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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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To order by Phone: Voice: (202) 512-6000 TDD: (202) 512-2537 Fax: (202) 
512-6061: 

To Report Fraud, Waste, and Abuse in Federal Programs: 

Contact: 

Web site: www.gao.gov/fraudnet/fraudnet.htm E-mail: fraudnet@gao.gov 
Automated answering system: (800) 424-5454 or (202) 512-7470: 

Congressional Relations: 

Gloria Jarmon, Managing Director, JarmonG@gao.gov (202) 512-4400 U.S. 
Government Accountability Office, 441 G Street NW, Room 7125 
Washington, D.C. 20548: 

Public Affairs: 

Paul Anderson, Managing Director, AndersonP1@gao.gov (202) 512-4800 
U.S. Government Accountability Office, 441 G Street NW, Room 7149 
Washington, D.C. 20548: