Propulsion Systems for Navy Ships and Submarines
Gao ID: GAO-06-789R July 6, 2006In recent years, the Navy has used nuclear propulsion systems for its submarines and most aircraft carriers and conventional propulsion systems that rely on fossil fuel for its surface combatants and amphibious warfare ships. As the Navy looks to design an affordable force that is capable of meeting future security challenges, some of the assumptions and factors that have guided past Navy decisions on propulsion systems may require reassessment. For example, technological advances have enabled greater efficiency in both nuclear and conventional propulsion systems. Moreover, the cost of fossil fuel has risen sharply in recent years. Congress requested that we review the Navy's assessment of alternative propulsion methods for submarines and surface combatants. Our objectives were to determine (1) the status and scope of key Navy studies on alternative propulsion methods, (2) the major improvements to existing propulsion systems, (3) near-term and future ships' propulsion systems, and (4) the various ship propulsion related technologies the Navy is pursuing. In March 2006, we provided you with a briefing of our findings regarding propulsion systems for Navy ships and submarines. This report summarizes the results of that briefing as well as additional work we performed since that time.
The Navy has completed one study, and is in the process of completing two other studies on alternative propulsion systems for surface combatants, amphibious warfare ships, and submarines. The completed study is a "quick look" analysis of comparative life cycle costs of nuclear and fossil-fueled surface combatants and amphibious warfare ships. Although the study attempted to examine the fiscal break-even point for nuclear and conventional propulsion systems, it had several limitations. Specifically, it did not consider the operational requirements or advantages of nuclear and conventionally powered propulsion systems, nor did it undergo a high-level, Navy-wide review. According to Navy officials, the second study, required by the 2005 Chief of Naval Operations guidance, will be similar, but will provide in-depth analysis covering costs and operational factors for surface combatants as well as submarines. The Navy anticipates that the third study, required by the National Defense Authorization Act for Fiscal Year 2006, will build upon the Chief of Naval Operations study. Our limited review indicates that while the planned methodology for this study, as described by Navy officials, appears reasonable, its usefulness will depend on the extent to which the Navy uses accurate, reliable data and reasonable assumptions for its modeling and considers all relative costs. Nuclear and conventional propulsion systems for Navy ships and submarines have been improved in recent years. According to Navy officials, nuclear power plants are now simpler and smaller with reduced maintenance and personnel requirements, and their life span has also been increased. These reported improvements have eliminated the need for refueling newer submarines, such as the Virginia class submarines. Improvements have also been reportedly made to conventional propulsion systems, such as the Integrated Power System, which produces electrical power for both the propulsion system and ship's support systems. Ships being developed in the near term and long term will have a variety of newly designed propulsion systems depending on their size, mission, and ship characteristics. For example, the Littoral Combat Ship will have two diesel engines for low-speed operations, which will be augmented by two gas turbine engines for high-speed operations. The next-generation destroyer, DDG 1000, will have an Integrated Power System consisting of four gas turbines and two advanced induction motors, which will supply electrical power for the propulsion and ship support systems. The first aircraft carrier to be built under the CVN 21 program will have a newly designed nuclear power plant, and the Navy's amphibious replacement ship, LHA 6, will utilize a combined gas turbine and electric propulsion system instead of the steam propulsion systems now used in many amphibious warfare ships. The Navy spent over $212 million from fiscal years 2003 through 2005, and plans to invest an additional $264 million from fiscal years 2006 through 2011 to develop propulsion and ship support technologies designed to make future ships more fuel efficient and mission effective. These technologies, which are at various levels of maturity and not yet ready for implementation, focus on making electric motors smaller but more powerful, using high-speed generators without reduction gears, and using fuel cells. These technologies will still require fossil fuel as an energy source, but Navy officials stated they have the potential to reduce the amount of fossil fuel needed and improve ship operations.
