their electric-drive technology to cruise ships and other commercial
ships, and permit them to take advantage of the economies of scale that exist for the
production and life-cycle support for these systems, thus recouping at least some (and
possibly much) of the cost-related benefits that commonality within the Navy would
achieve. In addition, if future Navy auxiliary ships are built to more commercial (as
opposed to U.S. Navy military) standards of construction, which is an option of
growing interest to the Navy, it might be viewed as appropriate to equip these ships
with commercial (as opposed to military) electric-drive technology.

CRS-47
Since today’s commercially available electric drive systems are made by
European firms, using a commercially available electric-drive system on an auxiliary
ship could raise an issue regarding use of foreign-made propulsion technology on a
U.S. Navy ship. Using a European-made commercial electric-drive system on a U.S.
Navy ship might be viewed as acceptable in terms of contributing to a broader two-
way U.S.-European trade in defense-related systems. Policymakers, however, have
traditionally been highly resistant to the idea of relying on foreign-made technology
in the construction of U.S. Navy ships (and many other major U.S. military platforms
and weapons), in part on the grounds that it introduces a risk that unforeseen
developments in a foreign country could delay or disrupt a U.S. shipbuilding program
or complicate efforts to support these ships once they are in service, particularly in
time of crisis or conflict.
Although U.S.-based firms involved in electric-drive technology development so
far have chosen not to develop competing systems engineered to commercial
performance specifications, commercial electric-drive systems in the future could still
be built and supported in the United States, either by a U.S. subsidiary of a European
firm or by a U.S. firm on license from a European firm. This could reduce any risk
associated with using a European-developed commercial electric-drive system.
Induction Motor. The induction motor is generally considered the second-most
mature motor type for application to large ships, after the synchronous motor.57 As
discussed earlier, it is the type of motor used in the Navy’s land-based full-scale
electric-drive demonstration system in Philadelphia.
The induction motor can be made significantly more power-dense than the
synchronous motor. Most of the sources consulted for this report argue (or do not
contest) that it can be sufficiently power-dense to be suitable for use on U.S. Navy
surface combatants. By the same token, however, most sources – including the U.S.
Navy in its March 1999 report to Congress – also argue (or do not contest) that the
induction motor is not sufficiently power-dense or quiet to be suitable for use on U.S.
Navy submarines.
Because the induction motor is generally considered more mature technologically
at this point than the permanent magnet motor or superconducting motors, using an
electric-drive system with an induction motor might help mitigate the risk of
integrating electric-drive technology into the DD-21 program. Since the induction
motor is not considered suitable for use on U.S. Navy submarines, however, using it
on the DD-21 would preclude achieving motor commonality across surface ships and
submarines in the Navy’s electric-drive program.
In addressing the commonality issue, one potential issue for policymakers would
be whether an electric-drive system for the DD-21 using an induction motor could be
designed so that it preserved commonality with submarines in components other than
the motor. Another would be whether the DD-21 system could be designed so that
57 The induction motor discussed here is sometimes called the advanced induction motor
to distinguish it from earlier, less sophisticated induction motors.

CRS-48
the induction motor could later be changed to a permanent magnet or
superconducting motor.
Using the induction motor on the DD-21 or other ships would similarly raise a
potential issue regarding use of foreign-developed technology, since this motor has
been developed by a European-based firm (Alstom) while U.S. firms are focusing on
developing permanent magnet and superconducting motors. As noted earlier,
however, Alstom is the supplier of the induction motor (and other components) of the
U.S. Navy’s land-based electric-drive demonstration system and has established U.S.-
based subsidiaries in Pittsburgh and Philadelphia to support its electric-drive efforts
for the U.S. market.
Permanent Magnet Motor. The permanent magnet motor can be made quieter
and significantly more power-dense than the induction motor – enough so that it is
consequently considered suitable for use on submarines as well as surface combatants.
As a consequence, the Navy and other sources generally agree that the permanent
magnet motor can be used in a common electric drive system for Navy surface ships
and submarines. As noted earlier, the Navy’s March 1999 report to Congress focuses
on the permanent magnet motor as the motor available in the nearer term that would
be suitable for a common electric-drive system. Both the 1998 NATO report and the
British Navy’s current advanced electric-drive development effort similarly focus on
the permanent magnet motor.
The permanent magnet motor is less mature technologically than the induction
motor, and consequently at this point may pose more development risk to incorporate
into a nearer-term ship-acquisition program such as the DD-21 destroyer. In contrast
to the induction motor, a version of which is being tested in full-scale form at the
Navy’s land-based test site, the permanent magnet motor will be tested in quarter-
scale (6,000-horsepower) form on LSV 2 (Large-Scale Vehicle 2), also known as the
Cutthroat – the Navy’s approximately one-quarter scale unmanned submarine for
testing technologies for possible use on the Virginia-class submarine and other future
submarines.58 The Navy’s decision to use a permanent magnet motor as the
propulsion system for this important test vehicle reflects a certain amount of Navy
confidence in permanent magnet motor technology, at least in quarter-scale form.
Sources differ regarding the amount of technical risk involved in scaling up the
permanent magnet motor to full size. Firms involved in developing permanent magnet
motor technology argue that the basic technological issues in permanent magnet
motors have been resolved, and that scaling up the technology will not pose any new
issues. Other sources, including firms involved in developing other types of motors,
demur, arguing that scaling up is never risk-free.
A key issue at this point is whether the permanent magnet motor will be
sufficiently mature for timely incorporation into the lead ship in the DD-21 class. The
Navy’s decision, announced in February 2000, to delay the procurement of the first
DD-21 by one year (to FY2005) will, other things held equal, reduce the risk
58 Costa, Keith J. Newport News, Electric Boat To Outfit Test Sub With Electric Drive.
Inside the Pentagon, February 25, 1999: 15.

