Numerical simulation of a 50 MWe parabolic trough power plant integrating a thermocline storage tank

A simulation of a 50 MWe power plant with thermocline tank as storage shows that there is no deterioration of the thermocline performance with cycling (successive charges and discharges), because no temperature threshold has to be taken into account during charges. Indeed, the best control strategy when the thermocline outlet fluid temperature increases during charge is defocusing a part of the solar field to avoid the heat transfer fluid overheating. Thus, thermocline tank can be fully charged during summer days. During winter days, if there is not enough energy to perform a full charge, cycling effect does not occur because the remaining energy after partial discharge implies a more important state of charge for the following day. Finally, the comparison between thermocline and two-tank technologies shows that oversizing the thermocline tank by 11% leads to equivalent electricity production, for a lower cost (at least 22.3%).