GAO-06-789R, Propulsion Systems for Navy Ships and Submarines
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July 6, 2006:
The Honorable Roscoe G. Bartlett:
Chairman:
Subcommittee on Projection Forces:
Committee on Armed Services:
House of Representatives:
Subject: Propulsion Systems for Navy Ships and Submarines:
Dear Mr. Chairman:
In recent years, the Navy has used nuclear propulsion systems for its
submarines and most aircraft carriers and conventional propulsion
systems that rely on fossil fuel for its surface combatants and
amphibious warfare ships. As the Navy looks to design an affordable
force that is capable of meeting future security challenges, some of
the assumptions and factors that have guided past Navy decisions on
propulsion systems may require reassessment. For example, technological
advances have enabled greater efficiency in both nuclear and
conventional propulsion systems. Moreover, the cost of fossil fuel has
risen sharply in recent years.
You requested that we review the Navy's assessment of alternative
propulsion methods for submarines and surface combatants. Our
objectives were to determine (1) the status and scope of key Navy
studies on alternative propulsion methods, (2) the major improvements
to existing propulsion systems, (3) near-term and future ships'
propulsion systems, and (4) the various ship propulsion related
technologies the Navy is pursuing. In March 2006, we provided you with
a briefing of our findings regarding propulsion systems for Navy ships
and submarines. This report summarizes the results of that briefing as
well as additional work we performed since that time, and transmits the
briefing slides with the updated information. (See enc.) Because of
command changes at both the Naval Sea Systems Command and the Office of
the Chief of Naval Operations and other factors, the Navy has not
completed two ongoing studies. As a result, we were not able to assess
the results of these studies.
To determine the status and scope of the Navy studies on alternative
propulsion methods, the major improvements to existing propulsion
systems, and the various ship propulsion-related technologies the Navy
is pursuing, we reviewed and analyzed Navy and outside research
organizations' analyses and our prior report related to propulsion
systems for Navy ships and submarines. We also discussed propulsion
systems with officials from the Naval Sea Systems Command, the Office
of Naval Research, the Office of Naval Reactors, the Office of the
Chief of Naval Operations Surface Warfare Directorate, and the Defense
Advanced Research Projects Agency. We obtained and analyzed information
on Navy propulsion technologies from officials from the Naval Sea
Systems Command, the Office of Naval Reactors, the Office of Naval
Research, and the Office of the Chief of Naval Operations Surface
Warfare Directorate. We performed our work from December 2005 through
April 2006 in accordance with generally accepted government auditing
standards.
Summary:
The Navy has completed one study, and is in the process of completing
two other studies on alternative propulsion systems for surface
combatants, amphibious warfare ships, and submarines. The completed
study is a "quick look" analysis of comparative life cycle costs of
nuclear and fossil-fueled surface combatants and amphibious warfare
ships. Although the study attempted to examine the fiscal break-even
point for nuclear and conventional propulsion systems, it had several
limitations. Specifically, it did not consider the operational
requirements or advantages of nuclear and conventionally powered
propulsion systems, nor did it undergo a high-level, Navy-wide review.
According to Navy officials, the second study, required by the 2005
Chief of Naval Operations guidance, will be similar, but will provide
in-depth analysis covering costs and operational factors for surface
combatants as well as submarines. The Navy anticipates that the third
study, required by the National Defense Authorization Act for Fiscal
Year 2006,[Footnote 1] will build upon the Chief of Naval Operations
study. Our limited review indicates that while the planned methodology
for this study, as described by Navy officials, appears reasonable, its
usefulness will depend on the extent to which the Navy uses accurate,
reliable data and reasonable assumptions for its modeling and considers
all relative costs.
Nuclear and conventional propulsion systems for Navy ships and
submarines have been improved in recent years. According to Navy
officials, nuclear power plants are now simpler and smaller with
reduced maintenance and personnel requirements, and their life span has
also been increased. These reported improvements have eliminated the
need for refueling newer submarines, such as the Virginia class
submarines. Improvements have also been reportedly made to conventional
propulsion systems, such as the Integrated Power System, which produces
electrical power for both the propulsion system and ship's support
systems.