CRS-49
associated with equipping the first DD-21 with an electric-drive system using a
permanent magnet motor. Under the previous plan to procure the first DD-21 in
FY2004, most sources agreed that the time line for developing the permanent magnet
motor for the lead ship would have been challenging. The additional year relaxes the
situation somewhat, though much will still depend on the intensity of the development
work that is conducted on the motor (which will depend in part on the amount of
funding applied to the work), and on whether unforeseen issues arise in scaling up the
technology.
If the permanent magnet motor is deemed not mature enough to install on the
first DD-21, then policymakers could face the issue of whether the later ships in the
DD-21 program should be built with the permanent magnet motor (when it matures),
and whether earlier ships in the program built that are built with a different kind of
motor (presumably an induction motor) should be backfitted with the permanent
magnet motor at some point during their life. Addressing these issues could involve
weighing the potential benefits of maintaining electric-drive component commonality
within the DD-21 class against the potential benefits of commonality between the DD-
21 class and other, subsequent, Navy ship classes that are equipped with electric
drive.
U.S. (as well as European) firms are developing electric-drive systems using
permanent magnet motor technology. The U.S. Navy can thus develop and procure
an electric-drive system using permanent magnet motors without necessarily raising
issues associated with use of foreign-made or foreign-developed technology.
As noted earlier, both the 1998 NATO report and the British Navy’s
development efforts focus to some degree on the transverse-flux version of the
permanent magnet motor, as opposed to the radial-gap version being developed by
U.S. firms. This raises a potential issue for Congress as to the relative risks and
merits of the transverse-flux and radial-gap versions, and whether the U.S.
development efforts should include more work on the transverse-flux version.
Supporters of the transverse-flux version believe it to be the most efficient design, but
some sources stated that it may pose greater development risks than the radial-gap
design.
Some sources for this report, particularly supporters of other motor types, raised
a particular technical issue regarding permanent magnet motors that they argued
poses an elevated danger in the event of an internal fault (i.e., a short-circuit) in the
stator windings – a problem that can occur in an electrical motor. The issue arises
because it is not possible in a permanent magnet motor, as it is in other motor types,
to turn off the motor’s magnetic field.59 This, they argued, creates the potential for
a permanent motor to act as a generator in the event of an internal winding fault,
particularly if the fault occurs as the ship is moving through the water at some speed.
59 In a permanent magnet motor, the magnetic field that interacts with the electrical flow
to create mechanical movement is created by permanent magnets that are built into the rotor.
The magnetic field thus continues to exist when electrical power to the motor is cut off. On
other motor types, the magnetic field is created as a product of electrical energy flowing
through the motor, and ceases to exist when power to the motor is cut off.

CRS-50
This situation, they argued, would create a flow of electrical energy that would be fed
by the motor back into the fault, exacerbating the damage caused by the fault.60
Supporters of the permanent magnet motor stated that they are well aware of
this issue. For most kinds of internal faults, they stated, it will not be necessary to
turn off the magnetic field, because these faults can be managed through the design
of the motor and motor controller. For one kind of fault (a turn-to-turn short), they
stated, an ability to turn off the magnetic field could be useful, but the permanent
magnet motor can cope with this fault by stopping or slowing its rotation through use
of the same dynamic braking action as would be employed in the first stage of a
“crashback” scenario.61 In sum, they argued that the issue of dealing with an internal
fault, while real, can be addressed through careful system design and operation.
Some sources for this report also argued that the long-term stability of the
material used for the permanent magnets is not proven in large-ship propulsion motors
and could lead to reliability and maintenance issues over the life-cycle of the motor.
Supporters of permanent magnet motors argued that permanent-magnet motors in
industry use have proven themselves reliable over lengthy operating periods in other
applications and that the careful motor design can make permanent magnet motors
easier to maintain than existing electric motors.
Superconducting Synchronous Motor. The superconducting synchronous
motor employs superconducting technology (including cryogenic equipment to cool
the superconducting wire down to the temperatures at which the wires become
superconducting) to achieve significantly stronger magnetic fields than non-
superconducting motors. As a result, supporters of this motor type argue, the
superconducting synchronous motor, if developed, can be more power-dense – and
also quieter and more energy-efficient – than a permanent magnet motor.62 The U.S.
60 Electrical motors, which convert electrical into mechanical energy, can also, if
operated differently, act in the reverse manner – as generators that convert mechanical energy
into electrical energy. The sources argued that in the event of a winding fault, even when
electrical power to the motor could be cut off, the rotor would continue to spin for some time
under its own momentum. As the rotor, with its permanent magnets, continued to spin past
the stator, with its windings, an electrical current would be created that could flow back into
the winding fault, causing additional heat and damage to the motor. This scenario, some
sources argued, would be particularly relevant if the ship were moving at some speed, because
the ship’s continued forward movement would cause the now-unpowered propeller to rotate
as a result of the ship’s forward movement through the water. This rotation would be fed by
the propeller shaft back into the motor, causing the rotor to spin even longer than it would
simply as a result of its own momentum.
61 A crashback scenario is when the motor is commanded to go immediately from full
ahead to full reverse. In accomplishing this, the system employs dynamic braking, in which
electrical energy is drained from the motor so as to produce a reverse torque that helps bring
the motor to a stop.
62 See, for example, Whitcomb, Clifford A. Commercial Superconducting Technology
for Ship Propulsion. The Submarine Review, April 2000: 62-73; Kalsi, S., B. Gamble, and
D. Bushko. HTS Synchronous Motors For Navy Ship Propulsion. Paper presented at Naval
(continued...)

