Exergy analysis and economic estimate of a novel solar and gas combined system

Abstract

In this paper, a novel parabolic-trough solar and gas combined (PSGC) system is proposed to explore a new potential utilization approach of solar energy. The working principle of this PSGC system is introduced. The operation behavior estimate and exergy analysis of the system are conducted. The results show that this PSGC system has an output power of 96.1 MW and an efficiency of 45.8%. The solar heat-to-electric efficiency is 21.6%. As the solar intensity augments, the output power as well as the proportion of the solar energy increases. The maximum exergy loss and minimum exergy efficiency both occur in the parabolic-trough-based solar direct steam system (SDSS), which are 30.5 MW and 30.75%. The exergy loss and exergy efficiency of the SDSS both increase as the solar intensity increases. With the solar intensity increased, for the steam turbine (ST), the exergy loss in the high-pressure ST decreases, the exergy loss in the low-pressure ST increases, and the exergy efficiency variations in the high- and low-pressure STs are both very small. The economic analysis results indicate that the PSGC plant is economically feasible and its net present value and internal rate of return are 447.94 million yuan and 19.5%, respectively.