Ships being developed in the near term and long term will have a
variety of newly designed propulsion systems depending on their size,
mission, and ship characteristics. For example, the Littoral Combat
Ship will have two diesel engines for low-speed operations, which will
be augmented by two gas turbine engines for high-speed operations. The
next-generation destroyer, DDG 1000,[Footnote 2] will have an
Integrated Power System consisting of four gas turbines and two
advanced induction motors, which will supply electrical power for the
propulsion and ship support systems. The first aircraft carrier to be
built under the CVN 21 program will have a newly designed nuclear power
plant, and the Navy's amphibious replacement ship, LHA 6, will utilize
a combined gas turbine and electric propulsion system instead of the
steam propulsion systems now used in many amphibious warfare ships.
The Navy spent over $212 million from fiscal years 2003 through 2005,
and plans to invest an additional $264 million from fiscal years 2006
through 2011 to develop propulsion and ship support technologies
designed to make future ships more fuel efficient and mission
effective. These technologies, which are at various levels of maturity
and not yet ready for implementation, focus on making electric motors
smaller but more powerful, using high-speed generators without
reduction gears, and using fuel cells. These technologies will still
require fossil fuel as an energy source, but Navy officials stated they
have the potential to reduce the amount of fossil fuel needed and
improve ship operations.
Navy Has Completed One Study on Alternative Propulsion Systems and Has
Two Others in Progress:
The Navy has completed one study and is in the process of completing
two other studies of alternative propulsion methods for surface
combatants, amphibious warfare ships, and submarines. These studies are
(1) the 2005 "quick look" analysis of comparative costs of nuclear and
fossil-fueled surface ships, (2) the 2005 Chief of Naval Operations
guidance-directed study on alternative propulsion methods for surface
combatants and submarines, and (3) the National Defense Authorization
Act for Fiscal Year 2006-directed study on alternative propulsion
methods for surface combatants and amphibious warfare ships.
In the first study, the Office of Naval Reactors, which is responsible
for all aspects of the Navy's nuclear propulsion program and plants,
conducted a "quick look" analysis of comparative costs of nuclear and
fossil-fueled surface ships in 2005. The study attempted to determine
the fossil fuel price point at which it becomes advantageous to use
nuclear propulsion for amphibious warfare ships and surface combatants.
This analysis was based on a review of historical and projected fossil
fuel costs as well as the historical costs associated with nuclear
aircraft carriers and cruisers. However, Navy officials cautioned that
the study did not undergo a high-level Navy-wide review and contained
several limitations and assumptions. For example, the study did not
consider such factors as the operational advantages of nuclear and
conventionally powered propulsion systems, the mission requirements
under its Sea Power 21[Footnote 3] concept of operations, and costs
associated with lead ship design. The "quick-look" analysis indicated
that the breakeven points for a notional large deck amphibious warfare
ship (LHA/LHD) and a notional surface combatant are $80 and $205, per
barrel respectively. However, since this analysis contained several
limitations and assumptions, a more comprehensive analysis may yield
different results.
In addition to the "quick look" analysis, the 2005 Chief of Naval
Operations guidance directed the Naval Sea Systems Command to conduct a
study on alternative propulsion methods for submarines and surface
combatants. The objective of the 2005 Chief of Naval Operations-
directed study is to evaluate current propulsion systems, considering
the operational needs of Sea Power 21 and the cost and availability of
technology and energy sources. The 2005 Chief of Naval Operations
guidance directed the Naval Sea Systems Command to complete this study
by July 2005; however, at the time of our review, Naval Sea Systems
Command officials stated that because of command changes at both the
Naval Sea Systems Command and the Office of the Chief of Naval
Operations, the study would not be completed until May 2006.[Footnote
4] According to Navy officials, the Chief of Naval Operations-directed
study will use a more comprehensive model to evaluate fuel source and
propulsion plant alternatives for both submarines and surface
combatants than did the "quick look" study. It will analyze ship
design, using such factors as mission requirements; operational and
support costs; manpower requirements; and fuel consumption, costs, and
sources to determine at what price level the cost of diesel fuel (over
the life of the ship) equals the additional life cycle cost of a
similar ship powered by a nuclear propulsion plant.