CRS-51
firm developing the superconducting synchronous motor – American Superconductor
– is doing so as part of a broader effort to introduce high-temperature
superconducting technology into the electrical power industry.
The superconducting synchronous motor is less mature technologically than the
permanent magnet motor. Most sources argue (or do not contest) that it cannot be
matured quickly enough to be installed at acceptable risk on the first DD-21.
Advocates of the superconducting synchronous motor, while not necessarily
disagreeing with the Navy about whether the technology would be ready for
installation the first DD-21, argue that the technology for this kind of motor has
progressed in recent years more than others might realize and that the time needed to
mature the technology may be less than others estimate.
One technical issue regarding the superconducting synchronous motor concerned
the cost, reliability, and survivability of its cryogenic systems. Supporters argue that
this issue has effectively been resolved through the advent of high-temperature
superconducting materials (as opposed to older, lower-temperature superconducting
materials) and improved cryocoolers (refrigerator-like devices) that have made it
possible to achieve the necessary amount of cooling without the need for using
expensive liquid-helium cooling systems.
Some sources for this report raised a second issue – the possibility that the
superconducting wire in these motors might degrade over long periods of motor use.
In response, supporters of superconducting motors argue that superconducting wire
has been extensively tested and that its durability is now being proven in the
commercial electrical power industry.63
The question is how quickly a superconducting synchronous motor might be
made ready for use, how this would depend on the cost and intensity of the
development effort that is undertaken, and how the technology might consequently
fit into a longer-range strategy for incorporating electric-drive technology into Navy
ships. The Navy has initiated a program to build and test a 1,000-horsepower proof-
of-concept superconducting synchronous motor. According to American
Superconductor, such a motor can be built and tested by 2004. Upon completion of
this effort, the company says, a full-scale, 25,000-horsepower version could be
developed and completed by 2009, making it possible to have the motor enter service
with the fleet in 2012 – two years after the first DD-21 is scheduled to enter service,
and about the time that the first follow-on DD-21s would enter service. American
Superconductor says this estimated 10-year motor-development effort would cost a
total of about $90 million.
62(...continued)
Symposium on Electric Machines, Annapolis, MD, October 26-29, 1998; Mulholland,
Maxwell, and Stuart Karon. Letter to the editor, U.S. Naval Institute Proceedings, February
2000: 20, 22.
63 For articles on the use of superconducting wire in the commercial electrical power
industry, see Browne, Malcolm W. Power Line Makes Use of a Miracle of Physics. New
York Times, November 3, 1998; and Spotts, Peter N. Electric Power Cables That Just Can’t
Resist. Christian Science Monitor, November 5, 1998.

CRS-52
Superconducting Homopolar Motor.64 The homopolar motor, like the
superconducting synchronous motor, uses superconducting technology to achieve
stronger magnetic fields than non-superconducting motors. As a result, supporters
argue, this motor can be made more power-dense, quieter, and energy-efficient than
a permanent magnet motor. In addition, supporters argue, because the motor
employs DC current, rather than the AC current used by all the other motor types
discussed here, the homopolar motor permits the motor drive to be less complex and
thus less expensive than the motor drives associated with the other motor types.65
Because of its potential advantages, the Navy worked on developing the
homopolar motor for many years starting in the mid-1970s. This effort has been
continued in more recent years by General Atomics.
The homopolar motor, like the superconducting synchronous motor, is less
mature technologically than the permanent magnet motor. In addition to the issue of
the cryogenic system discussed above in connection with the superconducting
synchronous motor, the homopolar motor poses a second development issue
concerning the current collectors that transmit electrical power from the stationary
parts of the motor to the rotating parts. Supporters of the homopolar motor state that
solid-metal current collectors have been developed that are superior to the older
liquid-metal current collector technology previously used in homopolar motors, and
that this development risk has consequently already been substantially reduced.
Others point out that these new solid-metal collectors have been tested only at smaller
scales and need to proceed through larger-scale testing.
A third technical issue concerning homopolar motors concerns the need to
transfer low-voltage, high-current electrical power – the kind used by homopolar
motors – from the generator to the motor, and the implications that this would have
for the design of the electric-drive system. Work on this issue is progressing,
particularly in devising new designs for the motor that reduce the amount of low-
voltage current needed to operate the motor, but these developments have not yet
been tested at larger scales.
General Atomics believes that a quarter-scale (approximately 6,000-horsepower)
homopolar motor can be built and demonstrated at sea in about two and one-half
years at a cost of about $15 million. This motor, supporters argue, could be tested
on the quarter-scale LSV 2 submarine technology test vehicle. Designing, building
and testing a full-scale (i.e., 40,000 horsepower) homopolar motor, the company says,
would require additional time – perhaps another 2 or 3 years – and another $100
million or so.
64 The term homopolar (i.e., unipolar) refers to the fact that this motor uses direct current
(rather than alternating current) electricity and does not require either a reversal of current or
electrical commutation. As a result, the magnetic field and the electrical current in the
armature of a homopolar motor are constant over time and space (i.e., unvarying).
65 For a general discussion of the potential advantages of the homopolar motor and recent
developments in homopolar motor technology, see Walters, J.D., et al. Reexamination of
Superconductive Homopolar Motors for Propulsion. Naval Engineers Journal, January
1998: 107-116.

