Life cycle assessment of the solar thermal power plant integrated with air-cooled supercritical CO2 Brayton cycle

Abstract

Supercritical carbon dioxide (sCO2) Brayton cycle offers the potential of higher thermal efficiency and lower costs of electricity generation for concentrated solar power (CSP) applications. Besides its economic potential, the environmental sustainability needs to be examined. For this purpose, detailed life cycle assessment (LCA) of the solar driven sCO2 power generation system is carried out. The pollutant emissions and primary energy consumptions of the CSP plant with two typical sCO2 Brayton cycles including simple recuperative cycle and recompression cycle are analyzed and compared. Global warming potential (GWP), acidification potential (AP), respiratory effects potential (REP) are obtained. The life cycle greenhouse gas (GHG) emissions of parabolic trough (PT) plant with sCO2 cycle and steam Rankine cycle are compared. Finally, uncertainty analysis is carried out to study the effect of environmental factors (solar irradiation and ambient temperature) and parameter design of the PT system (turbine inlet temperature, life span and thermal energy storage (TES) capacity) on the LCA results and ensure the reliable comparison. It is found that for the PT plant with sCO2 power cycle, the auxiliary electricity consumption from the grid, TES and solar field manufacture account for 92% of the total environmental impact and 98% of the total energy consumption, while sCO2 power cycle only accounts for a small part. The environmental performance of the recompression layout is better than that of the simple recuperative layout. For the CSP application, the GHG emissions of the sCO2 cycle are 21%∼41% less than that of the steam Rankine cycle.