Abstract
Solar energy has the potential to provide most of the electricity needed by mankind sustainably into the indefinite future. Concentrated Solar Power (CSP) has conventionally been considered more applicable than photovoltaic (PV) for baseload power since thermal storage is far cheaper than battery storage. However, the solar fields for CSP are relatively expensive. On the other hand, PV plants without storage deliver electric power at a much lower cost than CSP plants of comparable capacity without storage. Integrating both technologies is an attractive approach towards solar baseload power with affordable levelized cost of energy (LCOE). This study, which investigates the two cities of Saudi Arabia, consists of simulation and optimization in three main parts: The first part is a simulation of the CSP parabolic trough (CSP-PT) standalone plant and integrating the output parameters with an economic model to calculate the LCOE. The second part is the simulation of combined CSP-PT with PV, with a design strategy of utilizing all PV power for daytime use, and supplementing the PV output with thermal power as needed to maintain baseload operation in the daytime. The third part is the simulation of combined CSP-PT with a design strategy of providing all or nearly all daytime power with PV, with the utilization of excess energy from PV to supply heat to the thermal storage system. The results show that for a target capacity factor of 79%, the CSP plant alone requires a solar multiple of 6 in Riyadh and 3.5 in Tabuk. For both locations, the introduction of the hybrid concept substantially reduced the solar multiple. In Riyadh, the solar multiple ranged from 2.9 to 3 with the PV portion of the plant having a nameplate capacity equal to that of the CSP portion and 1.95 for a case with the PV nameplate capacity 60% greater than the CSP portion. For these same cases in Tabuk, the solar multiples were 1.78–1.85 and 1.6 simultaneously. Generally, hybridization is of greater benefit in Riyadh than in Tabuk owing to the greater fraction of solar resource in the form of diffuse sunlight which can be collected by the PV plant but not by the CSP plant. The LCOE was reduced by hybridization in both locations, but again the benefit was greater for Riyadh. Clearly, from a technological perspective, it is important to study the hybridization for an individual city based on its weather data as the incorporation of PV into CSP plant designs should be considered for all locations in order to reduce the cost to provide baseload power from solar energy, and the application of the hybridization concept can extend the applicability of CSP technology to regions with less direct sunlight than would be economically feasible with CSP alone.