CRS-53
The Navy’s March 1999 report to Congress on electric-drive technology,
particularly its summary table, can be read to suggest that superconducting motors are
of limited near-term relevance to the U.S. Navy’s electric-drive technology program
because of their less-mature status. Such an interpretation, which the authors of the
report may not have intended, may be too dismissive of superconducting motor
technology. Although superconducting motor technology appears likely to take
longer to mature than permanent magnet technology, it might, if pursued, prove
suitable for use in a common electric-drive system for use on Navy surface ships and
submarines. The potential advantages of superconducting motors, combined with
their least-mature status among the motor technologies discussed here, raises the issue
discussed earlier of electric-drive technology posing longer- as well as shorter-term
issues for policymakers, and of the potential need for a technology development
roadmap stretching several years into the future.
Two Additional Comments. In discussing the issue of motor types, several
sources offered two points that put the motor issue into additional perspective. First,
they stated that the debate on motor types has led many discussions of electric-drive
technology for the U.S. Navy to become excessively focused on the merits of
competing motor designs as opposed to the more fundamental issue of the relative
merits of mechanical- vs. electric-drive technology.
Second, they argued that an excessive focus on the merits of various motor types
can obscure the issue that the motor is simply one component of an electric-drive
system that contains several other major components as well. A motor that might
seem the best when viewed in isolation might not lead to the best overall electric-drive
system because of its effects on other elements of the system design. The goal, they
point out, is to identify the best overall electric-drive system, not simply the best
motor.
Other (Non-Motor) Components. Information provided by sources to this
report indicates that there is considerable potential for evolution and improvement in
the non-motor elements of electric-drive technology. This is potentially significant,
because with the partial exception of the motor drive, there has been relatively little
discussion of how these other components could or should evolve or be improved.
Some sources suggested, for example, that developing newer and more compact
(i.e., lightweight) generators would reduce total system weight and space
requirements and make it easier to locate a surface ship’s gas turbine engines and
generators higher in the ship, thus reducing the amount of internal ship volume
occupied by the gas turbines’ large air intakes and exhaust ducts – one of the potential
architectural advantages of electric drive.66
Similarly, there may be potential for developing motor controllers even more
compact than the pulse-width modulated controllers now being developed. The ship-
wide power electrical distribution system can evolve and change in terms of key
66 For a discussion of advanced (permanent-magnet) generators for submarines, see
Hollung, Achim. PM Generators for Submarines. Naval Forces, Special Issue No. 2, 1999
(Conference Proceedings, Subcon ‘99, German Submarine Technology): 40-43.

CRS-54
characteristics such as of the type of current (AC or DC) and the voltage or voltages
employed. And as mentioned earlier, electric drive makes it possible to evolve the
propeller/stern configuration from the traditional arrangement (a horizontal shaft with
a propeller at the end) to a more advanced arrangement.
The potential to evolve and improve the other components of an electric-drive
system poses potential issues for Congress, including the following:
! How do these other components affect the overall cost-effectiveness of an
electric-drive system?
! Have sufficient attention and resources been directed to the development of
these other components?
! How should the potential for evolving these other components be factored into
the design of the baseline electric-drive system for the DD-21?
Application of Electric Drive to Specific Ship-Acquisition Programs
DD-21 Land-Attack Destroyers.67 Given the Navy’s January 2000
announcement that DD-21 class ships will be equipped with an electric-drive system,
a key follow-on issue for the program – and for the Navy’s overall electric-drive effort
– is what kind of electric-drive system the ship should employ. This issue is highly
significant, because the choice of system type would likely amount to a decision as to
which firms would be involved in building the system. Given the possibility that the
DD-21's system might become the basis for a common electric-drive system for the
Navy, the economic stakes for competing firms are potentially very high.68
The Navy’s acquisition strategy for the DD-21 program gives the two industry
teams that are competing for the right to design the DD-2169 wide latitude in
determining the features of their proposed DD-21 designs, including the type of
electric-drive system they will use. This approach is consistent with Navy and
Department of Defense acquisition reform efforts.
The potential for the DD-21's electric-drive system to become the basis of a
common electric-drive system, together with the Navy’s acquisition strategy for the
program, raises several potential issues for Congress, including the following:
67 For an earlier discussion of the application of electric drive and related technologies
to the design of a next-generation surface combatant with a full-load displacement of about
6,000 tons,, see Levedahl, William J. A Capable, Affordable 21st Century Destroyer. Naval
Engineers Journal, May 1993: 213-223.
68 For a discussion, see Costa, Keith J. Work on DD-21 Might Give Electric Boat An
Edge In Electric Drive Effort. Inside the Navy, August 13, 1998: 1, 4-6.
69 These are the Blue team, which is led by General Dynamics’ Bath Iron Works division
and also includes, among other firms, Lockheed Martin as the combat system integrator, and
the Gold Team, which is led by Litton Industries’ Ingalls Shipbuilding and includes, among
other firms, Raytheon as the combat system integrator.

CRS-55
! Procurement Schedule and Risk. Does the Navy’s new plan for procuring
the first DD-21 in FY2005 provide more than enough, not enough, or about
the right amount of time for developing an electric-drive system for the first
DD-21? How does the schedule for procuring the first ship affect the risk
associated with incorporating electric drive into the ship, or the potential cost-
effectiveness of the system that is developed?
! Funding for Development. Has the Navy provided adequate funding in its
overall DD-21 development program for development of the ship’s electric-
drive system? How is the amount of risk associated with developing electric-
drive technology affected by the amount of development funding?
! DD-21 Procurement Cost Goal. Is the Navy’s unit procurement cost goal
for the DD-21 – $750 million in FY1996 dollars for the fifth ship built at each
of the two shipyards that will build the ship – compatible with the objective of
equipping the DD-21 with an electric-drive system? If equipping the DD-21
with the most cost-effective electric-drive system would result in a ship design
that would cost more than $750 million in FY1996 dollars, should this
situation be resolved by increasing the $750 million procurement cost goal, by
reducing the procurement cost of the ship’s propulsion system, or by reducing
the procurement cost of other parts of the ship? If the procurement cost of the
propulsion system is reduced, how much less cost-effective would the resulting
propulsion system be, and what effects might this have for the idea of using the
DD-21 electric-drive system as the basis for a common system for the fleet?
! System Evolution. Given the potential for electric-drive technology to evolve
and improve over time, should the DD-21 be designed so that parts of the
system can be changed over time, either in the construction process (i.e.,
forward fitting for later ships in the program) or during life-cycle overhaul and
modernization (i.e., backfitting for earlier ships in the program)? What effect
might this have on the time and funding needed to develop the DD-21's
electric-drive system? Does the Navy’s acquisition strategy adequately address
this issue?
! Latitude for Competing Dd-21 Industry Teams. Does the Navy’s
acquisition strategy give the two competing DD-21 industry teams too much,
not enough, or about the right amount of latitude in determining the features
of the DD-21 electric drive system?
! Potential for Common Fleet-Wide System. Has the Navy structured the
DD-21 competition to take into account the possibility that the DD-21 electric-
drive system might become the basis for a common system for use by other
Navy surface ships and submarines? Does the DD-21 competition require the
two competing industry teams to select an electric drive system that would be
suitable for a wide array of Navy ships? Do the electric-drive technologies
being considered by the two industry teams include all those that might
contribute to an optimal common Navy electric-drive system? If not, what
effect might this have on the Navy’s downstream ability to achieve the most
cost-effective application of electric-drive on a fleet-wide basis? If there is a
conflict between optimizing the DD-21 electric-drive system and optimizing