The National Defense Authorization Act for Fiscal Year 2006 directed
the Navy to conduct an analysis and report on alternative propulsion
methods for amphibious warfare ships and surface combatants by November
1, 2006. Additionally, the conferees directed the Navy to brief the
congressional defense committees on the organization and study plan for
the preparation of the report by April 1, 2006.[Footnote 5] On April 6,
2006, the Subcommittee on Projection Forces, House Committee on Armed
Services, held a hearing at which the Navy testified on its plans to
conduct the study in order to fulfill the requirement for a briefing.
Navy officials stated that study guides will be developed for the
National Defense Authorization Act study, and the study will build upon
the methodology and results of the 2005 Chief of Naval Operations-
directed study. Specifically, the study will analyze alternative
propulsion systems in amphibious warfare ships, medium surface
combatants, and small surface combatants; evaluate cost versus
operational effectiveness; and compare nuclear plant with diesel fuel
marine[Footnote 6] plant alternatives. According to Navy officials, the
study will analyze conceptual ship design to estimate acquisition costs
and the life cycle costs of each variant. For each ship type, a break-
even cost analysis will be performed to determine the cost of crude oil
for which the life cycle cost of a nuclear propulsion variant of a ship
concept will equal the life cycle cost of a diesel fuel marine concept.
Navy officials said that the study will consider technologies such as
nuclear power, gas turbines, diesels, fuel cells, mechanical drive,
electrical drive, and various types of propellers, as well as other
innovative concepts.
Based on our limited analysis, the Navy's plans to conduct the National
Defense Authorization Act for Fiscal Year 2006-directed study, as
outlined in the Navy's statement for the hearing before the
Subcommittee on Projection Forces, House Committee on Armed Services,
appear reasonable for conducting a more thorough analysis on
alternative propulsion systems for surface combatants and amphibious
warfare ships. The methodology indicates that study guides will be
developed to guide the study and major assumptions will be identified
and documented. Additionally, the methodology will include
consideration of nuclear and fossil fuel power plants that will meet
mission requirements, and the use of modeling techniques to capture
appropriate costs and evaluate mission effectiveness of various
propulsion plant alternatives.
However, because the Navy had not completed its study guides for the
analysis at the time of our review, we could not independently verify
that they will be adequate to guide the study, nor could we determine
if all relative costs will be considered and other pertinent factors
addressed. For example, while the methodology indicated that manpower
costs will be considered, it did not indicate whether these costs will
include the additional training costs for nuclear-qualified personnel.
Our prior work on the cost-effectiveness of conventionally and nuclear-
powered carriers indicated that personnel training costs are
substantially higher for nuclear-qualified personnel.[Footnote 7] Our
prior work also documented that the support activities required for
nuclear-powered ships add significant costs. Additionally, it is highly
important that accurate, reliable data are used for all of the models
used to support the study. The consideration of all relative costs and
use of accurate, reliable data will determine the extent to which the
study results will be valid and useful.
Improvements Have Been Made to Conventional and Nuclear Propulsion
Systems:
The Navy has made improvements to both its nuclear and conventional
propulsion systems. According to Navy officials, nuclear power plants
are now simpler in design and smaller; have reduced maintenance
requirements; and require half the manpower of older plants, as
demonstrated by the design of the CVN 21 class aircraft carrier.
Officials also stated that the life of nuclear reactor cores has been
extended. For example, according to Navy officials, the extended life
span of reactor cores eliminates the need for refueling newer
submarines, which have a 33-year life span. This compares with the
earlier Los Angeles class submarines, which are usually refueled at the
18-to 20-year point in their service life.
Improvements have also been made to conventional propulsion systems.
