This report provides background information on options for technologies that could reduce the Navy's dependence on oil for its ships. It is based on testimony prepared for a hearing on alternative Navy ship propulsion technologies held on April 6, 2006, before the Projection Forces Subcommittee of the House Armed Services Committee, which granted permission for the testimony to be converted into this report. The report discusses four general strategies for reducing the Navy's dependence on oil for its ships: reducing energy use on Navy ships; alternative hydrocarbon fuels; nuclear propulsion; and sail and solar power. Following this discussion is a section on legislative activity. A July 2006 Government Accountability Office (GAO) report discusses the status of Navy studies on alternative ship propulsion methods and certain Navy efforts for developing new ship-propulsion technologies. One strategy for reducing the Navy's dependence on oil would be to reduce energy use on Navy ships. The Department of Defense (DOD) testified in September 2006 that its energy use represents about 1.2% of total U.S. energy use, and that DOD in FY2005 consumed roughly 125 million barrels of oil. Of total DOD energy use, DOD testified, mobility fuels for aircraft, ships, and vehicles account for about 74%. Jet fuel, which is used not only by aircraft, but also by tanks, other ground vehicles, and electrical generators, accounts for 58% of DOD's consumption, DOD testified, while marine diesel fuel accounts for 13%. The Navy stated in October 2006 that it uses about 41 million barrels of oil per year for all purposes (about 33% of the above-mentioned DOD figure of 125 million barrels in FY2005), and that in FY2005, the Navy spent $900 million for fuel for its ships and aircraft, or about 32% of the DOD total of $2.83 billion for that year. For fossil-fueled Navy ships, reducing energy use can reduce fuel costs and increase cruising range. Increasing cruising range can improve operational flexibility by increasing the time between refuelings and the distance that the ship can operate away from its next refueling point. It might also reduce the ship's infrared signature, and thus increase its survivability, by reducing emissions of hot exhaust gasses. If applied to a significant number of ships, an increase in cruising range might permit a reduction in Navy costs for fuel-related force structure (e.g., oilers) and infrastructure (e.g., storage facilities). A 2001 report by a Defense Science Board (DSB) task force on improving the fuel efficiency of DOD weapon platforms stated: The Navy has had a program since 1977 to improve weapon platform fuel efficiency, focused primarily on legacy systems. The Navy staff estimates it has reduced the fuel consumption of the ship and aircraft fleet by 15 and 6 percent respectively. Deployment of the technologies and products has been primarily through no- and low-cost routes, such as the normal overhaul process or procedural changes. However, fuel efficiency has not been given a high priority in future system design. Fuel consumption enters design tradeoffs as one of many components of operating cost, and in most cases is one of the least important components because its benefits are so undervalued for reasons presented [elsewhere in the report]. As a result of this undervaluation and split incentives, new fuel saving technologies that promise increased performance and positive return on investment do not compete well for funding if the initial investment is high and the savings do not appear for several years.... A portion of the Navy's Development, Test and Evaluation (DT&E) program (Categories 6.4 and 6.5) is specifically dedicated to improving the fuel efficiency of ships, primarily legacy ships. This program began in the late 1970s, with funding peaking at about $35M in 1984. After fuel prices dropped in 1985 the program was funded at a more modest level, settling to around $8M per year through the 1990s. The DSB report listed options for power-plant improvements that could improve fuel efficiency by 3% to 8%, options for hull-system hydrodynamic improvements that could improve fuel efficiency by another 3% to 8%, and options for improvements to hull coatings and cleaning, auxiliary systems, sensors, controls, and procedures, and "hotel loads" (functions such as lighting and fresh water production) that could lead to further improvements in fuel efficiency. Some of the options listed in the DSB report are discussed in greater detail below. Dr. Amory Lovins, the director of the Rocky Mountain Institute (RMI) and a member of the DSB task force, estimated in 2001 that as much as 30% of the Navy's non-aviation fuel appears to be used to