CRS-56
a common electric-drive system for the fleet, how should the Navy resolve the
issue?70
If it is decided early in the DD-21 development effort that the DD-21 electric-
drive system will definitely become the basis for a common electric-drive system for
Navy surface ships and submarines, then there are grounds for arguing that the DD-21
acquisition process should be structured so that consideration is given to optimizing
the cost-effectiveness of electric-drive technology for the fleet, even if this adds costs
to the DD-21 program or results in an electric-drive system that is not fully optimized
for the DD-21 itself. If, however, it remains uncertain during the DD-21 development
effort whether the DD-21 system will form the basis for a common system,
policymakers may face a difficult decision in weighing the certain benefits of
optimizing the cost-effectiveness of the electric-drive system for the DD-21 against
the uncertain benefits of optimizing it for potential wider use in the fleet.
Given the competing motor technologies now being pursued, there are numerous
potential strategies that can be pursued concerning the type of motor used in the DD-
21 electric-drive system. The table below shows a variety of notional alternatives, but
is not an exhaustive list.
70 Questions regarding the relationship between the DD-21 electric-drive system and
potential electric-drive systems for U.S. submarines were raised by Representatives Herb
Bateman and Duncan Hunter at a June 27, 2000 hearing on submarine force stucture and
modernization issues held by the Military Procurement Subcommittee of the House Armed
Services Committee. For a discussion, see Bohmfalk, Christian. First Electric Drive
Submarine Not to Arrive in Fleet Until 2015. Inside the Navy, July 3, 2000. Representative
Bateman posed questions on this issue in an April 6, 2000 letter to the Secretary of the Navy.
For the text of this letter, see Text: Bateman Letter On Electric Drive. Inside the Navy, July
3, 2000.

CRS-57
Table 4. Selected Notional Options for Electric-Drive
System on Dd-21 Class Ships, by Motor Type
First Ship/Earlier Ships in Program
Later Ships in Program
Forward fit during
Backfit during
Forward fit
construction
later overhaul
during
construction
Induction
none
Induction
Induction
none
Permanent magnet
Induction
Permanent magnet
Permanent magnet
Induction
none
Superconducting
Induction
Superconducting
Superconducting
Permanent magnet
none
Permanent magnet
Permanent magnet
none
Superconducting
Permanent magnet
Superconducting
Superconducting
Sources differed regarding the amount of technical risk associated with
incorporating different versions of an electric-drive system into the first DD-21. The
lowest-risk option would appear to be a system using an induction motor connected
by a traditional horizontal shaft at the stern of the ship to a fixed-pitch propeller.
Although the Navy does not consider the induction motor suitable for use on
submarines, other components of this system could possibly form the basis for a
common electric-drive system for the fleet.
This option could be pursued as part of a longer-term acquisition and
modernization strategy for the DD-21 class in which later ships are built (and earlier
ships are possibly backfitted with) a permanent magnet or superconducting motor.
The potential cost-effectiveness of such an approach would depend on how it would
alter costs and capabilities for both DD-21 class ships and (if the system forms the
basis of a common fleet-wide system), subsequent classes of electric-drive-equipped
ships.
With some amount of added risk – how much is not certain, but not necessarily
enough to make the DD-21 program a high-risk effort – the lead ship’s system could
include a permanent magnet motor rather than an induction motor. This option could
lead to a streamlined approach for achieving a common electric-drive system under
which all Navy electric-drive systems use an permanent magnet motor. In assessing
this approach, policymakers would need to balance the risk associated with equipping
the first DD-21 with a permanent magnet motor against the savings associated with
developing, procuring, and supporting only one type of motor for both the DD-21
program and other classes of ships.

