Optimization of solar thermal power plants

The energy demand expected increase and the even more impacting greenhouse effect promote many effort to increase the renewable contribute in several electric markets and is expected to increase further in the next years. The increasing penetration of PV and wind energy, that are for definition unpredictable and variables, in several markets is forcing the power plants (both fossil and renewable) to operate with a high level of flexibility and a high dispatchability is becoming a requirement as important as a low price. In spite of a higher LCOE, Concentrated Solar Power (CSP) plants are recognized as the favorite way to produce electricity thanks to the availability of an embedded long-term storage system that allows supplying thermal energy when the irradiation is low (or fluctuating) and can extend (or shift) the operation of the plant according to the power demand variability. This thesis proposes the assessment of the central receiver system (CRS), considered the best option over CSP technologies. Nevertheless, many aspects still penalize the tower systems, mainly the higher installation costs and the lower energy density. The optimal design of the heliostat layout and the selection of the optimal geometrical/design parameters (tower height and receiver dimensions, among all) are fundamental to improve the performance of CRS, independently of the operation mode of the plant (connected or not to the grid). Successively, the capacity of a solar tower system operating in island-mode to fulfill the power demand is investigated, compared with the most mature PTC technology. Finally, the integration of the CRS is investigated in a fully renewable production system (PV+Wind turbines+CSP) where 90% of the load must be satisfied.