Currently, conventionally powered ships have separate systems dedicated
to propulsion and ship support systems. An improvement upon this is the
Integrated Power System. According to Navy officials, the Integrated
Power System will enable conventional systems to produce electrical
power for both the propulsion system and ship's support systems.
Instead of the propeller drive shaft being connected to the engine
through reduction gears, the Integrated Power System enables the
propeller to be connected directly to an electric motor without the use
of reduction gears. Officials further stated that the Integrated Power
System will provide the electrical power for transformational weapons
systems on future ships, improve survivability by allowing rapid
reconfiguration of Power, and reduce acoustic signature or detection by
sonar. The design of the Integrated Power System will require fewer
components to the system, which, according to Navy officials, will
result in reduced maintenance requirements and life cycle costs.
Navy Ships in Development Will Have a Variety of Newly Designed
Propulsion Systems:
Navy officials stated that ship requirement factors, which are
developed during the early phases of ship design, drive the type of
propulsion system that is selected for a ship. Some factors that
influence the type of propulsion system selected are the maximum
sustained speed required, operating profile (a characterization of how
the ship will be used), acquisition cost constraints, industrial base
capabilities, and the maturity of any new technology being considered.
The ships planned for both near-term and future ship construction will
utilize a variety of newly designed propulsion systems. Navy officials
said that a new underway replenishment vessel, the T-AKE, will utilize
a diesel-electric propulsion system. Delivery of the first T-AKE ship
is expected in June 2006. Another type of ship, the Littoral Combat
Ship, is expected to have a hybrid propulsion system consisting of two
gas turbines, for high-speed use, and two diesel engines, for low-speed
use. According to Navy officials, the hybrid system of the Littoral
Combat Ship will enable efficient low-speed cruising. Delivery of the
first Littoral Combat Ship is expected in fiscal year 2007.
Additional future ship construction includes a next-generation
destroyer, DDG 1000; an amphibious replacement ship, LHA 6; a new CVN
21 class aircraft carrier; and a next-generation cruiser, CG(X).
According to Navy officials, DDG 1000 will have an Integrated Power
System consisting of four gas turbines and two advanced induction
motors. The amphibious replacement ship, LHA 6, will utilize a combined
gas turbine and electric propulsion system instead of the steam
propulsion systems used in many amphibious warfare ships. Delivery for
both DDG 1000 and LHA 6 is expected in fiscal year 2012. According to
Navy officials, the first aircraft carrier to be built under the CVN 21
program, CVN 78, will have a newly designed nuclear power plant,
allowing for a reduction in both manning and reactor plant components.
Delivery of CVN 78 is expected in fiscal year 2015. A propulsion
decision has not yet been made for CG(X), although, according to Navy
officials, CG(X) is likely to leverage the technology used in the DDG
1000 propulsion system, such as the Integrated Power System.
Navy Is Spending Some Research and Development Funds to Develop New
Propulsion Technologies:
In addition to analyzing alternative propulsion technologies for ships
currently in development, the Navy is also spending research and
development funds to develop new technologies to improve propulsion and
support systems. For fiscal years 2003 through 2005, the Navy spent
over $212 million and plans to spend an additional $264 million for
fiscal years 2006 through 2011 to conduct research for various
technologies, such as superconducting motors, fuel cells, and high-
speed generators. None of these technologies are immediately ready to
be implemented in ship designs. However, the Office of Naval Research,
which is responsible for managing advanced research, has categorized
the maturity of each technology being funded by technology readiness
levels 1 through 9. For example, a technology readiness level 1
indicates that the technology is still in a basic research phase, while
a technology readiness level 9 indicates that a technology has been
fully demonstrated. Some technologies being explored by the Navy,
including fuel cell technology, high-speed generators, and
superconducting motors, are at technology readiness levels 3 through 5.
Level 5 indicates that the technologies have advanced to the point
where stand-alone experiments can be conducted or the technology can be
integrated with other systems in the target environment. These
technologies will still require fossil fuel as an energy source, but
Navy officials stated that when and if they are implemented, they will
significantly reduce the amount of fuel required and improve ship
operations.