CRS-58
Although many sources agreed that there may not be enough time to develop an
advanced propeller/stern configuration for the first DD-21 such as a podded propeller,
they also agree that such a system could be developed within a few years and would
offer both cost and capability advantages for the DD-21. This raises the issue of
whether the baseline DD-21 design should be developed so as to facilitate the later
incorporation of a more advanced propeller/stern configuration.
On June 14, 2000, Ingalls Shipbuilding – a division of Litton Industries and the
leader of one of the two industry teams competing for the DD-21 – announced that
it had selected the NNS-led electric drive industry team for the preliminary design of
an electric drive propulsion system and will incorporate the NNS-led team’s
permanent magnet motor design into its initial system design proposal for the DD-
21.71
Virginia (SSN-774) Class Submarines. Electric-drive technology in some
form could be installed on follow-on Virginia-class submarines, potentially on a boat
procured within the next several years, depending on the configuration of the electric-
drive system and the intensity of the Navy’s development effort.72 Navy officials
testified in June 2000 that a nearer-term electric-drive system could be ready for a
Virginia-class boat procured in FY2010.73 Some industry sources suggested that it
could be ready for a boat procured in FY2007 if a decision were made in the near
term to pursue the option and adequate development funding was provided.
Given electric drive’s potential for achieving a substantial improvement in
submarine quieting, a key question for policymakers concerns the urgency of
achieving such an improvement: In light of current and projected antisubmarine
warfare capabilities of potential adversaries, how quickly might such an improvement
need to be incorporated into the U.S. submarine fleet?
71 Source: Litton Industries press release, June 14, 2000, entitled DD 21 Gold Team
Selects Newport News Team for Permanent Magnet Motor Development. The Ingalls-led
DD-21 team is known as the Gold Team. The press release stated: “The selection of the
Newport News team’s PMM [permanent magnet motor] design is a result of the Gold Team’s
independent, three-month evaluation of competing Permanent Magnet Motor proposals. Many
factors including acquisition cost, life cycle cost, maintenance, manning, efficiency, [and] risk
were analyzed and compared between the two motors. The final selection was accomplished
by using a systems engineering process, as required by the DD 212 contract.”
72 For earlier discussions of the application of electric drive to attack submarines about
the size of the Virginia class design, see Dade, Thomas B. Advanced Electric Propulsion,
Power Generation, and Power Distribution. Naval Engineers Journal, March 1994: 83-92,
and Dutton, Jeffrey L. Contrarotating Electric Drive for Attack Submarines. Naval
Engineers Journal, March 1994: 45-50.
73 Spoken testimony of Rear Admiral J. P. Davis and Rear Admiral Malcolm I. Fages
to the Military Procurement Subcommittee of the House Armed Services Committee at a
hearing on submarine force structure and modernization issues on June 27, 2000. For a
discussion, see First Electric Drive Submarine Not to Arrive in Fleet Until 2015, op cit, and
Bender, Bryan. US Navy Sets Sights on Electric Attack Submarine. Jane’s Defence Weekly,
July 26, 2000.

CRS-59
In addition to a major improvement in quieting, some industry sources have
suggested, and the Navy did not disagree, that electric-drive technology for
submarines, if pursued ambitiously, has the potential for altering the stern of a
Virginia-class submarine in a way that could reduce the procurement cost of the
submarine (currently $1.9 billion to $2.0 billion) by as much as $100 million. This is
highly significant, because the Navy is seeking to increase the Virginia-class
procurement rate in a few years from the currently planned rate of 1 per year to 2 or
more per year, and any actions to reduce the procurement cost of the Virginia-class
would make such an increase more affordable.
If the $100-million figure above is roughly correct, electric-drive technology
would represent a rare if not unique opportunity to make a change in the design of the
submarine that reduces its procurement costs by such a large amount without
reducing ship capability. Indeed, in more than a decade of searching for options for
reducing submarine procurement costs, CRS has encountered no other single design
change for a nuclear-powered submarine that could reduce procurement costs by such
a large amount without reducing ship capability. Although numerous design changes
have been suggested for the Virginia-class design (many of which have been or will
be implemented), most will reduce the cost of the Virginia-class design by much
smaller amounts (typically a few or several million dollars).
Pursuing electric-drive technology for submarines this ambitiously, however,
would be very expensive: It could easily require hundreds of millions of dollars, or
even more than a billion dollars, in research and development funding beyond the
funding that the Navy has already programmed for development of electric-drive
technology. As a consequence, even if the program succeeded in reducing the
procurement cost of the Virginia-class design by $100 million, it could be several
years before savings in Virginia-class procurement costs fully recouped the up-front
research and development costs of this development option. If the reduction in unit
procurement cost turned out to be something smaller – for example, $50 million
instead of $100 million – then the break-even point would be even farther in the
future. Even if the break-even point were not reached until the procurement of the
final units in the Virginia class, however, the technology would continue to act as a
source of recurring savings on submarines procured following completion of Virginia-
class procurement.
TADC(X) Auxiliary Dry Cargo Ships. Although often overlooked in
discussions of electric-drive technology, the Navy’s planned TADC(X) class of
auxiliary dry cargo ships, the first of which was procured in FY2000, is a near-term
candidate for electric-drive propulsion. The Navy states: “The [TADC(X)’s]
propulsion plant will either be diesel [with mechanical drive], gas turbine [with
mechanical drive], or electric drive.”74
74 U.S. Navy Internet page, “ADC(X) Baseline Design,” version as of April 20, 2000,
available at { http:/www.navsea.navy.mil/adcx/view/adcxbl.html }.

CRS-60
As a large, slower-speed (20- to 26-knot),75 non-combat ship now in
procurement that is somewhat similar to a commercial cargo ship, it might be feasible
and cost-effective to equip the TADC(X) with a currently-available European
commercial electric-drive system similar to those now being used for cruise ships –
a system employing a synchronous motor and possibly a podded propeller. This
would raise at least two potential issues for policymakers:
! Would equipping the TADC(X) with a commercial electric drive system using
a synchronous motor contribute to or detract from an effort to optimize the
application of electric-drive technology to Navy ships?
! Should the TADC(X) be equipped with a European electric-drive system if
that is the only kind of electric-drive system now available for the TADC(X)?
Jcc(x) Joint Command and Control Ships. Electric drive might similarly be
a candidate for the four Joint Command and Control (JCC[X]) ships that the Navy
plans to begin procuring in FY2004. The design of the JCC(X) has yet to be
determined, but one possibility being considered is to build them to modified
commercial-ship standards. If so, the JCC(X), like the TADC(X), might be a
candidate for a commercial electric-drive system.
The operational requirements of the JCC(X), however, might require an electric-
drive system with better quieting and shock resistance than a commercial system, in
which case the ship might be a candidate for a more advanced military electric-drive
system. If so, in light of the currently planned FY2004 date for procuring the first
JCC(X), one possibility might be to equip this ship with a version of the electric-drive
system that is developed for the DD-21. The question is whether the FY2004
procurement date for the first JCC(X) – one year earlier than the procurement date
for the first DD-21 – would permit this.
LHA Replacement Ships. LHD-8, the first of the five LHA replacement ships,
is to be built to a modified version of the basic Wasp (LHD-1) class design. The
modifications include, among other things, the use of a hybrid propulsion plant
consisting of a low-power electric-drive system for low-speed operations and a
mechanical-drive system for higher-speed operations. The low-power electric-drive
system will employ 1,000-horsepower electric motors using electricity produced by
the same diesel generators that produce electrical power for the rest of the ship. The
mechanical-drive system will be powered gas turbine engines (rather than the oil-fired
steam turbines used on LHDs -1 through -7). During low-speed operations, the
RPMs produced by the ship’s electric motors will be transmitted to the propellers
through the reduction gears of the ship’s mechanical-drive system.76 This hybrid
75 The Navy’s notional performance characteristics for the TADC(X) call for a
maximum sustained speed of 20 to 26 knots. (U.S. Navy Internet page, “ADC(X) Baseline
Design,” op cit.) A speed of 20 knots would be comparable to the maximum sustained speeds
of the ammunition and refrigerated stores ships that the TADC(X) is to replace.
76 Source: Information provided to CRS via telephone by Ingalls Shipbuilding, the
builder of LHD-1 class ships, July 24, 2000.

