Coupled chemical-thermal solar power system and method

Abstract

A CSP system is disclosed which couples a thermal and a chemical energy pathway. The thermal pathway utilizes a heat transfer fluid to collect concentrated sunlight as thermal energy at medium temperature and transfer this energy to a thermal-to-electric power cycle. In parallel, the chemical pathway uses a redox material which undergoes direct photoreduction in the receiver to store the solar energy as chemical potential. This redox material is then oxidized at very high temperatures in the power cycle in series with the thermal pathway heat exchanger. This coupling allows the receiver to perform at the high efficiencies typical of state of the art thermal power towers while simultaneously achieving the power cycle efficiencies typical of natural gas combustion plants and achieving a very high overall solar-to-electric conversion efficiency.

Description

TECHNICAL FIELD[0001]The embodiments disclosed herein include systems and methods in the field of concentrating solar power (“CSP”) generation, also known as solar thermal power generation. The disclosed systems and methods generally utilize two coupled parallel energy pathways, one thermal and one chemical, to convert solar energy to electrical energy at high efficiency. Specifically, the disclosed embodiments include a solar receiver in communication with separate chemical energy storage material and heat transfer fluid flowing or transported in separate pathways. The chemical energy storage material undergoes low temperature photoreduction at the receiver. In addition, heat transfer fluid (“HTF”) is heated to an operational temperature at the solar receiver. The chemical energy storage material and HTF are used to drive a power cycle which operates at relatively high temperatures because the chemical energy storage material is exothermically oxidized as, or in sequence with, the ...

AI Technical Summary

Benefits of technology

The patent discloses a system and method for concentrating solar power (CSP) that combines a thermal and chemical energy pathway. The system uses a heat transfer fluid to collect and transfer sunlight to a power cycle, while a redox material is used to store the solar energy as chemical potential. The redox material is then oxidized at very high temperatures to release the energy in the power cycle. This coupling allows the receiver to function at high efficiency, similar to state-of-the-art thermal power towers, while also achieving the high efficiency of natural gas combustion plants. The system also includes an oxidizer that facilitates the chemical oxidation of the redox material and enhances the heat exchange between the redox material and the working fluid of the power cycle. This use of parallel energy pathways results in a highly efficient CSP plant.

Problems solved by technology

These types of towers typically operate at temperatures up to about 600° C. Greater power generation efficiency could be achieved with operational temperatures in excess of 600° C. It is difficult to achieve operational temperatures above 600° C. with conventional CSP strategies.

The foregoing chemical methods are not particularly well suited for the generation of electrical power using known power turbine based power cycles.

The thermal-to-electric conversion system is very similar to fossil fuel systems at comparable temperatures, however, the conversion efficiency of a solar power cycle is typically much less than that of a combined cycle gas plant due to the lower operational temperatures.

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