According to Office of Naval Research officials, improvements to
electrical components will generally improve fuel efficiency and
overall mission effectiveness of future Navy surface ships. For
example, superconducting motors, using special wiring to lower the
resistance of electricity flow and employing cryogenics to reduce
temperatures within the motor, will be more powerful and smaller,
thereby reducing weight and saving onboard space for other purposes.
High-speed generators, also projected to be smaller, will make it
possible to couple high-speed gas turbine engines directly to the
generators without the use of reduction gears, thereby reducing weight,
saving space, and making the engines more fuel efficient. Eliminating
these reduction gears will also help future ships to be quieter and
consequently more difficult to be detected by enemy forces. The Office
of Naval Research is also conducting research into fuel cell
technology. Germany recently produced two submarines with fuel cell
propulsion systems, but a Navy official said that nonnuclear submarines
do not meet the mission requirements of the United States Navy.
Additionally, these fuel cells use onboard hydrogen in its natural
state, which is difficult and dangerous to store in large quantities.
Conversely, the fuel cell technology the Office of Naval Research is
pursuing involves extracting hydrogen from diesel fuel, which can be
safely stored and transferred at sea, according to the official. The
hydrogen is used to produce electrical power without the use of diesel
or gas turbine engines. The use of fuel cells would also permit a
ship's power system to be dispersed throughout the ship, increasing the
ship's ability to survive if attacked, according to Navy officials.
Office of Naval Research officials stated that fuel cell technology is
promising for naval application and has already completed some
prototype testing. However, officials stated that the technology is at
least 3 to 5 years away from acquisition consideration.
Agency Comments:
We received technical comments from DOD, which we incorporated as
appropriate.
We are sending copies of this report to the Secretary of Defense and
other interested parties. We will provide copies of this report to
others upon request. In addition, the report is available at no charge
on the GAO Web site at [Hyperlink, http://www.gao.gov].
If you or your staff have any questions about this report, please
contact me at (202) 512-4402 or stlaurentj@gao.gov. Contact points for
our Offices of Congressional Relations and Public Affairs may be found
on the last page of this report. Key contributors to this report were
Patricia Lentini, Assistant Director, Willie Cheely, Elisha Matvay, and
George Morse.
Sincerely yours,
Signed by:
Janet A. St. Laurent:
Director, Defense Capabilities and Management:
Enclosure:
Status of Navy Analysis of Alternative Propulsion Systems:
Contents:
Background:
Status and Scope of Key Navy Studies of Alternative Propulsion Systems:
Major Improvements to Existing Propulsion Systems:
Likely Propulsion Systems for Near Term and Future Ship Construction:
Selected Technologies and Funding for Future Propulsion Systems:
Background:
This briefing is in response to your request that GAO review the Navy's
assessment of alternative propulsion methods for submarines and surface
combatants.
The committee expressed concerns about the assumptions and factors that
have guided past Navy decisions on propulsion systems and the global
demand and price of fossil fuel.
The Navy currently has nuclear powered submarines and aircraft
carriers, and conventionally powered surface combatants, amphibious
warfare ships and aircraft carriers.
Status and Scope of Key Navy Studies of Alternative Propulsion Systems:
The Nary has completed a "quick look" analysis of alternative
propulsion systems and has two other directed studies in process. These
include:
* The Naval Reactors "quick look" analysis presented to Congressman
Bartlett on October 1. 2005.
* Chief of Naval Operations (CNO) directed study estimated to be
completed by May 2006, but had not been approved by Navy leaders as of
June 14. 2006.
* National Defense Authorization Act for Fiscal Year 2006 directed
study to be completed by November 1, 2006.
Status and Scope of the Naval Reactors "Quick Look" Analysis:
*Naval Reactors officials conducted an analysis of comparative costs of
nuclear and fossil-fueled surface ships. This analysis:
* Was based on a "quick look" study of historical and projected fossil
fuel costs as well as the historical costs associated with nuclear
aircraft carriers and cruisers,
* Attempted to determine the fossil fuel price point at which it
becomes advantageous to use nuclear propulsion for amphibious warships
and surface combatants; and:
* Did not undergo Navy-wide review.