CRS-61
propulsion system is similar in some respects to the previously described diesel-
electric/gas turbine-mechanical system used on Britain’s Type 23 frigates.77
The Navy is now assessing whether the second through fifth LHA replacement
ships should be additional (and further-modified) LHD-1 class ships or a new-design
amphibious assault ship known as the LHX. The further-modified-LHD option might,
and the LHX option more certainly could, include a full electric-drive system.
In the case of the further-modified-LHD option, the issue for policymakers is
how the benefits of incorporating full electric drive into some of the LHDs, if feasible,
would compare to the costs of maintaining a fleet of LHDs with at least three kinds
of propulsion systems (steam turbine/mechanical drive for LHDs -1 through -7, hybrid
diesel/electric and gas turbine/mechanical drive for LHD-8, and gas turbine/electric
drive for subsequent LHDs).
CVN(X) Aircraft Carrier. The Navy’s March 1999 report to Congress on
electric drive states that while electric drive is feasible for future aircraft carriers,
mechanical drive would be more appropriate at this time – meaning that mechanical
drive would be more appropriate for CVN(X)-1, the first of the Navy’s planned class
of next-generation aircraft carriers, which is to be procured in FY2006. The Navy
report stated:
For a ship the size of an aircraft carrier, electric drive did not offer space or weight
savings over a steam driven mechanical drive design with appropriately sized
turbine generators. In addition, the studies found that the most affordable method
to achieve the objective of increased electric generating capacity was to use
mechanical drive with larger turbine generators.78
The Navy’s conclusion contrasts with a 1997 Naval Research Advisory
Committee (NRAC) report on the CVN(X) that strongly endorsed the idea equipping
the CVN(X) with electric-drive technology.79 Although the Navy’s March 1999
report reflects two years of additional information and study of the issue, in light of
the 1997 NRAC study and the potential for electric-drive technology to evolve and
improve, policymakers may review the Navy’s 1999 conclusion periodically (e.g.,
with the procurement of each carrier) to determine whether it remains valid.
77 See the background section for the description of the Type 23 propulsion system.
78 This passage is taken from the executive summary of the Navy’s report, which is
printed in its entirety in the background section of this report.
79 Naval Research Advisory Committee. CVX Flexibility. Washington, 1997. 80 p.
(Report to Assistant Secretary of the Navy (Research, Development and Acquisition), NRAC
97-1, October 1997.) The conclusions of the NRAC report on this point are also referenced
in Davis, Jacquelyn K. CVX, A Smart Carrier for a New Era. Washington and London,
Brassey’s, 1998. (A publication of The Institute for Foreign Policy Analysis, Inc., in
association with the Fletcher School of Law and Diplomacy, Tufts University) p. 45, 58, and
in Walters, J.D., et al. Reexamination of Superconductive Homopolar Motors for Propulsion.
Naval Engineers Journal, January 1998: 107-116.

CRS-62
Coast Guard Deepwater Cutters. The Coast Guard commissioned two
studies, both delivered in 1998, that examined various propulsion options, including
electric drive, for cutters procured under the Deepwater project. These reports,
however, did not come to any firm conclusions or recommendations regarding the
kind of propulsion system that might be best suited for this ship.80
In 1998, the Navy and the Coast Guard issued a joint policy statement setting
forth a new “national fleet concept” under which the two services would seek to
coordinate their activities more closely in various areas, including equipment
procurement. The document states:
As we enter the next millennium... the Navy and Coast Guard, together, must
deploy forces with greater flexibility, adaptability and affordability....
Because of incompatible equipment, mutual logistics support has proven difficult,
as has the ability to exchange near real-time intelligence and information. As
partners in maritime security, our approach should stress commonality wherever
appropriate, from shipboard propulsion systems to aircraft components to
training standards.
The National Fleet has two main attributes. First, the fleet is comprised of
surface combatants and major cutters that are affordable, adaptable, interoperable,
and with complementary capabilities. Second, whenever appropriate, the fleet is
designed around common equipment and systems, and includes coordinated
operational planning, training and logistics....
The Navy and Coast Guard will work together to build a National Fleet of
multi-mission surface combatants and cutters to maximize our effectiveness across
all naval and maritime missions. The Navy and Coast Guard will coordinate
surface ship planning, information systems integration, and research and
development, as well as expand joint concepts of operations, logistics, training,
exercises and deployments. The Coast Guard and Navy will work together to
80 Krull, R. D. Propulsion Systems Survey for the USCG Deepwater Surface Platform.
Stevensville (MD), 1998. 23 p. (Report No. CG-D-13-98, Final Report, February 1998,
Prepared for U.S. Department of Transportation, United States Coast Guard, Acquisition (G-
A), and U.S. Coast Guard Research and Development Center, available to the U.S. public
through the National Technical Information Service, Springfield, Virginia); Krull, R. D., and
H,. Robey. Integrated Electric Drive Application to USCG Deepwater Project. Stevensville
(MD)?, 1998, 13 p. (Prepared for U.S. Coast Guard Research and Development Center,
Groton, CT, 21 August 1998, Contract No. DTCG39-94-D-E56616, Delivery Order
DTCG39-97-F-E00348) The first report provides an overview of various potential prime
movers, transmission systems (including electric drive), and propellers and other propulsors.
The report states that “a number of currently operating propulsion system concepts that would
be new to the Coast Guard, such as water jets, podded propulsors, and AC electric drives[,]
are candidate technologies.” The report also notes the potential advantages of various options
(including electric drive) for meeting certain mission requirements of a Deepwater cutter. The
second report provides a general discussion of electric drive and potential advantages and
disadvantages, and a description of the Navy’s IPS program.