generate power for hotel loads. A study conducted by RMI for the Navy in 2001 of energy use on the Aegis cruiser Princeton (CG-59) found that hotel loads on these ships could be substantially reduced. According to the DSB report, the RMI study "found retrofittable hotel-load electric savings potential on the order of 20 to 50 percent, with significant further opportunities still to be assessed. Many of the savings opportunities were purely operational, requiring little or no investment." In an online article about the RMI study, Dr. Lovins stated: The Naval Sea Systems Command's [NAVSEA's] able engineers had estimated that 19 percent could be saved on ships of this class, of which Princeton was in the top one fourth for efficiency.... Our preliminary survey found gratifyingly large potential savings: perhaps, if found feasible, as much as several times NAVSEA's expectations. Princeton uses nearly $6 million worth of diesel-like turbine fuel each year. Her gas turbines, akin to those on an older passenger jet aircraft, use about $2-3 million worth of oil to make up to 2.5 megawatts of electricity, the rest for 80,000 horsepower of propulsion. The RMI team found that retrofitting motors, pumps, fans, chillers, lights, and potable water systems could save an estimated 20-50 percent of the ship's electricity. That could cut total fuel use by an estimated 10-25 percent.... Just as in civilian facilities ashore, the RMI team started by calculating what it's worth to save a kilowatt-hour. Since the electricity is being made inefficiently from fuel that's mainly delivered by "oiler" ships, the answer is an eye-popping 27 cents, six times a typical industrial tariff ashore. This high cost makes "negawatts" really juicy. For example, each percentage point of improved efficiency in a single 100-horsepower always-on motor is worth $1,000 a year. Each chiller could be improved to save its own capital cost's worth of electricity (about $120,000) every eight months. About $400,000 a year could be saved if—under noncritical, low-threat conditions—certain backup systems were set to come on automatically when needed rather than running all the time. Half that saving could come just from two 125-horsepower firepumps that currently pump seawater continuously aboard, around the ship, and back overboard. In a critical civilian facility like a refinery, where one wanted to be equally certain the firefighting water was always ready, one would instead pressurize the pipes (usually with freshwater) with a 2-hp pump, and rig the main pumps to spring into action the instant the pressure dropped. Princeton's total electricity-saving potential could probably cut her energy costs by nearly $1 million a year, or about $10 million in present value [over the ship's life cycle], while improving her warfighting capability. A bulbous bow ( Figure 1 ) can reduce a ship's wavemaking resistance and thereby increase its fuel efficiency. The Taylor Bow—an early form of the bulbous bow developed by U.S. naval architect and engineer David W. Taylor—was installed on the battleship Delaware (BB-28), which entered service in 1910, and subsequently on other large, higher-powered U.S.-built ships. The Inui Bow—a new form of the bulbous bow developed by Takao Inui of Japan in the late 1950s and early 1960s—is widely used on large commercial ships, where it typically reduces fuel consumption by about 5% at cruising speeds, and is now being applied to smaller commercial ships. Navy aircraft carriers, amphibious ships, and auxiliary ships and DOD sealift ships now feature bulbous bows, and the Navy has examined the idea of incorporating them into other ships, such as surface combatants. A study by the Navy's David Taylor Model Basin estimated that fitting a bow bulb onto an Arleigh Burke (DDG-51) class destroyer could reduce its fuel use by 3.9%, saving 2,400 barrels of fuel per year. An earlier (1994) study by the same organization estimated that 79 existing Navy cruisers and destroyers could be fitted with bow bulbs for a total development and installation cost of less than $30 million, and that the constant-dollar life-cycle fuel savings of the 79 ships would be $250 million. DOD stated in 2000 that fitting bulbous bows onto 50 DDG-51s (a total of 62 DDG-51s have been procured) could save $200 million in life-cycle fuel costs. The near-surface bow bulb designed for the DDG-51 ( Figure 2 ) accommodates the ship's existing bow sonar dome. A developer of the bow bulb stated that "Due to funding cut backs, the [DDG-51] bow bulb has not yet been transitioned to sea." A stern flap ( Figure 3 ) is a relatively small plate that extends behind a ship's transom, lengthening the bottom surface of the hull.