Synthesis of an Electrical Power System for a Manned Lunar Base

Current program planning in the area of lunar surface explorationenvisions missions of increasing energy requirements and duration.During the mid 1970´s it has been estimated that the electrical powerrequirements for a 3-man mission of one year duration might be in theorder of 33 000 kWh. Load profiles to support regeneration of fuelcell reactants for lunar roving vehicles and base nighttime operationsindicate potential power levels of from 30 to 100 kW. An electricalpower system using a state-of-the-art photovoltaic energy conversionsource was postulated on the assumption that nuclear power systemtechnology would not be flight ready by this time period.The process of synthesizing an overall electrical power system isdiscussed. Included are analyses and system design rationale. A rangefrom 50 to 500 volts dc is considered and the effect on weight andefficiency determined. Additional system criteria such as thermalcontrol, reliability, and emergency operation are discussed. A shred-out oftotal system weight as a function of voltage and regulation is presentedfor a 36 kWload. The impact ofload level, conditioning efficiency,transmission length, and temperature on system weight is discussed. Sensitivityivity curves depicting the effect of variations in these parameters areprovided.It is concluded that an efficiency of 80 percent or greater can beattained by matching the load profile with distribution voltage.