CRS-63
acquire and maintain future ships that mutually support and complement each
service's roles and missions.81
The national fleet concept, with its emphasis on commonality, raises a potential
issue for policymakers concerning the possibility of using electric-drive on the cutters
that are to be procured under the Deepwater project. Equipping these cutters with
electric-drive could produce ship capability and life-cycle cost benefits for the Coast
Guard similar to those that electric-drive technology will produce for the Navy,82 and
potentially improve economies of scale for both the Navy and Coast Guard in the
production, operation, and life-cycle support of ship propulsion systems.
In assessing the feasibility of this notion, one issue to address would be the size
of the cutters’ propulsion plant. The cutters to be procured under the Deepwater
project will likely be much smaller than the DD-21 design. The cutter might have a
full load displacement of less than 5,000 tons, while the DD-21 might have a
displacement of about 12,000 tons. It is not clear that an electric-drive system
designed for the DD-21 or other large Navy ships could be easily scaled down or
otherwise modified to produce a system suitable for a cutter-sized ship. If the Navy’s
electric-drive system employs a modular architecture in which smaller modules are
combined to create a system with the requisite power, scaling the system down to a
size appropriate for a Coast Guard cutter might be made easier. If some elements of
the system needed to be changed to make the system suitable for a cutter,
policymakers would face an issue of whether the design and development costs for
the changed components should be paid for by the Coast Guard, the Navy, or some
combination.
A second issue concerns the schedule for the Deepwater program. Under the
Coast Guard’s plans, the first Deepwater cutter is to be procured in 2002 – three
years before the DD-21. The three industry teams now competing for the Deepwater
project, moreover, have completed much of the initial work on their proposed
Deepwater cutter designs. Incorporating electric-drive into the first Deepwater
cutters might thus require restructuring the Deepwater program to delay the start of
cutter procurement and have the industry teams redo much of their initial design
work.
This would delay the introduction of the new cutters into the Coast Guard’s fleet
– something the Coast Guard strongly wants to avoid, given the advanced age, limited
capabilities, and high operating costs of its current cutters. It would also increase
research and development costs for the Deepwater project – something the Coast
Guard also strongly wants to avoid, given the Coast Guard’s limited acquisition
budget and an already-significant challenge in identifying adequate funding for the
Deepwater project as currently conceived.
81 NATIONAL FLEET — A Joint Navy/Coast Guard Policy Statement. Washington,
1998. (September 21, 1998) 2 p. Emphasis added.
82 The 1998 NATO report that endorsed electric drive as feasible and viable focused on
a notional design for a 4,000-ton frigate – a ship potentially about the same size as the
Deepwater cutter.

CRS-64
Another approach would be to build the first few Deepwater cutters as
mechanical-drive ships, then build later cutters to a modified design that incorporates
electric drive. This would resolve the issue concerning the Coast Guard’s desire to
begin procuring cutters in 2002, but would still leave the issue of who should pay for
any design and development work that would be needed to modify the Navy’s
electric-drive system to make it suitable for use in the Coast Guard’s new cutters.
In addition, given the potential impact of electric drive on the overall design of
a ship, the amount of ship redesign needed to optimize the application of electric drive
to later ships in the program could be extensive – and thus expensive. Redesigned
ships might also be delivered later, slowing the pace at which new cutters are
introduced into Coast Guard service. The alternative of simply incorporating electric
drive into a baseline Deepwater cutter originally designed for mechanical drive would
likely result in a ship that does not achieve the full benefits of electric drive.
Building later ships in the production run with electric drive would also create
an issue regarding a lack of propulsion-equipment commonality among the Coast
Guard’s new cutters. This would add complexity and possibly cost to the Coast
Guard’s strategy for life-cycle operation and support of the new cutters.
Another issue that may arise concerns the composition of the industry teams that
are competing for the Deepwater and DD-21 programs. The teams competing for
these two programs contain differing combinations of firms, which may make it
difficult to transfer electric-drive technology from the DD-21 program to the
Deepwater project without compromising “firewalls” that are intended to prevent
transmission of competition-sensitive information between teams competing for the
same program. In addition, one source suggested that the idea of incorporating
electric drive into the Deepwater cutters could itself add political uncertainty to the
Deepwater project, reducing industry confidence in the program.
Potential questions for policymakers include the following:
! How necessary is it to procure the first Deepwater cutter in 2002? If
procurement were delayed to 2005, how would this affect Coast Guard fleet
capabilities and operational costs? What would be the effect on the Deepwater
project?
! How do the potential ship-capability benefits of incorporating electric-drive
into Deepwater cutters compare with the benefits of incorporating it into a
Navy surface combatant like the DD-21?
! How do the potential savings of incorporating electric-drive technology into
the new cutters (from reduced life-cycle operating costs and commonality with
the Navy in the production, operation, and support of ship propulsion
equipment) compare with the potential additional costs of this option (for
design and development work, and potentially due to loss of commonality in
propulsion equipment across all the new cutters that are procured)?

CRS-65
! How significant a factor should the principles set forth in the Navy/Coast
Guard national fleet policy statement be in considering the issue of the new
cutters’ propulsion equipment?

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