Capability of a small size CSP plant to provide dispatch power

In Concentrating Solar Power (CSP) plants, large amounts of energy collected by the solar field can be stored and converted to electricity when required, with a time-shift of several hours between thermal energy collection and electricity production. The present work investigates the capabilities of a CSP plant to produce electricity with scheduled power output curves, having different power levels, starting hours and time durations. In particular, the analysis was carried out with reference to the 600 kWe CSP section of the pilot hybrid solar power plant under construction in Ottana (Sardinia-Italy), which use linear Fresnel collectors, thermal oil as heat transfer fluid, a two-tank direct energy storage system and a ORC power generation unit. The study has been carried out for the four seasons of a reference year by using a second-based simulation model. The results show that the dispatch capabilities of the CSP plant are of great interest especially during spring and summer, even with reference to output profiles with high power levels and long-time durations. On the contrary, during autumn and winter the power output and the time duration has to be significantly reduced in order to achieve acceptable dispatch capabilities. Moreover, the study demonstrates that the storage thermal losses do not significantly reduce the dispatch capabilities of the CSP to produce the same power curve with a time shift of few hours.