Quantum and Thermal Conversion of Solar Energy to Useful Work

This paper will summarize the results of a thermodynamic analysis of quantum; and thermal processes for converting sunlight into useful work. Quantum and; thermal processes acting alone as well as combined quantum-thermal processes will be discussed. Two types of combined processes have been analyzed, the thermally coupled process and the thermally decoupled process. These processes wereaddressed because there is a hope that a combined quantum-thermal conversion system will prove to be cheaper than either system acting separately. A first step in determining cost is to determine maximum system efficiency. The analysis also indicates the concept with the greatest potential so that further efforts can focus on it. Previous analyses of the thermodynamics of quantum and thermalconversion have been performed by Haught (Ref. 1), Bolton (Ref. 2), Ross (Ref. 3) , and others. This paper will review Haught's analysis and present the results of an extension of this analysis to a thermally decoupled combined quantum/thermal system performed at SERI. Only systems using unconcentrated solar flux will be considered in the present analysis.