Naval Reactors officials stated that their analysis contained the
following limitations and assumptions:
* Did not consider the operational advantages of nuclear and
conventionally powered propulsion systems;
* Did not consider the mission requirements under Sea Power 21, the
Navy's current operational concept:
* Did not consider lead ship design and associated costs or design
constraints associated with different propulsion systems; and:
* Assumed a single nuclear propulsion plant for all ship classes
analyzed.
Status and Scope of the 2005 CNO Directed Study:
Naval Sea Systems Command (NAVSEA), in response to 2005 CNO Guidance,
commenced a study an alternative propulsion methods for submarines and
surface combatants.
The objective of the CNO directed study is to evaluate current
propulsion systems in light of operational needs of Sea Power 21,
taking into account cost and availability of technology and energy
sources.
CNO directed NAVSEA to complete this study by July 2005. NAVSEA
estimated that the study would not be completed in May 2006, as a
result of command changes at both NAVSEA and CNO. As of June 14, 2006,
the study had not been approved by Navy leaders.
The CNO directed study will use a more comprehensive model to evaluate
fuel source and propulsion plant alternatives for both submarines and
surface combatants.
It will analyze ship design, using such factors as mission
requirements; operational and support costs; manpower requirements; and
fuel consumption, costs, and sources, to determine at what price level
the cost of diesel fuel (over the life of the ship) equals the
additional life cycle cost of a similar ship powered by a nuclear
reactor.
NAVSEA has not developed guidelines or preliminary documents to further
define this CNO-directed study.
Status and Scope of National Defense Authorization Act Directed Study:
Section 130 of the National Defense Authorization Act for Fiscal Year
2006 subsequently directed the Navy to conduct an analysis on
alternative propulsion methods for amphibious warfare ships and surface
combatants by November 1, 2006,
Conferees expect the Navy to brief the congressional defense committees
on the organization and study plan for the preparation of this report
by April, 2006,
Major Improvements to Existing Propulsion Systems - Nuclear:
According to the Navy, nuclear power plants have been improved for
aircraft carriers and submarines which will result in lower life cycle
costs.
* Nuclear power plants are now simpler in design and smaller; have
reduced maintenance requirements; and require half the manpower of
older plants, as demonstrated by the design of the CVN 21 class
aircraft carrier.
* Naval Reactors officials stated that the life of nuclear reactor
cores has been extended. For example, the extended life span of reactor
cores eliminates the need for refueling for submarines, which have a 33-
year life span,
Major Improvements to Existing Propulsion Systems - Conventional:
Currently conventional ships have separate systems dedicated to
propulsion and ships' support system.
According to Office of Naval Research officials, the Integrated Power
System (IPS) is an improvement that will enable conventional systems to
produce electrical power for both the propulsion system and ship's
support system. Specifically, it will:
* Enable transformational weapons systems (future electromagnetic
guns);
* Improve survivability by allowing rapid reconfiguration of power:
* Reduce acoustic signature or detection by sonar, and
* Reduce life cycle costs, because fewer components and less
maintenance will be required.
Figure:
[See PDF for image]
[End of figure]
Source: United States Navy.
Likely Propulsion Systems for Near Term and Future Ship Construction:
Near Term Ships--Propulsion Systems:
T-AKE, a new underway replenishment vessel, utilizes a diesel-electric
propulsion system. Delivery of the first ship is in June 2006.
Littoral Combat Ship (LCS) is expected to have a hybrid propulsion
system of two gas turbines and two diesel engines. Delivery is expected
in FY 2007.
