Solar thermal power system concepts for high power satellites

Significant advances in the development of light-weight, compact, reliable, and cost-effective electrical power system (EPS) components are required to enable the design of future large satellite systems (10-100 kW_e). Alkali-metal thermal-to-electric converters (AMTEC), a form of direct energy conversion technology, are being developed as a high efficiency, radiation hard converter for high electrical power on a satellite platform. A satellite electrical power system based on AMTEC would consist of a collector to gather sunlight and focus the energy into a receiving cavity surrounded by AMTECs to convert the thermal energy to electrical energy. Large systems are robust and have been projected to achieve specific power levels as high as 14 W_e/kg in geosynchronous orbits and power levels as high as 150 kW_e. An AMTEC based system would accept thermal energy at 1200 K, reject heat at 600 K, and could achieve as high as 25% efficiency with 120 W_e/kg and 200 W_e/1 (AMTEC component level) at high voltage (100 V). This paper outlines a conceptual high power solar-thermal system utilizing AMTEC and examines the advantages and disadvantages of such as system as compared to conventional photovoltaic based systems