Applications for Advanced Energy Conversion Applications

Abstract

Abstract Forest fires that endangered remote US Air Force sites equipped with radioisotope thermoelectric generators (RTGs) prompted the assessment of power generating systems that could be substituted for RTGs in small scale (10–120 watt) applications. Other non-RTG sites were also studied during the assessment. The power system assessment was conducted by the Air Force Research Laboratory (AFRL). The evaluations included engine-driven generators, solar, wind generators, propane thermoelectric generators (TEGs), batteries, fuel cells, and power systems based on advanced conversion technologies; such as, thermionics, free piston Stirling Engines (FPSE), alkali metal thermoelectric conversion (AMTEC), and thermophotovoltaics (TPV). The assessment team concluded that continued use of the RTGs is clearly the safest, most reliable, and most economical approach to supplying electrical power for remote, difficult to access locations. If political considerations force the replacement of the RTGs, the likely replacement is a hybrid system consisting of solar-PV with a propane-TEG for off-solar times. The transport of combustible fuels in Arctic environments is extremely expensive. It is this high logistics cost that signaled the need to consider the option of more efficient and cost effective power sources for the remote, Arctic applications. This paper summarizes AFRL contractual efforts involving two of the more attractive advanced conversion technologies: AMTEC and TPV. The information cited herein is the result of USAF sponsored programs and cooperative efforts with NASA Lewis Research Center (NASA-LeRC). This paper is not intended to reflect the progress and efforts of the energy conversion community as a whole.