The impact of concrete structure on the thermal performance of the dual-media thermocline thermal energy storage (TES) tank which is very promising to be applied in concentrating solar power (CSP) systems is investigated. The lumped capacitance method is used since the introduction of corrected heat transfer coefficients between solid and fluid extends the validity of this method to large Biot numbers. The discharging performance of four typical concrete structures including the channel-embedded structure, the parallel-plate structure, the rod-buddle structure and the packed-bed structure is studied. The thermocline behaviors during the discharging process for the four structures with the influences of feature size and fluid inlet velocity are analyzed, and the corresponding effective discharging efficiency and discharging time are reported. The results show that the concrete TES tanks with four different structures show different thermocline behaviors during the discharging process. The packed-bed structure gives the best discharging performance, followed by the rod-bundle structure, the parallel-plate structure and the channel-embedded structure sequentially. The discharging performance is also found to be influenced to some extent by the feature size and the fluid inlet velocity for all four different structures. (C) 2013 Elsevier Ltd. All rights reserved.