Future Ships-Propulsion Systems:
DDG 1000, a next generation destroyer, will have an Integrated Power
System consisting of four gas turbines and two advanced induction
motors. Delivery is expected in FY 2012,
LHA 6, an amphibious replacement ship, will utilize a combined gas
turbine and electric propulsion system. Delivery is expected in 2012,
VN 78, the first aircraft carrier to be built under the CVN 21 program,
will have a newly designed nuclear power plant, allowing for a
reduction in both manning and reactor plant components. Delivery is
expected in 2015.
CG(X), a next generation cruiser, likely to utilize an Integrated Power
System similar to that a DDG 1000.
Selected Technologies for Future Propulsion Systems:
The Office of Naval Research has identified same developing
technologies that will be applicable to future propulsion systems.
Research is heavily concentrated on improving electric drive propulsion
components for future ships.
The technology readiness level (TRL) indicates the maturity of a
technology. Levels range from TRL1, the lowest, to TRL9, the highest. A
TRL of 6 indicates that a technology is ready for consideration in an
acquisition program.
Table:
Technology: High Speed, high frequency generators;
Improvement: More power per unit weight, eliminates reduction gear;
Maturity Level: TRL-5-Integrated with other systems in the target
environment.
Technology: Direct thermal to electric conversion;
Improvement: Uses a heat source to produce electric power, ultimate
goal to eliminate steam and gas turbines;
Maturity Level: TRL 3-Proof-of-concept experiments to prove scientific
feasibility.
Technology: Wide bandgap power electronics;
Improvement: Improved efficiency and reduced size and weight;
Maturity Level: TRL 3-Proof-of-concept experiments to prove scientific
feasibility.
Technology: Superconducting motors;
Improvement: With the use of magnets, produces more force or torque in
a given size;
Maturity Level: TRL-3 (see above) or TRL-5 (see above) depending on
type.
Technology: Fuel cell technology;
Improvement: Fuel efficiency, modular nature which aids ship
survivability;
Maturity Level: TRL-4- Standalone experiments in a laboratory
environment or TRL-5 (see above).
Source: GAO analysis of United States Navy data.
[End of Table]
Navy Science and Technology Funding for Selected Propulsion
Technologies:
Propulsion Technology: High Speed Permanent Magnet and Superconducting
generators;
Total Amount Budgeted FY03-FY11: $16.5 M.
Propulsion Technology: Direct Energy Conversion;
Total Amount Budgeted FY03-FY11: $27.0 M.
Propulsion Technology: Wide Bandgap Power Electronics;
Total Amount Budgeted FY03-FY11: $18.1 M.
Propulsion Technology: Superconducting motors;
Total Amount Budgeted FY03-FY11: $132.5 M.
Propulsion Technology: Ship Service Fuel Cell and Related Technologies;
Total Amount Budgeted FY03-FY11: $46.4 M.
Propulsion Technology: Other Electric Ship Technologies;
Total Amount Budgeted FY03-FY11: $236.1 M.
Grand Total: $476.6 M
Source: GAO Analysis of United States Navy Data; 17.
[End of table]
(350779):
FOOTNOTES
[1] Pub. L. No. 109-163, § 130 (2006).
[2] Previously referred to as DD(X).
[3] Sea Power 21 is the Navy's vision of how it will organize,
integrate, and transform its forces to perform missions in the 21st
century. Its pillars are (1) Sea Strike, which is projecting precise
and persistent offensive power; (2) Sea Shield, which is projecting
global defensive assurance; and (3) Sea Basing, which is projecting
joint operational independence. Its ForceNet concept integrates the
three pillars.
[4] On June 14, 2006, the study had not been approved by senior Navy
officials.
[5] H.R. Conf. Rep. 109-360 (2005).
[6] Diesel fuel marine is a type of military fuel that is a complex
mixture of hydrocarbons produced by distillation of crude oil. The cost
of diesel fuel marine is approximately 15 percent greater than that of
crude oil.
[7] GAO, Navy Aircraft Carriers: Cost-Effectiveness of Conventionally
and Nuclear-Powered Carriers, GAO/NSIAD-98-1 (Washington, D.C.: Aug.
27, 1998).
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