Feasibility analysis of megawatt scale solar thermal power plants

Abstract

In this article, feasibility analysis of solar thermal power plants is carried out for large scale power generation. Three different configurations of concentrating solar power technologies such as linear Fresnel reflector collector (LFRC), parabolic trough collector (PTC), and power tower (PT) are analyzed for power generation in stand-alone mode and various plant capacities such as 1 MWe, 5 MWe, 10 MWe, 30 MWe, and 50 MWe. The maximum achievable steam conditions in LFRC system has been considered for all the power plant capacities as 55 bar and 270 °C. In case of parabolic trough and power tower, the steam parameters have been considered as 60 bar, 370 °C for 1 MWe, 65 bar, 400 °C for 5 MWe, 65 bar, 410 °C for 10 MWe, 100 bar, 410 °C for 30 MWe, and 100 bar, 410 °C for 50 MWe. The feasibility of stand-alone solar power plants (SASPPs) is compared with coal fired power plant (CFPP) and solar aided coal fired power plant (SACFPP). The feasibility analysis in terms of performance and levelised electricity cost (LEC) is carried out for various technologies with capacities. It is observed that the LFRC power plants are relatively less efficient than others due to lower optical and thermal efficiency. The energy and exergy efficiencies of a 50 MWe LFRC power plant are found as 12.17% and 17.21%, respectively. The efficiency of 50 MWe solar PTC power plants is found as 23.16% which is higher than other technologies. The net exergy efficiency of PTC power plants increases from 23.14% to 32.76% for the plant capacity increases from 1 MWe to 50 MWe. It is observed that the exergy efficiency decreases from 22.57% to 19.65% as plant capacity increases from 1 MWe to 10 MWe due to shading and blocking for PT power plants and then increases to maximum of 23.33% for the 50 MWe power plant. The exergy efficiencies of 50 MWe CFPP and SACFPP have been estimated as 28.17% and 28.21%, respectively. The environmental benefits of stand-alone solar power plants are estimated in terms of CO2 mitigations and compared with CFPP. The LEC of CFPP, SACFPP, and SASPP is found as INR 3.56/kWh, INR 3.60/kWh, and INR 8.48/kWh, respectively. The discounted payback period, benefit-to-cost ratio, and net present value of all the power plants are also estimated.