A techno-economic appraisal of parabolic trough collector and central tower receiver based solar thermal power plants in India: Effect of nominal capacity and hours of thermal energy storage

To increase the share of solar thermal power in the energy mix, deployment of large capacity plants with the provision of thermal energy storage can be an attractive option subject to their techno-economic feasibility. In this paper, an attempt has been made to assess the effect of the nominal capacity and the hours of thermal energy storage on the techno-economics of solar thermal power plants in India. Based on two commercially proven solar concentrating technologies (parabolic trough collector and central tower receiver) and two condenser cooling technologies (wet-cooled and dry-cooled), three solar thermal power plants i.e., wet-cooled parabolic trough collector, dry-cooled parabolic trough collector and dry-cooled central tower receiver have been considered in the study. For the analysis, four different nominal capacities (50 MW, 100 MW, 150 MW and 200 MW) for parabolic trough collector based plants and three nominal capacities (50 MW, 100 MW and 150 MW) for central tower receiver based plants along with seven different values of hours of thermal energy storage (0, 3, 6, 9, 12, 15 and 18 h) have been considered. The capital cost has been estimated based on inventory of materials based approach. The estimated values for the levelized cost of electricity are highest for dry-cooled parabolic trough collector based plants (higher by 26% and 33%, respectively than the estimated values for wet-cooled parabolic trough collector and dry-cooled central tower receiver based plants). Further, the economy of scale was also observed in estimating capital expenditure with an increase in nominal capacity and hours of thermal energy storage. From the viewpoint of the project developer, for the same capital expenditure, wet-cooled parabolic trough collector based plants (without thermal energy storage) of higher nominal capacities are observed to be techno-economically more viable as compared to relatively smaller nominal capacity plants with significant hours of thermal energy storage. On the contrary, for central tower receiver based plants, it is technoeconomically advantageous to increase hours of thermal energy storage in an existing lower nominal capacity plant compared to planning a higher nominal capacity central tower receiver based plant without storage.