(fossil) fuels with internal combustion engines and steam or gas turbines. The 

 specific selection of fuels and conversion system will depend on such factors 

 as power level, efficiency, fuel logistics, system availability, and operating 

 cost. 



The liquid and gaseous fluid were considered the best suited for power 

 levels of 30 to 3,000 kw because they require a minimum of handling or 

 processing equipment. Fuel oils are generally the most readily available at 

 the lowest cost. Further, the fluid fuels may be used with all conversion 

 systems and will not influence the selection of any one conversion system. 



The diesel engine was preferred to the steam or gas turbine as a prime 

 mover for practically all the criteria established for the study program. Spark 

 ignition engines were not considered because of their low efficiency and the 

 requirement for highly volatile fuels. The diesel-driven generator system is 

 approximately twice as efficient as the steam or gas turbine for the power 

 range of 30 to 3,000 kw, with overall efficiencies of 17% at 30 kw, 27% at 

 100 kw and 30% from 300 to 3,000 kw. Increased efficiency results in sub- 

 stantially lower fuel cost and has a large effect on logistics support. The 

 diesel engine also has a lower acquisition cost and is readily available in a wide 

 range of capacities to match system requirements. 



Steam and gas turbines are generally restricted to higher power levels 

 because of poor performance and because of their limited availability at the 

 low power level?. The gas turbine weighs less than the diesel engine, but this 

 advantage is quickly offset by the increased weight of fuel that must be pro- 

 vided for the gas turbine. The steam plant is generally larger and heavier and, 

 for the power levels of interest, less efficient than the diesel system. Reactor 

 power sources were not specifically considered for applications other than the 

 in-situ power plants since they are not economically competitive with fossil- 

 fueled systems at the power levels of interest. 



The diesel engine may be employed as the shore-based or ocean surface 

 power plant for the 30 kw to 3,000 kw power levels. Table 6 presents typical 

 data for diesel engine generator sets over the range of interest for the surface 

 power systems, with transmission losses limited to approximately 5%. Shore- 

 based systems with long transmission lines will require correspondingly larger 

 power plants. 



A single engine generator set results in a minimum of complexity 

 in instrumentation and control and is the most economical installation. 

 However, reliability of the load module may require redundant equipment. 

 Life expectancy of a diesel generator is estimated at 20 years, with programmed 

 preventive maintenance. For ocean surface power plants the major maintenance 

 cycles can be scheduled to coincide with hull or buoy maintenance. 



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