Exergy and thermo-economic analyses and performance comparison of different solar aided coal-fired power systems

Abstract

A solar aided coal-fired power (SACP) system has proven to be an efficient method to use solar energy on a large scale and reduce fossil fuel consumption in coal-fired power systems. In this study, three different SACP systems were investigated using thermo-economic analysis method to evaluate the systems’ production performance in detail. Moreover, sensitivity analysis was performed to explore the influences of the coal price and solar field investment. The exergy analysis shows that, for all these systems, the boiler and solar field have the largest and second-largest exergy destruction, respectively. The exergy cost and thermo-economic cost analyses show that the SACP system, where the solar field is placed between intermediate- and low-pressure turbines, has the best system performance. The unit exergy cost and the unit thermo-economic cost of the electricity of this system are 2.60 kW/kW and 7.96 US$/GJ, respectively. Furthermore, the standard coal consumption rate of this system is 275.16 g/kWh. The sensitivity analysis shows that with continuing solar field cost reductions, the unit thermo-economic cost of the electricity will further decrease in the future.